PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Punjab State Board PSEB 8th Class Social Science Book Solutions History Chapter 9 When, Where and How Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Social Science History Chapter 9 When, Where and How

SST Guide for Class 8 PSEB When, Where and How Textbook Questions and Answers

I. Write down the answer of the following questions:

Question 1.
In which three periods the Historians have divided the Indian History?
Answer:
Historians have divided the Indian History in three periods and these are:
(a) Ancient period
(b) Medieval period
(c) Modern period.

Question 2.
When modern period started in India?
Answer:
It has been considered that modern period, in India, was started in 18th century after the death of Aurangzeb.

Question 3.
When independent state of Hyderabad was founded and who founded it?
Answer:
Independent state of Hyderabad was founded by Nizam-ul-Mulk in 1724 A.D.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 4.
Write down the names of the European powers who came to India during the modern period.
Answer:
Portuguese, Dutch, French and the British.

Question 5.
When and by whom the independent state of Avadh was founded?
Answer:
Avadh was declared as an independent state by Saadat Khan in 1739 A.D.

Question 6.
How books as historical sources help us?
Answer:
A number of books were printed in modern age in English and in Indian languages due to the invention of printing press. With these books, we come to know about human development in different fields such as literature, art, history, science and music. These books are very helpful in increasing our knowledge about history and science. We can take inspiration from these books to do progress in our lives.

Question 7.
Write down in brief about the historical buildings.
Answer:
Historical monuments, built in the modern age, are the living examples of History. A number of historical monuments still exist is our country and still are in very good condition. India Gate, Parliament House, President House, Birla House and other buildings are included in it. These monuments tell us about different aspects of Indian art and architecture.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 8.
How Newspapers, Magazines and Pamphlets are helpful in writing history?
Answer:
A number of newspapers, magazines and pamphlets, in different Indian languages, were printed in modern age in India. Out of them ‘The Tribune’, ‘The Times of India’ and many other newspapers are still printing. Ah these newspapers and magazines give us information of many important events of modern age. Even they print any particular news of that age in today’s newspaper. In this way they are helpful in writing history.

Question 9.
Write a note on Govt. Documents.
Answer:
Government documents are a very important source of history of modern India. We can get information about activities of foreign powers, the British conquest of India and the British administration in India through these documents. These documents also tell us that how India was economically exploited by the British. In other words Government documents are one of the important sources of writing history of modern India.

II. Fill in the Blanks:

Question 1.
In Europe Modern Period began in the __________ century.
Answer:
16th

Question 2.
There was __________ period in India in the 16th century.
Answer:
medieval

Question 3.
__________, __________, __________ Pathans and Rajputs etc. new powers emerged in the 18th century.
Answer:
Marathas, Sikhs, Rohillas

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 4.
In 1724 A.D., Nizam-Ul-Mulk founded an independent state of __________
Answer:
Hyderabad

Question 5.
In 1739 A.D., Sadaat Khan made an independent state.
Answer:
Avadh

Question 6.
Three carnatic curves were fought between the and Britishers during the period 1744 to 1763 A.D. which British got victorious?
Answer:
French

Question 7.
__________, newspapers, magazines, pamphlets and historical buildings are main sources of Modern Indian History.
Answer:
Books, government documents.

III. Write True or ‘False’ in the brackets given after each statement:

Question 1.
There were many social evils prevalent in India in the 18th century.
Answer:
True

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 2.
Western ideas enlightened the Indians along with western education and literature.
Answer:
True

Question 3.
In India Mughal Empire was more powerful in the 18th century.
Answer:
False

IV. Something To Do:

Question 1.
Write main sources of Modern Indian history on a chart with a picture of each source and paste it on the wall of your class room.
Answer:
Do it yourself with the help of your teacher.

PSEB 8th Class Social Science Guide When, Where and How Important Questions and Answers

Multiple Choice Questions:

Question 1.
Which of these is a part of periodization of Indian history?
(a) Ancient age
(b) Modern age
(c) Medieval age
(d) All of these.
Answer:
(d) All of these.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 2.
Which of these European powers came to India in modern age?
(a) British
(b) Dutch
(c) French
(d) All of these.
Answer:
(d) All of these.

Question 3.
Who among the following was the first Governor-General of India?
(a) Lord Dalhousie
(b) Warren Hastings
(c) Lord Wellesley
(d) Lord Canning.
Answer:
(b) Warren Hastings.

Question 4.
Which of these is a source of history of modern India?
(a) Books
(b) Historical Monuments
(c) Official Documents
(d) All of these.
Answer:
(d) All of these.

Question 5.
Who founded the independent state of Awadh?
(a) Nizam-ul-mulk
(b) Ali Vardi Khan
(c) Tipu Sultan
(d) Murshid Quli Khan.
Answer:
(a) Nizam-ul-mulk.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 6.
Identify the following pictures and tell with which period do these buildings belong?
PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How 1
(a) Ancient period
(b) Gupta Period
(c) Medieval period
(d) Modern period.
Answer:
(d) Modern period.

Question 7.
__________ Carnatic wars were fought between the French and the British.
(a) Two
(b) Three
(c) Four
(d) Five.
Answer:
(c) Four.

Question 8.
__________ period began in the 16th century in Europe.
(a) Medieval
(b) Modern
(c) Gupta
(d) Ancient.
Answer:
(b) Modern.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 9.
The given picture is of one of the famous historical building in India. Name the building.
PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How 2
(a) India Gate
(b) Qutub Minar
(c) President House
(d) None of these.
Answer:
(a) India Gate.

Question 10.
With which age the buildings given below are associated?
PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How 3
(a) Modern age
(b) Ancient age
(c) Medieval age
(d) None of these.
Answer:
(a) Modern age.

Question 11.
Identify the building in the picture.
PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How 4
(a) India Gate
(b) Qutub Minar
(e) President House
(d) None of these.
Answer:
(a) India Gate.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 12.
Which building of the following buildings is not situated in Delhi, the Capital of the country?
PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How 5
Answer:
(d) Taj Mahal

Fill in the Blanks:

Question 1.
Modern age in Europe started in __________ century.
Answer:
16th

Question 2.
There was __________ age in 16th century India.
Answer:
medieval

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 3.
In 18th century India, many new regional powers puch as____________, __________, __________ Pathan and Rajputs.
Answer:
Marathas, Sikhs, Rohillas.

Tick the Right (✓) or Wrong (✗) Answer:

Question 1.
Many social evils prevailed in Indian society during 18th century.
Answer:
(✓)

Question 2.
Western education and literature along with western ideas motivated Indians against the British.
Answer:
(✓)

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 3.
Mughal empire was quite powerful during 18th century.
Answer:
(✗).

Match the Following:

Question 1.

A B
1. Saadat Khan (i) Europeans
2. Nizam-ul-Mulk (ii) Avadh
3. Babur (iii) Hyderabad
4. Dutch (iv) Mughals

Answer:

A B
1. Saadat Khan (ii) Avadh
2. Nizam-ul-Mulk (iii) Hyderabad
3. Babur (iv) Mughals
4. Dutch (i) Europeans

Very Short Answer Type Questions

Question 1.
In how many periods, history of the world has been divided?
Answer:
World history has been divided in three periods and these are ancient period, medieval period and modern period.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 2.
In which century, medieval period was started in Europe?
Answer:
In 16th century.

Question 3.
Name any four new powers which emerged on political scene of India in the 18th century.
Answer:
Marathas, Sikhs, Ruhelas and Pathans.

Question 4.
When India became Independent?
Answer:
In 1947 A.D.

Question 5.
Why modern period in Europe started earlier than India?
Answer:
Modern period started very early in Europe, as compared to other countries, which developed very quickly. European countries also progressed very quickly.

Question 6.
Which step was taken by the Indian rulers of modern period to strengthen Indian economy?
Answer:
They gave encouragement to agriculture, trade and industries.

Question 7.
When and between whom were Carnatic wars fought? Who emerged victorious out of these wars?
Answer:
Carnatic wars were fought between the British and the French during the period of 1746-1763 A.D. The British emerged victorious out of these wars.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 8.
On what history is based and how historians reconstruct history?
Answer:
History is based on facts and historians use many sources to reconstruct history.These sources include books, government documents, newspapers, magazines, historical buildings, paintings etc.

Question 9.
Who founded Mysore State and under whom it progressed?
Answer:
Hyder Ali founded Mysore State and it progressed under the son of Hyder Ali, Tipu Sultan.

Short Answer Type Questions

Question 1.
How western education and literature in modern India paved way for Indian independence?
Answer:
A number of schools and colleges were established in the modern period in India where education was given in Indian languages as well as in English language. Western ideas also spread in country through western education and literature. Sense of liberty, equality and fraternity developed among such Indians who received education of philosophy, history and western civilization. They were not able to tolerate the British rule in India and were unable to tolerate the economic exploitation of the country. That’s why they started national movement against the British rule. They gave great sacrifices and suffered a lot and brought freedom for the country in 1947 A.D.

Question 2.
Write a note on the advent of independent states in India in modern period.
Answer:
Many provinces of the Mughal empire took advantage of its weakness and declared themselves independent. First of all Nizam-ul-Mulk founded Hyderabad state in 1724 A.D. After this, Murshid Quli Khan and Alivardi Khan made Bengal a free state. Saadat Khan founded the Avadh state in 1739 A.D. In the same way Hyder Ali founded the state of Mysore in the south. State of Mysore developed to a great deal under Hyder Ah and his son Tipu Sultan. The Marathas also took advantage of this situation. They started to attack Mughal provinces under the leadership of Peshwas.

Long Answer Type Questions

Question 1.
Explain the important sources of history of modern India.
Answer:
History depends upon facts. That’s why historians are dependent upon different sources for the creation of history. A number of sources are there to get information of history of modern India.

Some of these main sources are given below:
1. Books. A number of books were printed in the modern period in English language and in Indian languages due to the invention of printing press. With these books, we came to know about human development in different fields such as literature, art, history, science and music. We can take inspiration from these books to do progress in our lives.

2. Historical Monuments. Historical monuments, built in modern age, are the living examples of history. A number of historical monuments still exist in our country and still are in very good condition. India Gate, Parliament House, President House, Birla House and other buildings are included in it. These monuments tell us about different aspects of art and architecture of India.

3. Newspapers and Magazines. A number of newspapers, magazines and novels, in different Indian languages, were printed in modern age in India. Out of them ‘The Tribune’, “The Times of India’ and many other newpapers are still printing. All these newspapers and magazines give us information of many important events of modern age.

4. Government Documents. Government documents are very important source of the history of modern India. We can get information about the activities of foreign powers, the British conquest of India and the British administration in India through these documents. These documents also tell us that how India was exploited economically by the British.

5. Art and Sculptures. A number of pictures and sculptures are also there which are important sources of modern history. These sources give us information of important historical persons and national leaders.

6. Other Sources. Except given sources, some other important sources of modern Indian history are also there. Most important source out of these sources are films which throw some light on the life and lifestyle of contemporary people. Except this, we can come to know about personality and views of Gandhiji and Pt. Nehru from their own hand written letters and correspondence.

PSEB 8th Class Social Science Solutions Chapter 9 When, Where and How

Question 2.
Write down in detail over “An overview of the modern Indian history.”
Answer:
Modern age in India started in 18th century after the death of Aurangzeb. Some of the features can be seen from the different events of this age and these are given below:
1. Advent of New Powers. Many of the old powers weakened during this age and they were replaced by the new powers. Marathas, Sikhs, Ruhelas, Pathans and Rajputs were emerged as new powers.

2. Arrival of Foreign Powers. Mutual conflict of these Indian powers motivated foreign powers to establish their authority and supremacy in India. Portuguese, the British, Dutch and the French were included among these powers. Modern period in India started with the arrival of European powers.

3. Social and Economic Reforms. A number of social evils were there in Indian society as compared to foreign societies of this time. Many social reformers tried to remove these social evils from society. A number of defects were also there in the economic sector of country. That’s why Indian rulers, i.e. the British, gave special attention to agriculture, trade and industries. They also tried to remove such defects of economy from Indian society.

4. Beginning of National Movement and Independence of country. A sense of liberty, equality and fraternity aroused among those enlightened Indians who got education of history, philosophy and western civilization. They were not able to tolerate the British rule in India and were unable to tolerate economic exploitation of the country. That’s why they started national movement against the British rule. They gave many sacrifices and suffered a lot and brought freedom for the country in 1947 A.D.

5. Reorganization of Economy. Work of reorganization of the economy of country started after the achievement of independence. That’s why just within 69 years of freedom, Indian economy has been emerged as one of the fastest growing economy of the world.

Question 3.
Explain the main developments during modern period of Indian history.
Answer:
The age of 18th century or the beginning of modern age of Indian history is known as the Black age. It was so because country was weakened due to the decline of Mughal Empire. Conflict between local powers and foreign powers started in the country.

The advent of Independent States. Many small states or different provinces of the Mughal Empire took advantage of its weakness and declared themselves independent.

  • First of all, Nizam-ul-Mulk founded the independent state of Hyderabad in 1-724 A.D.
  • After this, Bengal was made an independent state by Murshid Quli Khan and Alivardi Khan.
  • Saadat Khan made an independent state of Avadh in 1739 A.D.
  • In the same way, Mysore state was founded in the South under the leadership of Hyder Ah.
  • The state of Mysore was greatly developed under the leadership of Hyder Ali and his son Tipu Sultan.
  • Marathas also took advantage of this situation and started invading Mughal states under the leadership of Peshwas.

Struggle among the Foreign Powers. European powers such as the Portuguese, Dutch, French, and British also took advantage of the weakness of Mughals and tried to establish their rule in the country. Three Carnatic wars were fought between the British and the French during 1746-1763 A.D. The British emerged victorious which paved the way for the establishment of British rule in India.

The British control over the Indian Economy. The Indian economy was severely damaged by the chaos which prevailed in the Indian politics of that time. The British took control of Indian trade. Handicraft work and artisan work both were destroyed by the British policies.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Punjab State Board PSEB 8th Class Social Science Book Solutions History Chapter 23 India after Independence Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Social Science History Chapter 23 India after Independence

SST Guide for Class 8 PSEB India after Independence Textbook Questions and Answers

I. Answer the following questions :

Question 1.
When Constituent Assembly was constituted and how many members it has?
Answer:
The Constituent Assembly was constituted in 1946 A.D. It has 389 members.

Question 2.
When the Constitution of India was passed and implemented?
Answer:
The Indian Constitution was passed on 26th November 1949 A.D. and implemented on 26th January 1950.

Question 3.
Who is given the credit for the unification of the Indian princely states?
Answer:
Sardar Vallabh Bhai Patel was instrumental in the unification of Princely States.

Question 4.
How Hyderabad state was merged with India?
Answer:
The state of Hyderabad was included in India with the help of the police. Indian police were sent over there on 13th September 1948 A.D. and this state was merged in Indian Union on 17th September 1948 A.D.

Question 5.
How Junagarh state was merged with India?
Answer:
Nawab of the Junagarh state wanted to be included in Pakistan. But Plebiscite (Public survey) took place over there on 20th February 1948 A.D. in which people wished to be included in Indian Union. That’s why Junagarh state was included in Indian Union.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 6.
How many members were in the state reorganization commission?
Answer:
This commission had three members.

Question 7.
Write down any two principles of Panchsheel.
Answer:

  1. Peaceful Co-existence
  2. Not to attack each other.

Question 8.
Where and when the first conference of Non-alignment was held?
Answer:
First conference of Non-Aligned movement was held at Belgrade in 1961 A.D.

Question 9.
Write down a note on Non-Aligned Movement.
Answer:
After the Second World War, the entire world was divided into two opposite alliances. America was the leader of one alliance which was known as Western Bloc. U.S.S.R. was the leader of second alliance which was known as Eastern Bloc. Serious Cold War started between them. Military treaties and pacts like Nato and Warsah Pact have made situation more tense. India wanted to keep its own sovereignty and didn’t become the member of any group. That’s why India started Non-Aligned Movement with the help of other countries. Founders of this movement were Pt. Jawahar Lai Nehru, Tito of Ugoslavia and Nasir of Egypt.

Non-Aligned Movement started in 1961 A.D. It was based on principles of Panchsheel. All the members of this movement didn’t want to include themselves in any of the alliance. Its first conference held at Belgrade in 1961 A.D. It was started with 25 members but now it has more than 100 members.

Question 10.
Write down a note on the foreign policy.
Answer:
India, after independence, adopted the foreign policy based on the concept of peaceful co-existence. Its main features are given below:

  1. India respects the sovereignty and freedom of all the countries of the world.
  2. India believed that people of all the religions, nations and races are equal.
  3. India strongly oppose those countries which discriminate the people on the basis of colour, race or class. For example, India had opposed the racial policy of South African Government and its discriminational policy with Asian people and original inhabitants of Africa.
  4. India believes that all international disputes should be resolved through peaceful methods.

Question 11.
Write down a note on Communalism.
Answer:
India is a secular country. People of different religions live over in India whose religious beliefs are different. Communal riots broke out in country at many occasions due to religious fundamentalism. Incident occurred at Gujarat in 2002 A.D. was one of the serious incident of such type. Many people are of the view that government should give special care to the interests of minorities.

Question 12.
Explain in brief the relation between India and Pakistan.
Answer:
India likes to keep friendly relations with all the countries, especially our neighbouring countries. Pakistan and China are the most important neighbouring countries of India.

Brief description of India’s relations with them is given below :
India and Pakistan. India has always tried to keep friendly relations with Pakistan. Pakistan didn’t give its sanction to Kashmir’s inclusion with India. That’s why Kashmir became the main reason of conflict between India and Pakistan. India and Pakistan have fought three wars with each other due to Kashmir problem. Kargil war of 1999 A.D. was one of them.

After the Indo-Pak war of 1971 A.D. Shimla Agreement was signed between Indian Prime Minister Indira Gandhi and Pakistani Prime Minister, Zulfikar Ali Bhutto. The main objective of this agreement was to peacefully resolve all the problems of Indo-Pak. That’s why Lahore Agreement was also signed between Indian Prime Minister Atal Behari Vajpai and Pakistani Prime Minister Nawaz Sharif. Bus service and Railway service was also started between both the countries. People of both the countries came closer to each other due to these services. Indian and Pakistani writers and social servers are free to move from one country to another. So the railway and bus services started between both the countries which could give strength to these friendly relations. We believe that the areas of disputes would be resolved in near future.

India and China. Indian relations with China remained friendly right from ancient times. Both countries were associated with each other due to trade and Buddhism. When Communist revolution came in China in 1949 A.D. then India was the first country to give sanction to new government of China. India also supported China as a member of U.N.O. An agreement took place between India and China in 1954 A.D. on the basis of Panchsheel. But both countries also fought war with each other due to border disputes. Very tense relations remained between both the countries for several years. These relations improved after 1980 A.D. Indian and Chinese Prime Ministers met each other on several occasions and discussed their areas of dispute. Today, both the countries are busy in solving their border disputes.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 13.
Write down details of the unification of the princely states.
Answer:
India had to face many problems after getting independence. One of these problems was of local kingdoms. They were 562 jp number and were ruled by Indian kings or rulers. According to Act of 1947 A.D., these kingdoms were free to keep their own freedom or were free to be included in the countries of either India or Pakistan. That’s why many local kingdoms liked to remain free. But first Home Minister of free India Sardar Vallabh Bhai Patel handled the matter with great intelligence and asked the rulers of local kingdoms to become a part of Indian union. Small kingdoms were included into provinces.

Some kingdoms were sharing cultural values and even they were sharing common boundries. They were joined and made state. For example kingdoms of Kathiawar were included in Saurashtra and the kingdoms of Patiala, Nabha, Faridkot, Jind and Malerkotla were joined to make Pepsu state. Now only three kingdoms remained which were not ready to be included in India and these were Hyderabad, Junagarh and Kashmir.

Hyderabad: Nizam of the kingdom of Hyderabad Usman Ah Khan refused to merge his kingdom into union of India. So Indian police was sent to Hyderabad on 13th September 1948 A.D. and on 17th September 1948 A.D. kingdom of Hyderabad was merged into union of India.

Junagarh. Nawab of Junagarh wanted to go with Pakistan. But plebiscite (Public Survey) took place in Junagarh on 20th February 1948 A.D. and public wished to be merged in Union of India. Therefore Junagarh was merged into union of India.

Kashmir. Ruler of Kashmir Maharaja Hari Singh also wanted to remain free. But Pakistan wanted to control kingdom of kashmir. So ruler of Kashmir called for Indian help and proposed to merge his state into Indian Union. Indian government accepted the request of ruler of Kashmir and send its army to Kashmir. War started between India and Pakistan but a large part of Kashmir was occupied by Pakistan.

Other Kingdoms. Except these kingdoms, there were certain other small kingdoms which were included in the nearby states. Baroda was included in the province of Bombay. Unified state was founded by joining few small states. For example one union was made in March, 1948 by joining Bharatpur, Dholpur, Alwar and Karavli. After this Rajasthan union was formed in which kingdoms of Boondi, Talwara, Pratapgarh, Shahpur, Banswara, Kota, Kishangarh, etc. were included in it.

Question 14.
Write down the development of India in economic and industrial fields after the independence.
Answer:
Many economic problems occurred in India due to division of the countries. Large part of wheat and rice producing areas of India went to Pakistan. Large part of irrigated land also went to Pakistan. So there was a shortfall of grains in India. In the same way large part of jute and cotton producing areas went over to India. There was a short fall of raw material for jute and textile industries. So Indian government started to find solution of these problems to improve economic condition of the country. That’s why Planning Commission was established in 1950 to achieve this objective. In this way the process of economic development started in the country which is still going on. This shadow can be seen in agricultural and industrial sectors as well.

Agriculture. India is a agriculture based country. Foodgrains are produced on 75% agricultural land of the country. Rice, wheat, peanut, sugarcane, maize, sunflower, etc. are important foodgrain crops. India made dams on all the important rivers for the development of country. These dams give water to agricultural land and stop floods to a great extent. These dams are helpful in producing electricity. These are known as river valleys. Nangal Dam, Damodar Valley Dam, Harikud Dam, Tungabhadra Dam and , Nagaijuna Sagar Dam are some of the important dams of the country.

Special steps were taken by the government to increase agricultural production. Farmers were told new methods of farming. Government gives good seeds and fertilizers to farmers. Poor farmers are given loans from Banks to improve agriculture. In this way government is trying to improve condition of agriculture.

Industry: Industrial development started in India even during British rule. Many Textile, Iron, Sugar, Matchstick, Cement industries were established in that age. But these industries were unable to develop fully because British hardly took care in development of Indian industry. But after independence, India started to spread industrial sector in the country. Engineering tools, Electrical goods, computers and related goods, medicine and industries of agricultural tools were established in the country. Many Multinational companies established their industries in the country. These industries have given employment to lakhs of skilled and semi-skilled labourers.

Indian government took special interest in Scientific and Industrial inventions. Many universities were set up to invent new tools, seeds, fertilizers, etc.

Question 15.
Explain the relationship of India and America.
Answer:
The United States of America is supreme among the great powers of the world. India’s relations with the USA never remained simple. These relations have been changed from time to time. After Indian independence, strained relations remained between both the countries over the issue of Kashmir and several other issues.

Following are the main reasons of strained relations between both the countries.

  1. the United States of America started to give more and more military help to Pakistan. India strongly opposed it but America hardly cared about it.
  2. Pakistan become the member of military alliances made by America but India refused to become member of these alliances.
  3. Bangladesh come into existence as a result of the Indo-Pakistan war in 1971 A.D. America tried to interfere in war in favour of Pakistan but India strongly opposed it.
  4. America established military bases in Pakistan. America has made military cantonments at Digo-Garcia island in Indian ocean. India also opposed it because c’ its security concerns.
  5. There are some basic differences among India and America on the issue of Nuclear Power. India is developing Nuclear power but America has strongly opposed it. Even America has stopped supply of nuclear fuel to India.
  6. India has not signed Nuclear Prolification Treaty (NPT) because it is not based on moral values. This treaty is partial. This treaty restricts those countries to make nuclear weapons who don’t have nuclear power. On the other side there is no such restrictions on Nuclear powers.

Actually Indian relations with America are strained due to these given reasons. But still they are not much strained. Both the countries are cooperating each other in economic, technological, scientific and cultural fields. In 1993 A.D. Bill Clinton become the President of USA and from then these relations are improving day by day. America helps India in economic sector as well. The USA and its economic institutions are playing a very important role in economic system of India in present age. We can expect better relations in near future as well.

II. Fill in the Blanks :

Question 1.
_______ was made the President of the Committee.
Answer:
Dr. Ambedkar

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 2.
Dr. Rajinder Prasad was the first _______ of India.
Answer:
President

Question 3.
In 1954 A.D _______ hand over Pondicherry, Chandernagar and Mahi Indian territories to India.
Answer:
French.

III. Write True or False in brackets given after each statement:

Question 1.
After getting independence, India constituted a committee of seven members for the drafting of Constitution.
Answer:
True

Question 2.
In the end of 1948 A.D. India occupied the French and Portugueses settlements which were situated in India.
Answer:
False

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 3.
After the independence, Indian government did not pay any attention towards her industrial development.
Answer:
False.

IV. Match the Words :

Question 1.

A B
1. The first Home Minister of India (i) Seven members
2. Members of Indian Constitution (ii) In 1999 A.D. Committee
3. Dispute of Kargil (iii) Sardar Vallabh Bhai Patel.

Answer:

A B
1. The first Home Minister of India (iii) Sardar Vallabh Bhai Patel.
2. Members of Indian Constitution (i) Seven members
3. Dispute of Kargil (ii) In 1999 A.D. Committee

V. Things To Do :

Question 1.
To know about the cultural similarities of India and her neighbour countries.
Answer:
Do it yourself.

PSEB 8th Class Social Science Guide India after Independence Important Questions and Answers

Multiple Choice Questions :

Question 1.
The Constituent Assembly of India started preparing the new Constitution in
(a) July 1946
(b) Dec. 1946
(c) Aug. 1947
(d) Jan. 1950
Answer:
(b) Dec. 1946.

Question 2.
When did India become Republic?
(a) 26 Aug, 1947
(b) 26 Jan, 1950
(c) 15 Aug, 1947
(id) 26 Nov, 1949
Answer:
(b) 26 Jan, 1950.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 3.
When were the Indian states reorganised?
(a) 1950
(b) 1953
(c) 1956
(d) 1959.
Answer:
(c) 1956.

Question 4.
On what basis, Indian states were reorganised in 1956?
(a) Wealth
(b) Population
(c) Natural resources
(d) Linguistic.
Answer:
(d) Linguistic.

Question 5.
Till today, _______ five year plans have been made.
(a) Ten
(b) Eight
(c) Twelve
(d) Nine
Answer:
(c) Twelve

Question 6.
Franchise is people’s right to _______
(a) Property
(b) Vote.
(c) Freedom
(d) Religion.
Answer:
(b) Vote.

Question 7.
Which of these problems was faced by the newly independent India?
(a) Problem of refugees
(b) Problem of division of Society
(c) Problem of development
(d) All of these.
Answer:
(d) All of these.

Question 8.
Which of these subjects was kept in Union List?
(a) Taxes
(b) Defence
(c) Foreign affairs
(d) All of these.
Answer:
(d) All of these.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 9.
Which of these subjects was in the State List?
(a) Medical
(b) Police
(c) Local bodies
(d) All of these.
Answer:
(d) All of these.

Question 10.
At the time of independence, the majority of Indians lived in
(a) Villages
(b) Towns
(c) Cities
(d) Metropolitans.
Answer:
(a) Villages.

Question 11.
Who said that, “In politics we have equality, and in social and economic life we will have inequality.”
(a) Jawaharlal Nehru
(b) Dr. B.R. Ambedkar
(c) Mahatma Gandhi
(d) Lai Bahadur Shastri.
Answer:
(b) Dr. B.R. Ambedkar.

Question 12.
_______ refugees come in India after independence?
(a) 5 million
(b) 6 million
(c) 8 million
(d) 10 million.
Answer:
(c) 8 million.

Question 13.
_______ princely states were there in India in 1947.
(a) 570
(b) 560
(c) 550
(d) 565.
Answer:
(d) 565.

Question 14.
India’s population in 1947 was _______
(a) 345
(b) 325
(c) 355
(d) 395.
Answer:
(a) 345.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 15.
Who was the permanent chairman of the Constituent Assembly?
(a) B.R. Ambedkar
(b) Dr. Rajendra Prasad
(c) Mahatma Gandhi
(d) Rajgopalchari.
Answer:
(b) Dr. Rajendra Prasad.

Fill in the Blanks :

Question 1.
_______ was made the Chairman of Drafting Committee.
Answer:
Dr. Ambedkar

Question 2.
Dr. Rajendra Prasad was the first _______ of India.
Answer:
President

Question 3.
In 1954 A.D gave Pondicherry, Chandranagar and Mahi to India
Answer:
France.

Tick the Right (✓) or Wrong (✗) Answer :

Question 1.
After Indian Independence, a drafting Committee was Constituted.
Answer:
(✓)

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 2.
At the end of 1948 A.D. India took control of all the areas which were under the Portugueese and French occupation.
Answer:
(✗),

Question 3.
After independence, India did not care about its industrial development.
Answer:
(✓).

Match the Following :

Question 1.

A B
1. First Home Minister of India (i) 1999
2. Members of Drafting Committee (ii) Sardar Patel
3. Kargil War (iii) Seven

Answer:

A B
1. First Home Minister of India (ii) Sardar Patel
2. Members of Drafting Committee (iii) Seven
3. Kargil War (i) 1999

Very Short Answer Type Questions

Question 1.
How many members were there of Drafting Committee of Indian Constitution? Who was its Chairman?
Answer:
There were seven members of Drafting Committee of Indian Constitution. The Chariman of this committee was Dr. B.R. Ambedkar.

Question 2.
Who was the first President of India?
Answer:
Dr. Rajendra Prasad was the first President of India.

Question 3.
Why small kingdoms were included in the nearby states in India?
Answer:
Indian government felt that small kingdoms would not be able to develop properly. That’s why they were included in the nearby states.

Question 4.
Which areas of India were under Portuguese possession at the time of Independence? When they were included in Union of India?
Answer:
Areas of Goa, Daman and Deu were under Portuguese possession at the time of Indian independence. On 20th December 1961 A.D. they were included in Union of India.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 5.
How many States and Union Territories are there in India?
Answer:
There are 28 States and 7 Union Territories in India.

Question 6.
When states were reorganized and how many States and Union Territories were formed?
Answer:
States were reorganized in November 1956 A.D. 14 States and 6 Union Territories were formed at that time.

Question 7.
Who were the first Governor-Generals of India and Pakistan?
Answer:
Lord Mountbetten and Mohammad Ali Jinnah respectively.

Question 8.
What was the impact of division of India on the people of Bengal and Punjab?
Answer:
Lakhs of people of Bengal and Punjab died due to division of India and lakhs had to leave their homes. Around 80 lakh people of eastern and western Punjab had to leave their lands, shops and other properties.

Question 9.
What is the main base of foreign policy of India?
Answer:
Peaceful co-operation.

Question 10.
Where Afro-Asian Conference of 1955 held in Indonesia? Name three Asian leaders participated in it.
Answer:
Afro-Asian Conference of 1955 was held at Bandug in Indonesia. Indian Prime Minister Pt. Jawahar Lai Nehru, Chau-in-lai of China and Sukarno of Indonesia took part in it.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 11.
Who were the founders of Non-Aligned Movement?
Answer:
Pt. Jawahar Lai Nehru of India, President of Ugoslavia Tito and President of Egypt Nasir were the founders of Non-Aligned Movement.

Question 12.
When Non-Aligned Movement was started? On which values it is based?
Answer:
Non-Aligned Movement started in 1961 A.D. It was based upon the principles of Panchsheel.

Question 13.
Give brief description of SAARC.
Answer:
‘SAARC was founded in 1985 A.D. Its full form is ‘SOUTH ASIAN ASSOCIATION OF REGIONAL COOPERATION’. Its objective was to produce economic cooperatio’n and mutual peace among South Asian countries.

Question 14.
What are the main social and economic problems of India?
Answer:
Communalism, casteism, linguism, poverty, unemployment, illiteracy, population explosion, etc.

Question 15.
What is the problem of Linguism?
Answer:
Peopje speaking different languages live over here in India. Problem in this relation is that some people consider their language as superior than the other languages.

Question 16.
Give two evil consequences of increasing population.
Answer:

  1. Increasing population is the basic reason of poverty and unemployment.
  2. Development plans of government either fail or they move on a slow pace.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 17.
When and why war started between India and China?.
Answer:
War between India and China started in 1962 A.D. due to border dispute.

Question 18.
Between whom Lahore agreement took place? What was its objective?
Answer:
Lahore agreement took place between Indian Prime Minister Atal Behari Vajpai and Pakistani Prime Minister, Nawaz Sharif. Its objective was to resolve mutual disputes of India and Pakistan peacefully.

Short Answer Type Questions

Question 1.
How was the Indian Constitution framed?
Answer:
After independence, India made a committee of 7 members to frame the Constitution. It was assigned the work of drafting the Constitution. Dr. B.R. Ambedkar was made its chairman. This committee made the draft and produced in front of constituent assembly on 21st February, 1948 A.D. Discussion on this draft was started from 4th Nov. 1948. Assembly had to go through 11 meetings for this. Around 2473 amendments were produced during this discussion age and some of them were accepted. This Constitution was passed on 26th November, 1949 A.D. and was implemented on 26th January 1950 A.D.

Question 2.
Write a note on ‘Panchsheel’.
Answer:
India made an agreement with the Chinese Prime Minister Chau-in-lai in 1954 A.D. This agreement was based on five principles. These principles are given below :

  1. To accept peaceful co-existence.
  2. Not to attack each other.
  3. Not to interfere in each other’s matter.
  4. To obey the concept of equality and cooperation for mutual interests.
  5. To respect mutual sovereignty and regional integrity.

Question 3.
How India made free its areas from the possession of French and Portuguese after independence?
Answer:
Indian areas of Goa, Daman and Diu were under Portuguese possession. In the same way Pondicherrey, Chandranagar and Mahi were under French rule. French gave back Indian areas to India in 1954 A.D. but Portuguese refused to do so. In the end Indian government was forced to use military to take -possession of its areas. On 20th December 1961 A.D., Portuguese establishments of Goa, Daman and Diu were included in the Union of India. Goa was made a state on 30th May, 1987 A.D. and Damap and Diu were made Union territories.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 4.
Why and how states were reorganized after independence?
Answer:
Indians started to demand reorganize states on the basis of language and culture even during British rule. After independence, one Telugu person Ramulu demanded to reorganize states on linguistic basis, kept indefinite fast as and was died. So constitutional amendment took place and Telugu spoken areas were separated from Madras and was given the name of Andhra Pradesh. One commission with three members was appointed to reorganize other states. States were reorganized in Nov. 1956 on the basis of recommendations of commission. 14 states and 6 union territories were formed.

Question 5.
Describe the role of India in U.N.O.
Answer:
India is an active member of the U.N.O. (United Nations Organisation). India has sent its forces with peace keeping forces of U.N.O. in many disturbed areas of the world.

India has also contributed a lot in many institutions and agencies of U.N.O. For example Vijay Laxmi Pandit became the member of General Assembly of U.N.O. in 1963 A.D. Shashi Tharoor is the Under Secretary of Communication and Public Information of U.N.O. India is also a member of Security Council. India gets aid of U.N.O. every year as well.

Question 6.
Write a note on problem of Casteism and Poverty.
Answer:
Problem of Casteism. Problem of casteism is one of the main obstacles in the way of our national unity. Some people always hate the people of other castes. Even politicians and political parties take the help of caste to get support of the people. But it is required from us that all the people should be equally treated. According to Article 17 of Constitution, untouchability is restricted in any form.

Problem of Poverty. The Problem of poverty is one of the largest obstacles in the way of progress of the country. Indian people are so poor that they are unable to get proper food of one day. Main reasons of poverty are increasing population, less agricultural production and unemployment. Government has tried a lot to reduce poverty.

Question 7.
Briefly describe the problem of unemployment in India.
Answer:
Problem of unemployment is increasing day by day because number of unemployed persons is increasing. Most of the unemployment exists among literate people. Government is trying a lot to resolve this problem. Retired servicemen, literate unemployed are given loans from government so that they could start their own business. Retirement age of job is reducing so that more and more people could get employment. Additional occupations like rearing of cattle, pigs, honey bees, etc. are being encouraged, Training and loan facilities are also provided to them.

PSEB 8th Class Social Science Solutions Chapter 23 India after Independence

Question 8.
Write a note on problem of Inflation in India.
Answer:
Inflation is a world-wide problem in today’s age. But this problem has taken serious form in India. Today everything available in the market is expensive. Prices of goods are increasing day by day. As a result most number of people are unable to fulfil their basic needs of daily life. That’s why the government should take some concrete steps to control increasing inflation. Government should implement such plans in the country with which Inflation could be reduced.

Long Answer Type Question

Question 1.
Describe in detail about problems of illiteracy and the increasing population.
Answer:
1. Illiteracy. More than 23 crore people of India are illiterate. Around 60 women out of 100 are illiterate. Illiteracy gives rise to unemployment which becomes a reason for poverty. An illiterate person hardly knows about the progression opportunities available in the country. Except this democratic system will become successful if people would be literate.

An illiterate person is unaware of his rights and duties as well.
Governmental Efforts: Indian Government is taking certain steps to remove illiteracy from the country :

  • There is a provision in our Constitution to give free and compulsory education to children upto the age of 14 years.
  • Indian government gives scholarships to poor and intelligent students.
  • The Indian government has also started adult education in the country. National Adult Education Programme was started on 2nd October 1978 A.D. National Literacy Mission was started in 1988 A.D. Many Adult education centres were established under this mission.
  • Many educational programmes, related to illiterate adults, are being broadcast on All India Radio and Doordarshan. Their main objective is to literate every person in the country.

2. Increasing Population. India is facing a problem of the increasing population these days. The speed of the increasing population in India is too much that it is very difficult to stop this speed by the government. According to the census of 2011 A.D., India’s population was 121.02 crores. Our population is increasing by lakhs every year.

Causes: There are certain reasons for increasing population in the country:

  • The death rate is decreasing due to the improvement of medical facilities. About 25 years ago this death rate was 33 per thousand. But now it has been reduced to 9 per thousand. In earlier times, many diseases were there like the plague, malaria, etc. because of which thousands of people used to die. But now these diseases have been controlled to a great extent.
  • Marriage is less age is one of the reasons for the increasing population. Many rural families used to prefer child marriages which result in the growth of the population.
  • People don’t like to use family planning due to ignorance and religious reasons.
  • Many poor people think that more children will help in an increase in the income of the family. That’s why parents like to give birth to more children.

Losses and solution. The increasing population is the basic reason for many problems like poverty, unemployment, etc. All the developmental plans become useless with the increasing population. These problems could be solved at a government level. People could be told about the losses of increasing population and government can propagate in favour of small family.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 8 Cell Structure and Functions Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 8 Cell Structure and Functions

PSEB 8th Class Science Guide Cell Structure and Functions Textbook Questions and Answers

Answer These

Question 1.
Indicate whether the following statements are True [T] or False [F].
(a) Unicellular organisms have one-celled bodies.
Answer:
True

(b) Muscle cells are branched.
Answer:
False

(c) The basic living unit of an organism is an organ.
Answer:
False

(d) Amoeba has irregular shape.
Answer:
True

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 2.
Make a sketch of the human nerve cell. What function do nerve cells perform ?
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 1
Functions of Nerve Cell:

  1. It receives and transfers messages.
  2. It control and co-ordinate the functioning of different parts of the body.

Question 3.
Write short notes on the following :
(a) Cytoplasm
(b) Nucleus of a cell.
Answer:
(a) Cytoplasm.
It is a jelly-like fluid present inside the cell membrane. Various cell organelles are present in it. It contains water, sugar, minerals, lipids proteins etc.

(b) Nucleus.
As true nucleus is present in all the eukaryotic cells except mammalian RBCs, sieve tube cells, tracheids and vessels. It is formed of four components:
(i) Nuclear Membrane.
It is a two-layered envelope around the nuclear sap. It is porous (with nuclear pores) and semi-permeable membrane. Outer membrane is studded with ribosomes. It regulates exchange of materials between nucleoplasm and cytoplasm.

(ii) Nucleoplasm.
It is a semifluid colloidal substance in which nucleoli and chromatin fibres are present. It acts as nuclear skeleton and forms spindle for the cell division.

(iii) Nucleolus.
It is dense, spherical, naked and darkly stained structure and it is site of formation and store house of RNA.
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 2
(iv) Chromatin Fibres.
These are long, fine and darkly stained threads which collectively form nuclear reticulum. During prophase of mitosis and meiosis, these condense to form a specific number of rods, called chromosomes. These are embedded with genes which are chemically formed of DNA and act as units of heredity and variation. They also help in the synthesis of structural and enzymatic protein.

Question 4.
Which part of the cell contains organelles ?
Answer:
Cytoplasm contains organelles.

Question 5.
Make sketches of animal and plant cells. State three differences between them.
Or
State four differences between animal and plant cells.
Answer:
Animal cells differ from plant cells in the following definite ways :

Plant cells Animal cells
1. Plant cells have cell wall made up of cellulose. 1. Animal cells have no such walls and no cellulose.
2. Plant cells have chloroplasts. 2. Animal cells do not possess the chloroplasts.
3. Plants cells have thin cytoplasm and large vacuole. 3. Animal cells have thick cytoplasm with no vacuole.
4. Centrosome absent. 4. Centrosome present.
5. Reserve food is in the form of starch. 5. Reserve food is in the form of glycogen and param sylum.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 3

Question 6.
State the difference between eukaryotes and prokaryotes.
Answer:
Eukaryotes.
These are the organisms whose cells contain well defined nucleus with a clear nuclear membrane. Examples are onion cells, cheek cells.

Prokaryotes.
These are the organisms whose cells have no definite nucleus i.e. without nuclear membrane. Examples are bacteria, blue green algae.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 7.
Where are chromosomes found in a cell ? State their function.
Answer:
Chromosomes are found in nucleus of a cell. Chromosomes carry genes and help in inheritance or transfer of characters from the parents to the offspring.

Question 8.
‘Cells are the basic structural units of living organisms’. Explain.
Answer:
As a building cannot be constructed without bricks. Similarly, a body of living organism has basic structural unit such as cell. Cells are of different size, shapes and group together to form organs, organ systems etc.

Question 9.
Explain why chloroplasts are found only in plant cells ?
Answer:
Chloroplast are green coloured plastids. They impart green colour to plants and only plants make use of green colour to synthesis food.

Question 10.
Complete the crossword with the help of clues given below.
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.

Down
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 4
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 5

PSEB Solutions for Class 8 Science Cell Structure and Functions Important Questions and Answers

Multiple Choice Questions

Question 1.
A slide is given in the figure below. What does this show ?
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 6
(a) Cork cells
(b) Onion membrane
(c) Unicellular organism
(d) Multicellular Organism.
Answer:
(b) Onion membrane.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 2.
What is the name of basic structural unit in living organism ?
(a) Tissue
(b) Organ of body
(c) Cell
(d) Molecule.
Answer:
(c) Cell.

Question 3.
Which out of the following cell-organ is found in plants only ?
(a) Mitochondria
(b) Chloroplast
(c) Cell membrane
(d) Nucleus
Answer:
(b) Chloroplast.

Question 4.
Which organism is not unicellular ?
(a) Bacteria
(b) Amoeba
(c) Paramecium
(d) Algae or mould
Answer:
(d) Algae or mould.

Question 5.
Which of the cell organelle synthesise protein ?
(a) Lysosome
(b) Chromosome
(c) Ribosome
(d) Centrosome
Answer:
(c) Ribosome.

Question 6.
Who discovered cell ?
(a) Robert Hook
(6) M.J. Schleiden
(c) Schwann
(d) Robert Brown
Answer:
(a) Robert Hook

Question 7.
Which cell organelle is called suicidal bag ?
(a) Ribosome
(b) Lysosome
(c) Chromosome
(d) Centrosome
Answer:
(b) Lysosome

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 8.
Which out of the following is unicellular organism?
(a) Amoeba
(b) Paramecium
(c) Bacteria
(d) All of these.
Answer:
(d) All of these.

Question 9.
Which is the power-house of cell?
(a) Centrosome
(b) Chloroplast
(c) Mitochondria
(d) Ribosome.
Answer:
(c) Mitochondria.

Question 10.
Name a human cell which can change its shape.
(a) White blood cells
(b) Red blood cells
(c) Platelets
(d) Plasma
Answer:
(b) Red blood cells.

Question 11.
Which organ of the cell is found in plant cell only?
(a) Cell wall
(b) Chromosome
(e) Nucleus
(d) Cytoplasm
Answer:
(a) Cell wall.

Question 12.
Which is the longest cell of human body?
(a) Nerve cell
(b) Muscular cell
(c) Red blood cells ,
(d) White blood cells
Answer:
(a) Nerve cell.

Question 13.
Of what the cell wall is made?
(a) Fat
(b) Cellulose
(c) Protein.
(d) Mineral Salt.
Answer:
(b) Cellulose.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Very Short Answer Type Questions

Question 1.
Fill in the blanks.
1. The cell is the …………………. and functional unit of organism.
2. Cell wall is found in ……………….. cells.
3. Power house of the cell is ………………….
4. Amoeba and Paramecium consists of a single …………………
5. Plastids are present only in ……………….. cells.
Answer
1. structural
2. plant
3. mitochondrion
4. cell
5. plant.

Question 2.
Choose the correct answer.
1. Suicidal bags of cells are ?
(a) Lysosomes
(b) Chloroplast
(c) Mitochondria
(d) Ribosomes.
Answer:
(a) Lysosomes

2. Plant cells do not have:
(a) Cell wall
(b) Centrosomes
(c) Plastids
(d) Mitochondria.
Answer:
(b) Centrosomes.

Question 3.
What is structural and functional unit of life ?
Answer:
Cell.

Question 4.
What is the contribution of Robert Brown in cell biology ?
Answer:
He discovered nucleus in the cells of orchid.

Question 5.
Who proposed the cell theory ?
Answer:
M.J. Schleiden and Theodore Schwann.

Question 6.
Name the smallest and largest cell.
Answer:
Smallest cell – Mycoplasma.
Largest cell – Ostrich egg.

Question 7.
Name the smallest and largest cell of human body.
Answer:

  1. Smallest cell – nephron.
  2. Largest cell – neuron.

Question 8.
Who called the protoplasm as the physical basis of life ?
Answer:
Huxley.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 9.
Give the contribution of Rudolf Virchow in the field of biology.
Answer:
He stated “omnis cellula e cellula” which means new cells are formed by the growth and division of pre-existing cells.

Question 10.
What are two types of cells on the basis of nature of nucleus ?
Answer:
Prokaryotic and Eukaryotic cells.

Question 11.
What is nucleoid ?
Answer:
Nucleoid. It is incipient nucleus of prokaryotes like bacteria and blue-green algal cells and is without nuclear membrane.

Question 12.
What is contribution of Robert Hooke in the field of cell biology ?
Answer:
Robert Hooke discovered the cell.

Question 13.
What are the three functional regions of a cell ?
Answer:
Plasma membrane, cytoplasm, nucleus.

Question 14.
Give the primary function of plasma membrane.
Answer:
It regulates exchange of material between cytoplasm and extra-celluar fluid.

Question 15.
Name the smallest sized cell organelle.
Answer:
Ribosome.

Question 16.
Which cell organelle is called suicidal bag ?
Answer:
Lysosome.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 17.
Name the largest sized cell organelle.
Answer:
Plastids.

Question 18.
Which cell organelle is called cell centre ?
Answer:
Centrosome.

Question 19.
What are organs ?
Answer:
Organs. Various body parts of animals and plants are called organs.

Question 20.
Who coined the word ‘Cell’ ?
Answer:
Robert Hooke.

Question 21.
Why Robert Hooke coined the word cell ?
Answer:
Robert Hooke was excited when he observed spaces in a cork slice those appeared like honeycomb. He called these compartments as cells.

Question 22.
Name some organs of plants.
Answer:
Roots, stem, leaves, flower, fruit.

Question 23.
Write examples of unicellular organisms.
Answer:
Amoeba, Paramecium, Bacteria, etc.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 24.
What is size of the smallest cell ?
Answer:
0.1 micron (μm) i.e. ten thousandth part of a millimetre.

Question 25.
What is yellow yolk in the egg of a hen ?
Answer:
It represents single cell.

Question 26.
Write the size of largest cell observable with naked eyes.
Answer:
170 mm.

Question 27.
What are cell organelles ?
Answer:
The parts of a cell are called cell organelles.

Question 28.
What role does cell membrane play in a cell ?
Answer:
Cell membrane encloses a liquid substance known as protoplasm. It regulates the flow of substances both into the cell and out of it.

Question 29.
Name four major elements responsible for protoplasm.
Answer:
Carbon, Hydrogen, Oxygen, Nitrogen.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 30.
What is nucleoplasm ?
Answer:
Nucleoplasm. It is the liquid protoplasm in the nucleus.

Question 31.
Who controls the activities of a cell ?
Answer:
Nucleus.

Question 32.
What do chromosomes do ?
Answer:
Chromosomes help in inheritance or transfer of characters from the parents to next generation.

Question 33.
What are chloroplasts ?
Answer:
The green plastids in the plants are called chloroplasts.

Question 34.
What is the shape of mitochondria ?
Answer:
Rod-shaped or spherical.

Question 35.
Name the power house of a cell.
Answer:
Mitochondria.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Short Answer Type Questions

Question 1.
What is a cell ?
Answer:
Cell.
Just as the bricks are the units of all types of houses, the cells are the units or building blocks of living organisms. Animals and plants like ant, housefly, dog, elephant, sunflower, neem etc. consist of cells.

Question 2.
Write the names of cell organelles.
Answer:
Cell Organelles.
Cell organelles are living strictures of cytoplasm. These include : Endoplasmic reticulum, Golgi apparatus, mitochondria, ribosomes, lysosomes, peroxisomes, plastids, sphaerosomes, glyoxysomes, centrosome. microtubules, microfilaments, cilia and flagella.

Question 3.
What is the difference between the plasma membrane and cell wall ? Give the functions of each one.
Answer:

Characters Plasmsa membrane Cell Wall
1. Occurrence Around the protoplasm of all the cells. Outside the plasma membrane in plant cells, bacteria, blue-green algae, fungi etc.
2. Nature Thin and selective permeable. Thick and freely permeable.
3. Chemistry Lipoproteinous and trilaminar. Formed of cellulose hemicellulose, pectin, water, etc.
4. Function Regulates the exchange of materials between cytoplasm and extracellular fluid. It is protective and supportive in function. It provides definite shape and prevents evaporation of water.

Question 4.
Which cell organelle is called “suicidal bag” and why ?
Answer:
Lysosome is commonly called suicidal bag of cell. It is so as it contains hydrolytic enzymes which help in digestion of foreign food or bacteria (by heterophagy) ; or reserve food or certain cell organelles (by autophagy) ; or the whole cell after the cell death (by autolysis).

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 5.
Which cell organelle is called “power house” of the cell ? Write about its function briefly.
Answer:
Mitochondrion is commonly called “power house” of the cell because it is site of oxidative breakdown of glucose in aerobic cell respiration to produce energy- rich ATP molecules. One mole of glucose, in aerobic respiration, produces 36 ATP molecules.

Question 6.
Define the following terms :
(a) Protoplasm
(b) Cytoplasm
(c) Nucleoplasm.
Answer:
(a) Protoplasm is the physical basis of life and lies inside the cell membrane. It includes both cytoplasm and nucleoplasm.

(b) Cytoplasm lies between the cell membrane and nucleus. It contains various types of cell-organelles and cell-inclusions. It undergoes cyclosis. It is the site of protein synthesis, glycolysis, etc.

(c) Nucleoplasm lies inside the nucleus and contains only nucleoli and chromatin fibres. It does not undergo cyclosis. It forms spindle during cell division.

Question 7.
Draw a labelled diagram of plant and animal cell.
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 7

Question 8.
Describe the variations in shape and size of cells.
Answer:
The cells are generally round or spherical in shape. However, there is lot of variations in shape of cells. These can be cuboidal and columnar. Some of the animal cells are long and branched as in nerve cells.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 9.
What are unicellular and multicellular organisms ?
Answer:
Unicellular Organisms. The organism whose body is made of only a single cell is called a unicellular organism, e.g. Amoeba, Paramecium, Chlamydomonas, Yeast, Euglena etc.
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 8
Multicellular Organisms. The organisms whose body is made of many cells is called a multicellular organisms, e.g. Man, Hydra, Dog, Elephant etc.

Question 10.
WTiat are organs and organ systems ?
Answer:
Organ. A group of tissues which perform a definite function of the body is called an organ.
Organ System. A group of organs which do a big job is called an organ system.

Question 11.
Draw the diagrams of different kinds of cells.
Answer:

Question 12.
How was the first cell discovered?
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 10
Robert Hooke in 1665 observed slices of cork under a simple magnifying device. Cork is part of the bark of a tree. He took thin slices of cork and observed them under his microscope. He noticed partitioned boxes or compartments in the cork slice. These boxes appeared like a honey comb.

He also noticed that one box was separated from the other by a wall or partition. Hooke coined the term ‘cell’ for each box. Cell in Latin means ‘hollow space.’

Question 13.
Discuss about the various shapes of cells.
Answer:
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 11
Generally cells are round, spherical or elongated. Some cells are long and pointed at both ends. They exhibit spindle shape. Cells sometimes are quite long and thread like. Some are branched like the nerve cell or neuron.

PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions

Question 14.
Differentiate between unicellular and multicellular organisms.
Answer:
Differences between unicellular and multicellular organisms.

Unicellular Organisms Multicellular Organisms
1. These organisms are made of only one cell. 1. These organisms are made of many cells.
2. All functions of body are performed by only a single cell. 2. Each function of the body is performed by a group of special cells.
3. Cilia are found.

Examples. Amoeba, Paramecium etc.

3. Cilia are not found.

Examples. Almost all animals.

Long Answer Type Questions

Question 1.
Describe the structure of a typical cell in detail.
Answer:
Structure of cell
A cell is the basic unit of life. It is capable of performing all functions of life and to fulfil all the functions, cell is made up of different parts. Basically, a cell is formed of three parts:
1. Cell membrane or plasma membrane
2. Nucleus.
3. Cytoplasm.

The cytoplasm is surrounded by cell membrane and nucleus constitutes the protoplasm of a cell. The typical structure of plant and animal cells are shown ahead:

1. Cell Membrane.
It is a delicate, thin membrane. It is also called plasma membrane. It forms the outermost layer in animals but in plant cells an additional membrane is present. It is called cell membrane in animal’s cell and cell wall in plant’s cell. Cell membrane has following functions:
(i) It provides shape to the cell.
(ii) It allows the flow of some substances into the cell and out of the cell.
(iii) It acts as a barrier to protect internal parts.
PSEB 8th Class Science Solutions Chapter 8 Cell Structure and Functions 12

2. Nucleus.
The oval or spherical structure, which is the controlling centre of all activities of the cell is called nucleus. Nucleus is made up of following parts:
(i) Nuclear Membrane. It is the membrane having pores which separates contents of nucleus from cytoplasm.
(ii) Nucleoplasm. The fluid present in nucleus is called nucleoplasm.
(iii) Nucleolus. Small spherical body made up of nucleoprotein. RNA is also present in nucleus.
(iv) Chromatin Material. Several thread like structures forming a network are present in nucleoplasm. Chromatin material is in the form of chromosomes which carries genes on it.

The nucleus has following functions:
Chromatin material of nucleus transmits characters from one generation to other.
It contains informations for carrying out all basic functions.

3. Cytoplasm.
The jelly like fluid inside the membrane of cell is cytoplasm. All tiny structures performing different functions, are present in it. These are called organelles.

It also contains water, sugar, minerals, lipids, proteins etc. The various cell organelles present in cytoplasm are:
(i) Mitochondria. They are commonly called Tower house of the cell’ because they help in release of energy from food. They also store energy. Mitochondria (singular mitochondrion) are oval or rod shaped organelle bounded by two membranes.

(ii) Endoplasmic Reticulum. A complex network of membranes which are present either attached to nucleus or free from it are endoplasmic reticulum. Its network extends from nuclear membrane to cell membrane. It helps in protein synthesis and also in transport of various substances.

(iii) Plastids. These organelles are present only in plant cells. These are of three types:
(а) Chloroplasts. Green coloured plastids are chloroplasts. The green colour is due to the presence of pigment chlorophyll. They are commonly known as ‘Kitchen of the’ cell’ because chloroplasts are the site of photosynthesis i.e. process of making food.

(b) Leucoplasts. Colourless plastids are called leucoplasts. These are present in the roots and underground modified stems.

(c) Chromoplasts. These are coloured plastids. These are present mainly in flowers, petals and fruits.

(iv) Golgi Bodies. These are membrane-bound, piles of many flattened sacs. In plants, Golgi bodies are known as dictyosomes. They are mainly secretory in function.

(v) Vacuoles. The fluid-filled organelles present in a cell are vacuoles. In-plant cells, vacuoles are few in number and larger in size whereas, in animals, they are more in number and smaller in size. They maintain the turgidity of plants cells. Vacuoles also serve as a waste deposit bin in which unwanted materials may be diverted.

(vi) Lysosomes. Small spherical bodies having a single membrane are lysosomes. They sacrifice their own selves to destroy and digest various materials. They are also called ‘suicidal bags’. Plant cells do not have lysosomes.

(vii) Ribosomes. These are small rounded bodies that are present free or attached with the endoplasmic reticulum. They perform the function of protein synthesis.

(viii) Centrosome. It is a rod-like structure. It occurs close to the nucleus and helps in cell division.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 3 Synthetic Fibres and Plastics Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics

PSEB 8th Class Science Guide Synthetic Fibres and Plastics Textbook Questions and Answers

Exercises

Question 1.
Explain why some fibres are called synthetic.
Answer:
Some fibres are called synthetic fibres because they are not obtained from natural sources. They are made by human beings. The raw materials used for preparing synthetic fibres are petrochemicals, which in turn are produced from fossil fuel, petroleum.

Question 2.
Mark (✓) the correct answer.
Rayon is different from synthetic fibres because
(a) it has a silk-like appearance
(b) it is obtained from wood pulp
(c) its fibres can also be woven like those of natural fibres.
Answer:
(b) It is obtained from wood pulp.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 3.
Fill in the blanks with appropriate words.
(а) Synthetic fibres are also called …………… or ……………….. fibres.
(b) Synthetic fibres are synthesised from raw material called ………………. .
(c) Like synthetic fibres, plastic is also a ………………… .
Answer:
(a) Man made, artificial
(b) Petrochemicals
(c) Synthetic.

Question 4.
Give examples which indicate that nylon fibres are very strong.
Answer:
Parachutes, ropes for climbing, tents made of nylon.

Question 5.
Explain why plastic containers are favoured for storing food.
Answer:
Advantages of using plastic containers for storing food:

  1. They do not react with food, air and water.
  2. They are strong and light in weight.
  3. They can have different sizes, shapes and colours.

Question 6.
Explain the difference between thermoplastic and thermosetting plastics.
Answer:
Differences between the Thermoplastics and Thermosetting Plastics

Thermoplastics Thermosetting plastics
1. It can bend easily. 1. It cannot bend but breaks.
2. On heating, it gets deformed. 2. Heating has no affect on it.
3. It can be used again and again. 3. It cannot be reused.
4. It can be moulded into various shapes on heating. Examples : Polythene, PVC. 4. It can be moulded only once, on heating.

Examples : Bakelite, Melamine.

Question 7.
Explain why the following are made of thermosetting plastics.
(а) Saucepan handles
(b) Electric plugs/switches/plug boards
Answer:
(a) Saucepan handles are made of thermosetting plastics because plastic is bad conductor of electricity, fire resistant and heat tolerant.

(b) Electric plugs/switches/plugboards are made of thermosetting plastics because this plastic is bad conductor of electricity and durable.

Question 8.
Categorise the materials of the following products into ‘can be recycled’ and ‘cannot be recycled’.
Telephone instruments, plastic toys, cooker handles, carry bags, ball point pens, plastic, bowls, plastic covering on electric wires, plastic chairs, electrical switches.
Answer:
Can be recycled. Plastic toys, carrybags, ball point pens, plastic bowls, plastic chairs, plastic covering on electric wires.
Cannot be recycled. Telephone instruments, cooker handles, electrical switches.

Question 9.
Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material ? Advise Rana, giving your reason.
Answer:
Rana should buy cotton shirts.
Preference of cotton clothes to synthetic materials in summers.

  1. Cotton clothes are porous while synthetic materials are non-porous or air resistant.
  2. Cotton clothes soak sweat and give a dry feeling while synthetic clothes have little water absorbing property.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 10.
Give examples to show that plastics are non-corrosive in nature.
Answer:
Plastics are non-corrosive in nature. Plastics do not react with air, water etc. so, they do not get corroded.
For example –

  1. Different chemicals are stored in plastic bottles.
  2. Water is kept into plastic bottles.
  3. Pickles and food items are stored in plastic containers.

Question 11.
Should the handles and bristles of a toothbrush be made of the same material ? Explain your answer.
Answer:
No, different materials should be used for making handles and bristles of toothbrush because bristles help in cleaning teeth and handle is just for support. Bristles must be soft and delicate and powerful while handle should be hard and rigid.

Question 12.
‘Avoid plastics as far as possible’. Comment on this advice.
Answer:
Plastics are not environment friendly. They release poisonous gases on burning. They are non-biodegradable, so pollute soil or water in which they are dumped. Therefore, use of plastic should be avoided as far as possible.

Question 13.
Match the terms of Column A correctly with the phrases given in Column B.

Column A Column B
(i) Polyester (a) Prepared by using wood pulp
(ii) Teflon (b) Used for making parachutes and stockings
(iii) Rayon (c) Used to make non-stick cookwares
(iv) Nylon (d) Fabrics do not wrinkle easily

Answer:

Column A Column B
(i) Polyester (d) Fabrics do not wrinkle easily
(ii) Teflon (c) Used to make non-stick cookwares
(iii) Rayon (a) Prepared by using wood pulp
(iv) Nylon (b) Used for making parachutes and stockings

Question 14.
‘Manufacturing synthetic fibres is actually helping conservation of forests’. Comment.
Answer:
Natural fibres are obtained from natural resources i.e. natural plants. But synthetic fibres are obtained from other materials. So, synthetic fibres are not dependent on natural vegetation or crops grown in the field. Thus manufacturing synthetic fibres actually helps conservation of forests.

Question 15.
Describe an activity to show that thermoplastic is poor conductor of electricity.
Answer:
PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics 1
Activity.
Take a few samples of thermoplastic such like polythene, PVC, Nylon, Polystyrene etc.
Now set up the circuit as shown in fig. and insert a piece of Nylon between the two terminals A and B of copper wire. If bulb starts glowing then it is good conductor otherwise it is a bad conductor. Repeat the experiment using different samples of thermoplastics.
In each case, bulb would not glow indicating that thermoplastics are bad conductor of electricity.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

PSEB Solutions for Class 8 Science Synthetic Fibres and Plastics Important Questions and Answers

Multiple Choice Questions

Question 1.
In the following diagram, a boy is seen using rope for going up a rock. Tell rope made of which material is most suitable for this purpose ?
PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics 2
(a) Cotton
(b) Wood
(c) Nylon
(d) None of these.
Answer:
(c) Nylon.

Question 2.
Which of the following is called artificial silk ?
(a) Rubber
(b) Teflon
(c) Rayon
(d) Polythene.
Answer:
(c) Rayon.

Question 3.
…………… is used for making polyester clothes.
(a) P.E.T.
(b) Acrvline
(c) Terrylene
(d) None of these.
Answer:
(c) Terrylene.

Question 4.
Today while studying in the class Nisha came to know that there is such a type of plastic which melts when heated. Name this plastic. (From Board M.Q.P.)
(a) Plastic
(b) Thermoplastic
(c) Acrylic
(d) All of the above.
Answer:
(b) Thermoplastic.

Question 5.
Which out of the following is natural fibre ?
(a) Rayon
(b) Terylene
(c) Wool
(cl) Nylon.
Answer:
(c) Wool.

Question 6.
Which out of the following fibres is made by man ?
(a) Cotton
(b) Wool
(c) Rayon
(d) Silk.
Answer:
(c) Rayon.

Question 7.
Which out of the following is biodegradable ?
(a) Metal
(b) Plastic
(c) Paper
(d) All of these.
Answer:
(c) Paper.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 8.
Which of the following material is used to make ropes ?
(a) Cotton
(b) Wool
(c) Nylon
(d) None of the above.
Answer:
(c) Nylon.

Question 9.
Which type of thermoplastic is used to make switches, which is poor conductor of heat and electricity ?
(a) Nylon
(b) Backelite
(c) Melamine
(d) Polythene
Answer:
(b) Backelite.

Question 10.
Which out of the following is thermoplastic ?
(a) Nylon
(b) Polythene
(c) Acrylic
(d) Backelite
Answer:
(d) Backelite.

Question 11.
Synthetic fibres are made from small units called:
(a) Cell
(b) Molecules
(c) Polymer
(d) None of the above.
Answer:
(c) Polymer.

Question 12.
Sericulture is the bringing up of which creature ?
(a) Sheep
(b) Goat
(c) Hare
(d) Silk worm
Answer:
(d) Silk worm

Question 13.
Natural Polymer is:
(a) Rayon
(b) Cotton
(c) Nylon
(d) Polyster
Answer:
(b) Cotton.

Very Short Answer Type Questions

Question 1.
Name few natural fibres.
Answer:
Cotton, wool, silk.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 2.
Name a natural polymer.
Answer:
Cellulose.

Question 3.
Name a fibre which is silk like but man made.
Answer:
Rayon.

Question 4.
Which fibre is obtained from woodpulp ?
Answer:
Rayon.

Question 5.
In which year, Nylon was made ?
Answer:
In 1931.

Question 6.
Which fibre was made from coal, air and water ?
Answer:
Nylon

Question 7.
Of which fibre, parachutes and tents are made of ?
Answer:
Nylon

Question 8.
What is PET ?
Answer:
PET. It is a form of Polyester.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 9.
Why do parachutes and ropes for climbing rocks are made of Nylon ?
Answer:
Due to its strength.

Question 10.
Give few characteristics of plastics.
Answer:
Plastics can be recycled, reused, coloured, melted, rolled into sheets or made into wires.

Question 11.
What are Polythene and PVC ?
Answer:
Thermoplastics.

Question 12.
Bakelite is an example of which type of plastic ?
Answer:
Thermosetting plastic.

Question 13.
Where is Teflon used ?
Answer:
For making kitchen cookware and tape sealing.

Question 14.
Which of these fibres is costly-wool, rayon ?
Answer:
Wool.

Question 15.
Why does hot water deform plastic bottles ?
Answer:
Because they are made of thermoplastic, which melts on heating.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 16.
Which thermosetting material is versatile, heat resistant and fireproof ?
Answer:
Melamine.

Question 17.
Why is plastic used in cars, aircrafts etc. instead of metals ?
Answer:
Because it is lighter than metals.

Question 18.
Why are plastic containers convenient to use ?
Answer:
Plastic containers are light, cheap, strong and can be handled easily.

Question 19.
Which synthetic fibre resembles wool ?
Answer:
Acrylic.

Question 20.
Give two reasons for prefering synthetic fibres over natural fibres.
Answer:

  1. Durability and
  2. affordability.

Question 21.
Give one disadvantage of synthetic fibres.
Answer:
They melt on heating.

Question 22.
Which substances are non-biodegradable ?
Answer:
Non-biodegradable substances: Those substances which cannot be decomposed by bacteria are called non-biodegradable substances.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 23.
Which material or thing is responsible for choking drains and death of herbivores ?
Answer:
Polythene bags.

Question 24.
What is 4R principle ?
Answer:

  1. Reduce,
  2. Reuse,
  3. Recycle and
  4. Recover.

Question 25.
Plastics are non-biodegradable. Are they environment friendly or environment non-friendly ?
Answer:
Environment non-friendly.

Short Answer Type Questions

Question 1.
What are polymers ? Give an example of natural polymer. Are polymers found in nature ?
Answer:
Polymer.
A Polymer is a long chain consisting of lakhs of small units (molecules). It is made by combining together small molecules of chemical substances. Cellulose is natural polymer.

Polymers are found in nature. As for example, cotton is a natural fibre which in fact is cellulose. Cellulose is made up of large units of glucose. Similarly, wood pulp is cellulose from which rayon is manufactured. Therefore, rayon also a polymer.

Question 2.
What are synthetic fibres ?
Answer:
Synthetic Fibres.
The fibres other than natural fibres which are made by human beings are called synthetic fibres.
These are made of very large units which in turn are made up of similar small units.

Question 3.
Give few examples of synthetic fibres.
Answer:
Rayon, Nylon, Polyester, Plastic, Acrylic, Terylene etc. are synthetic fibres.

Question 4.
Give uses of Rayon and Nylon.
Answer:
Rayon is used to make clothes, bedsheets and carpets.
Nylon is used to make clothes, socks, ropes, tents, tooth brushes, belts, sleeping bags, curtains, parachutes etc.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 5.
List the characteristics of synthetic fibres which make them popular dress material.
Answer:
Characteristics of Synthetic Fibres:
Synthetic fibres possess the following unique characteristics:

  1. They are durable.
  2. They are less expensive.
  3. They dry up quickly.
  4. They are readily available.
  5. They are easy to maintain.
  6. It is easy to wash and does not wrinkle.
    These characteristics make them popular dress material.

Question 6.
What happens when different synthetic fibres like Nylon, Polyester and Acrylic burn in air ?
Answer:
On burning the different fabrics, the following results are obtained :

1. Nylon Burns with difficulty, fabric shrinks from flame, forming hard beads, smells of burning hair.
2. Polyester Same as nylon, produces a black smoke on burning.
3. Acrylic Shrinks from flame forming a black bead and a sooty flame.

Question 7.
Why plastic material like polythene is preferred over natural materials ?
Answer:
Advantages of Plastic material over Natural Material. Following are some advantages of plastic material (polythene etc.) over natural materials:

  1. It is cheaper and can be made on a large scale.
  2. It is light weight and can be easily transported.
  3. It is unbreakable, corrosion free, tough and flexible.
  4. It can be easily moulded.

Question 8.
Give uses of polythene.
Answer:
Uses of Polythene.
Polythene sheets are used for packing, satchels are used for packaging milk, polythene containers and pipes are used for storing and transporting water, oil and other materials. Polythene is also used as a water-proofing material.

Question 9.
Give some uses of PVC.
Answer:
Uses of PVC. PVC is used to make bottles, floor coverings, rain coats, soles of shoes, sandals and leather like materials.

Question 10.
What is blended fabric ? Why is it more comfortable to wear them than fabrics from pure synthetic fibres ?
Answer:
Blended Fabric (Polycot and Polywool).
It is a mixture of synthetic (man-made) and natural fibres such as terrycot (polyester and cotton fibres), terrywool etc. Pure synthetic fibres do not absorb sweat so well, so they stick to the body in hot weather. Some synthetic fibres catch fire very easily. To overcome this defect, synthetic fibres are mixed with natural fibres to make blended fabrics.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 11.
What are biodegradable and non-biodegradable substances ?
Answer:
Biodegradable Substances.
Substances which are decomposed by microbes (bacteria) are known as biodegradable substances. Bodies of dead animals, human excreta and many other substances are decomposed into simpler compounds or elements by bacteria. Such substances are biodegradable substances.

Non-biodegradable substancs.
Those substances which are not decomposed into simpler compounds by naturalprocessesor or bacteria are known as non-biodegradable substances.

Question 12.
What are natural and synthetic polymers ?
Answer:
1. Natural Polymers. The polymers which occur in nature and are obtained from plants and animals e.g. rubber, starch, cellulose, proteins etc. are called natural polymers.

2. Synthetic Polymers. The polymers which do not occur in nature and have been synthesised in laboratory are called synthetic polymers. These are also called manmade polymers e.g. polythene, poly-vinyl chloride, teflon, bakelite etc.

Question 13.
Suggest some ways to reduce the use of plastic materials.
Answer:
Plastic is non-biodegradable and is therefore, not environment friendly. The best way to reduce its use is to follow the 4R principle, which is as follows:

  1. Reduce – use less
  2. Reuse – use again
  3. Recycle – cycle again
  4. Recover – get again

Question 14.
Which way the plastic/polythene bags and wrappers thrown carelessly be harmful to animals ?
Answer:
The plastic/polythene bags and wrappers thrown carelessly after use are swallowed by stray animals. These plastic made materials are non-biodegradable either choke the respiratory canal of the animals or forms a lining in their stomach resulting in the cause of their death.

Question 15.
In which ways excessive use of plastic materials is harmful for environment and society ?
Answer:
Plastic is harmful for environment and the man in the following ways:

  1. Since Plastic is synthesised from petrochemicals so its excessive use would lead to exhaustion of non-renewable petrochemical the reserve of which is limited.
  2. Plastic is non-biodegradable and clogs the drains and sewage system if thrown carelessly after use which usually happens.
  3. Plastic does not burn completely and releases lots of poisonous fumes in the atmosphere causing air pollution.
  4. Sometimes carelessly thrown plastic/polybag are swallowed by animals resulting in their death.

Question 16.
Why it is not advised to wear polyester clothes while working in a kitchen ?
Answer:
Polyester is a synthetic fibre. It easily catches fire and melts so that it sticks to the body causing harmful and painful burns. That is why women are advised not to wear polyester clothes while working in kitchen.

Question 17.
As a sensible and responsible citizen what measures would you adopt in your individual capacity to keep public places free from plastic ?
Answer:

  1. I would not throw plastic carry bags in water bodies and on the road after use.
  2. While going to market for shopping I would take cotton or jute bag with me or I would insist on the shopkeeper to give me paper bag.
  3. I would use steel lunch box instead of one made from plastic.

PSEB 8th Class Science Solutions Chapter 3 Synthetic Fibres and Plastics

Question 18.
Four students planned to climb the top of mountain. They have selected the rope according to the table shown below. Which student has selected the correct rope and why ?

Name of the Students Rope
Inderjeet Cotton
Gopal Silk
Saloni Nylon
Karamjit Wool

Answer:
Saloni has choosen the correct rope because the rope of nylon is stronger than silk and wool.

Long Answer Type Questions

Question 1.
Give uses of the following:
(a) Polyester fibres
(b) Teflon
(c) Polythene
(d) Polypropylene
Answer:
(a) Uses of Polyester Fibres:

  1. Polyester fibres are used in textile industry for making a variety of clothes, such as sarees, dress materials, curtain clothes, etc.
  2. Polyester fibres mixed with natural fibres are used for making blended textiles such as terrycot (mixed with cotton), terry wool (mixed with wool).
  3. It is used for making sails of sail boats.
  4. It is used for making water hoses for fire fighting operations.

(b) Uses of Teflon:

  1. It is used for coating inside of non-stick cooking utensils.
  2. It is used in the manufacture of seals and gaskets.

(c) Uses of Polythene:

  1. It is used in the manufacture of bags, toys and pipes.
  2. It is used for covering electric cables because it is a good electrical insulator.

(d) Uses of Polypropylene:

  1. It is used to prepare seat covers.
  2. It is used for making ropes, fishing nets etc.

Question 2.
State four important properties and uses of nylon fibres.
Answer:
Properties of Nylon Fibres:

  1. Nylon fibres are very strong.
  2. Nylon fibres absorb very less water. Therefore, these can be dried rapidly.
  3. Nylon is wrinkle resistant and keep permanent creases.
  4. Nylon fibres have high wear and tear resistance and therefore, have longer life.

Use of Nylon:

  1. Nylon is used for a large number of purposes where high strength fibres are required.
  2. Nylon is used for making parachute fabrics, fishing nets, tyrecord, ropes, stockings (socks) and other textiles.
  3. Nylon is mixed with wool to make long-lasting fabrics.

Question 3.
Give the properties common to Nylon and Polyester fibres.
Answer:
Properties of Nylon and Polyester Fibres:

  1. Nylon and polyester fibres are very strong threads in comparison to silk, cotton, and wool.
  2. Both the threads have excellent resistance to wrinkles.
  3. Both the threads absorb very little water, so they dry out quickly.
  4. They have the high abrasion resistance and are not attacked by moths.
  5. Ordinary chemicals have no effect on them.
  6. They are lightweight and fine in texture.
  7. They are insoluble in common solvents.

Question 4.
What is plastic? What are its different types? Give properties of plastics which render them as a material of choice. Also, give its uses.
Answer:
Plastic. It is a polymer like synthetic fibre.
Example. Polythene

Types of Plastic. All plastics do not have the same arrangement of units. There are two types of plastics: One has a linear arrangement of units and the other has a cross-linked arrangement of units.

Properties of Plastics:

  1. Plastic is not attacked by air and water. That is they are non-reactive and non¬corrosive.
  2. Plastic is light, strong, and durable.
  3. Some plastics can be easily deformed on heating and some others do not soften on heating.
  4. Plastics are poor conductors of heat and electricity.

Uses of Plastics:

  1. In Health Care Industry. Plastics find extensive use in the Health care industry for packaging tablets, threads used for stitching wounds syringes, doctor’s gloves, and many other instruments.
  2. In Kitchen Cookwares. Plastic is used for making special cookwares to be used in micro-ovens which can withstand high temperatures.
  3. In making non-stick cookwares on which Teflon, a kind of plastic is used, oil and water do not stick.
  4. Fire Proof Plastics. Melamine plastic is used for coating the uniforms of firemen. This makes the uniform flame resistant.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Punjab State Board PSEB 8th Class Social Science Book Solutions Geography Chapter 2 Natural Resources Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Social Science Geography Chapter 2 Natural Resources

SST Guide for Class 8 PSEB Natural Resources Textbook Questions and Answers

I. Answer the following questions in 1-15 words:

Question 1.
Into which relief features can the land be divided?
Answer:
Mountains, plateaus, and plains.

Question 2.
What is the importance of plains?
Answer:
Plains support agriculture and dense population. These meet human needs. Plains are suitable for the development of vegetation and crops.

Question 3.
What are the factors that affect the formation of soils?
Answer:
Parent rocks, climate, plants and animals.

Question 4.
How many types of soils are found in India? Write the names of these types.
Answer:

  • Alluvial soils
  • Black soils
  • Red soils
  • Laterite soils
  • Forest and Mountain soils
  • Desert soils.

Question 5.
What type of crops can be grown on Black soil?
Answer:
Cotton, wheat, jowar, flax, tobacco, sun flower, crops are grown in Black soils. Rice and sugarcane are grown with the help of irrigation.

Question 6.
Write the names of main sources of water.
Answer:

  1. Rainfall
  2. Rivers and streams
  3. Canals
  4. Tanks
  5. Groundwater.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 7.
What is given by the natural vegetation to man?
Answer:

  1. Timber (wood) which is used for buildings.
  2. Fruit, medicines and other products.

Question 8.
Name the types of forests found in India.
Answer:

  1. Evergreen forests
  2. Deciduous forests
  3. Desert forests
  4. Mountain forests
  5. Delta forests.

Question 9.
What are migratory birds and where do they come from?
Answer:
In cold season birds migrate to India. These are called migratory birds. These come from Mosay Siberia and China.

II. Answer the following questions in 50-60 words :

Question 1.
Write about the land use in India.
Answer:
Land use pattern. India has a total geographical area of 32.8 crore hectares. Main characteristics of land use are given below:

  1. Net Sown Area. About 46% of total land (77 crore hectares) is net sown area. This vast area shows the importance of agriculture in India as crops are grown in it
  2. Fallow land. About 8% land (2.2 crore hectares) is left as fallow land and is cultivated after two or three years.
  3. Forests. About 22.2% of land is (6.6 crore hectares) under forests. It should be 33%. Afforestation be done and’ deforestation be banned.
  4. Plantation crops. About 1% land is under plantation crops like tea, coffee, etc.
  5. Other uses. Land under permanent grassland, cultivable waste and not available for cultivation amounts to about 5 crore hectares.
  6. Area under forests is increasing. Fallow land has been reduced in area. Net sown area under doubled cropped area is also increasing.

Question 2.
After mentioning the types of soil write the importance of alluvial soil.
Answer:
There are six types of soils in India :

  1. Alluvial soils
  2. Black soils
  3. Red soils
  4. Laterite soils
  5. Forest and Mountain soils
  6. Desert soils.

Alluvial Soils: These are made up of fine particles. These are clay soils and fertile soils. Therefore, the alluvial plains are very useful for agriculture. For example, the Indus- Ganga-Brahmputra plain of India. It has two types-Khadar and Bangar soils.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 3.
How is the soil resource being conserved?
Answer:
Soil Conservation. Soil is a very fundamental natural resource. Soil formation is a slow process, but it is easily lost by soil erosion. Sound farming practices and measures be adopted to conserve, protect, renew and maintain soil fertility.

These methods constitute soil conservation.

  • Afforestation: Afforestation and reforestation is needed to hold the soil.
  • Controlled grazing: The number of cattle to be grazed on slopes should be according to the carrying capacity of the pastures.
  • Terraced agriculture: Slopes must be cut into a series of terraces (fields) for cultivation so as to slow down the flow of rain water.
  • River dams: River dams are built in the upper course of rivers to control floods and check soil erosion.
  • Crop rotation: Crop rotation system be applied and the land should be allowed fallow for some time. Soil fertility can be maintained in this way.

Question 4.
Give the importance of rivers and canals.
Answer:
India has a total of 1869 billion cubic metre water resources. Out of this, only 660 billion cubic metres have been utilized for irrigation. India needs to plan these water resources to be utilized for agriculture. For this more multipurpose projects should be planned and completed. Ground water resource should be used for providing water power to tubewells. A lot has been done to manage our water resources, but due to technological and financial limitations, still much of water goes waste to oceans.

Question 5.
How the water can be conserved?
Answer:
Water is a vital resource for the development of economic activities. Water should be conserved in the following ways. Waters of ocean, river and lakes should not be polluted. It should he saved from urban waste and chemicals of industries. It should be recycled to use it again. Dams should be built across the rivers and lakes to store water in reservoirs.

Question 6.
Write a note on Deciduous forests.
Answer:
Deciduous forests shed their leaves in a specific season. In spring season, these leaves become green.’These are the most widespread forests in India. These are economically very important from the point of getting timber. These include Sal, Teak, Bamboo, Shisham and Khair trees.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 7.
What steps have been taken by Govt, of India for protection and conservation of wildlife? (P.S.E.B. 2020)
Answer:
Wildlife plays an important role in the human progress and civilisation. The primitive man had to depend on animals for food and other basic needs. Later on, man began to domesticate animals. Still hunting is carried on in many parts of the world. Many useful and valuable species are becoming extinct due to hunting or killing of animals. Man has upset the ecological balance by killing of birds and animals.

Many steps have been taken for the preservation of wildlife.

  • Parks and sanctuaries have been established in hilly areas and forests.
  • Hunting of some rare species of animals has been banned.
  • Public attention is focused on making efforts for the preservation of wildlife.
  • Wild animals like lion, tiger, deer, etc. are protected during closed season when they cannot be hunted.

III. Answer the following questions in about 125-130 words :

Question 1.
What are Natural Resources? Write down the types and importance of soils and natural vegetation.
Answer:
Natural Resources are free gifts provided by nature. These include land, water, soil, forests, wildlife, minerals, etc.
1. Soils: The main types of soils are :

  • Alluvial soils
  • Black soils
  • Red soils
  • Laterite soils
  • Forests and Mountain soils
  • Desert soils.

Importance: Soil is a valuable resource. It is required for cultivation of crops. Fertile soil is the basis of developed agriculture. It becomes more important for a country like India which is an agricultural country. Many types of soils are found in India and many types of crops are grown on it.

2. Vegetation: The following types of vegetation is found in India :

  • Evergreen forests
  • Deciduous forests
  • Desert forests
  • Mountain forests .
  • Delta forests.

Importance of Forests: Forests are a valuable resource like a river system, it is a multiple resource. Forests provide mankind with a number of products. Forests have greatly influenced human activities. Modem civilization depends more and more on forests.

Following are the direct and indirect advantages of forests :

  • Forests provide many things to meet our food requirements like wild fruits, nuts, berries, etc. Many tribes are dependent on gathering of these products in forests.
  • Forests are a source of timber for house-building, furniture-making, ship-building, etc.
  • Forests supply about 40% of fuel of the world. Wood has been the major source of fuel in house smelting industries and running locomotives.
  • Soft wood trees supply raw materials, wood pulp, paper, rayon industries.
  • Many products like rubber, pitch, gum, tanning materials, cork, camphor, fir, herbs, etc. are gathered from forests.
  • Forests provide plywood and fibre wood for packing purposes

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 2.
How the water and wildlife can be conserved? Express your views.
Answer:
India is rich in fauna and flora. There is a great biological diversity in, India. There are about 90000 known species of animals. It has 2500 species of fish and 1200 species of birds. But many of these fauna have been destroyed by-man. Many rare species have become extinct in India. Our rich wildlife is rich heritage formed through centuries. It must be preserved. Many of the fauna are found only in India such as swamp deer, the one-horned rhinoceros, the bison, Kashmir stag, Nilgai, etc. These rare species are in danger of extinction.

The following measures have been taken for conserving and protecting wildlife as well as its bio diversity in the country. Wildlife is a gift of nature and a thing of beauty. Wildlife Act provides for the protection and conservation of these species.

For this purpose :

  • A network of 89 national parks, 490 sanctuaries and 13 biosphere reserves have been established.
  • Under Project Tiger 27 Tiger Projects in 14 states have been set up.
  • 15 mangroves have already been identified for intensive conservation and management purpose.

Conservation and Management of Water Resources
1. Watershed Management. The management of the divide between two drainage basin called watershed is taken as a physiographic unit. The inter-basin management of water helps to divert water from surplus areas to scarcity areas. It also helps replenish ground water resources. It involves integrated development of two or diverse basins and saves on technical and financial resources.

2. Rainwater Harvesting. Rainwater is stored in roof top tanks, on ground Or underground tanks or check dams, percolation pits, etc. during rainy season and then it is used for irrigation, improving vegetation cover in dry season. While it increases productivity it also replenishes ground water resources.

IV. Map Skill

Question 1.
Show the following on the outline map of India :
1. Northern plains of India
2. Ganga and Brahmputra Rivers
3. Region of Alluvial soils
4. A state with black soil
5. An area of evergreen forests
6. A region with mountain and delta vegetation.
Answer:
PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources 1

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

V. Activity

Question 1.
Show eight types of soils on the map of India.
Answer:
PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources 2

PSEB 8th Class Social Science Guide Natural Resources Important Questions and Answers

Multiple Choice Questions :

Question 1.
Which one of the following is not a type of forest found in India?
(a) Evergreen forest
(b) Tidal forest
(c) Deciduous forest
(d) Desert forest.
Answer:
(b) Tidal forest.

Question 2.
Cutting down of trees is called :
(a) Afforestation
(b) Deforestation
(c) Slash and Burn
(d) Strip cropping
Answer:
(b) Deforestation.

Question 3.
Sunderbans is the habitat of :
(a) Tiger
(b) Lions
(c) Elephants
(d) Camels
Answer:
(a) Tiger.

Question 4.
Which is the oldest landmass of India?
(a) Northern Plain
(b) Peninsular Plateau
(c) Himalayas
(d) Aravallis.
Answer:
(b) Peninsular Plateau.

Question 5.
Natural vegetation and wildlife is found in :
(a) Biosphere
(b) Hydrosphere
(c) Atmosphere
(d) None of the above.
Answer:
(a) Biosphere.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 6.
Following picture shows a specific type of forests, names these forests.
PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources 3
(a) Evergreen forests
(b) Tidal forests
(c) Deciduous forests
(d) Deserts
Answer:
(a) Evergreen forests.

Question 7.
Study the following picture and give the answer what this picture is explained?
PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources 4
(a) Afforestation
(b) Deforestation
(c) Slash and Burn
(d) Strip Gopping
Answer:
(b) Deforestation.

Question 8.
Jhoolan Devi does the agricultural work with her family but her family is forced to migrate to other place to do agriculture due to reduction in soil fertility. What type of farming does this situation represent?
(a) Permanent agriculture
(b) Horticulture.
(c) Intensive agriculture
(d) Jhum cultivation.
Answer:
(d) Jhum cultivation.

Question 9.
How much part of total area of India is under forests? (P.S.E.B. 2020)
(a) 11.9%
(b) 52.2%
(c) 22.2%
(d) 32.2%.
Answer:
(c) 22.2%

Fill in the Blanks :

Question 1.
In India soils are of types.
Answer:
six

Question 2.
__________ is the upper most layer of the earth crust .
Answer:
soil

Question 3.
Land use depends on __________ factor.
Answer:
physical

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 4.
Ice-sheets are found in __________
Answer:
greenland

Question 5.
About ________% of the total surface area of the earth is under water.
Answer:
71

True/False :

Question 1.
The original rock called Parent Rock.
Answer:
True

Question 2.
Pollution means contamination of natural resources.
Answer:
True

Question 3.
A dripping tap wastes 100 litres in a year.
Answer:
False

Question 4.
An average urban Indian uses about 35 litres of water everyday.
Answer:
False

Question 5.
Land suitable for agriculture is called Arabic land.
Answer:
True.

Very Short Answer Type Questions

Question 1.
Describe the distribution of Land and Water on earth.
Answer:
29%-Land and 71%-Water.

Question 2.
Why is there need for Afforestation in India?
Answer:
There should be at least 33% area under forests in India. But only 22.2% area is under forests in India. So there is need for growing trees on large scale.

Question 3.
What do you mean by culturable waste?
Answer:
Some land is culturable, but it is not cultivated due to some reasons. Such as scarcity of water, soil erosion, waterlogging, etc.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 4.
In which areas forest and mountain soils are found? State any two characteristics.
Answer:
These soils are found along forests and hill slopes.

Characteristics:

  • These have organic elements.
  • These lack in Potash, Phosphorus, Lime. Therefore, use of fertilizer is essential.

Question 5.
What are alluvial soils?
Answer:
Alluvial soils are formed by deposition of fine sediments. These sediments are brought by the river. Sea waves also deposit these along coasts. Alluvial soils are very fertile.

Question 6.
Why is black soil called cotton soils? Name one other name of it.
Answer:
Black soil is suitable for the cultivation of cotton. So it is called cotton soil. It is also called Regur soil.

Question 7.
Where are desert soils found in India?
Answer:
Desert soils are found in Rajasthan, Punjab, Haryana and in some parts of Gujarat.

Question 8.
Why is earth called a ‘watery planet’?
Answer:
Most of the earth (71%) is covered with water. So it is called watery planet due to excess of water.

Question 9.
In which form most of water is found on earth? How much per cent is it of total water?
Answer:
Most of water is found in the form of oceans, seas and salt lakes. It contains 97.20% of total water.

Question 10.
For which purpose, most of water is used and how much?
Answer:
93.37% of total water is used for agricultural purposes.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 11.
Where are Tanks found?
Answer:
Tanks are found in areas where there are no perennial rivers and canals. Ground water is very deep. In India most of tanks are found in southern India.

Question 12.
Write briefly about desert vegetation.
Answer:
Desert vegetation is found in arid areas. The vegetation is scanty. It includes Date palm, Cactus and Thorny bush. In India, this type of vegetation is found in Rajasthan, Gujarat and Haryana.

Question 13.
Name four trees of mountain vegetation.
Answer:

  1. Fir
  2. Deodar
  3. Oak
  4. Nuts.

Question 14.
What is terrace farming?
Answer:
Terrace farming. The growing of crops on level steps or terraces that have been constructed on hillsides.

Question 15.
What is a wildlife sanctuary?
Answer:
A wildlife sanctuary is dedicated to protect wildlife and conserve forests.

Question 16.
What are Protected forests?
Answer:
There are forests reserved for timber but grazing is allowed subject to minor restrictions. These are 29.2% of total forests.

Question 17.
What is contour ploughing?
Answer:
Contour Ploughing: Technique of ploughing parallel to the contours of a hill slope rather than up and down the slope, so as to reduce soil erosion.

Question 18.
What is strip cropping?
Answer:
Strip Cropping. Growing of different crops on parallel narrow strips of ground, usually following the contour patterns.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 19.
What is a shelterbelt?
Answer:
Shelter belt: In dry regions, rows of trees are planted to check the wind movement for protecting soil cover.

Short Answer Type Questions

Question 1.
Write a note on alluvial soils. Classify these into two groups.
Answer:
Alluvial soils. These cover 45% land of India :

  1. Alluvial soil is deposited by rivers.
  2. These soils are limited to river basins and plains.
  3. These are very fertile soils.
  4. These consist of fine-grained. clay and sand.
  5. These soils are rich in potash, but poor in phosphorus.
  6. These are usually deep soils.

Types:
(a) Khadar soils
(b) Bangar soils.

(a) Khadar soils are new alluvial soils while
(b) Bangar soils are old alluvial soils.

Question 2.
State the characteristics of Black soils. Describe its distribution in India.
Answer:
Black Soils. Black soils are mainly found over the Deccan Lava tract (Deccan trap) including Maharashtra, Madhya Pradesh, Gujarat and Andhra Pradesh. These soils are found in river valleys of Narmada, Tapti, Godavari and Krishna. These soils have

been formed due to weathering of lava rocks. These soils cover an area of about 5 lakh sq. km. These soils are rich in lime, iron, magnesia and alumina. But these lack in phosphorus, nitrogen and organic matter. These are also called ‘Regur Soils’. These soils are most suitable for cotton cultivation and are known as ‘Black Cotton Soils’. These soils are compared with Chernozem soils of Russia and Prairies soils of U.S.A. These soils can hold water. These soils are suitable for rice, wheat, jawar, sugarcane, tobacco and oilseeds.

Question 3.
Write a note on desert soils.
Answer:
Desert Soils. These soils cover 2 lakh sq. km. area in dry areas of Rajasthan, Gujarat, Punjab, Haryana. These coarse soils are suitable for the cultivation of jawar, bajra, cotton, oats, maize, pulses etc. Methods of irrigation are used. These are sandy soils and are infertile. These do not hold water. So these are used for dry crops. In India 4.3% area is covered by desert soils.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 4.
State the characteristics and distribution of Red Soils in India.
Answer:
Red Soils: These soils are found in Chotta Nagpur plateau, Telangana, Nilgiris, Tamil Nadu, Karnataka, Andhra Pradesh and areas on periphery of Deccan Plateau. These soils have been formed due to decomposition of underlying igneous rocks under heavy rainfall. These soils have different shades of red and yellow. The red colour of these soils is due to oxidation and diffusion of iron in hard crystalline rocks. These are used for the cultivation of millets, pulses, linseed, tobacco, etc. These soils cover the largest area (10.6%) in Peninsular India, particularly S.E. part of the Peninsula. These soils are poor in lime, nitrogen and humus. Fertilizers are added to make these fertile.
PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources 5

Question 5.
What are the characteristics of laterite soils? Describe its distribution in India.
Answer:

  • The laterite soils are of brick colour.
  • These are shallow, acidic and less fertile.
  • These are less fertile due to leaching of soil.
  • These are poor in nitrogen, potash but very rich in iron.
  • These are found in Tamil Nadu, Western Ghats, Rajmahal hills, Vindhyas, Satpuras and Malwa plateau. These soils cover 7.5% area of the country
  • Some areas of Maharashtra, Andhra Pradesh, Orissa, Karnataka, Jharkhand also have laterite soils.
  • These are suitable for cultivation of Rubber, Tea, Coffee and Coconut.

Question 6.
What do you mean by wildlife? Describe in brief the wildlife of India.
Answer:
Like diverse flora, our fauna is found to be equally rich and varied. There are about 80,000 known species. The country in its fresh and marine waters has as many as 2500 species of fish. Likewise there are about 1200 species of birds. In addition there are amphibians, reptiles, mammals and small insects and worms. Migratory birds also come to India during winter

Mammals: Among the mammals, the elephant is the stately animal. It is a typical animal of hot wet equatorial forests. It is found in the jungles of Assam, Kerala and Karnataka. In these areas, it rains heavily and the forests are very dense. On the other hand camels and wild asses are found in hot deserts. Camels are found in Thar desert.

Question 7.
Why is the Land considered an important resource?
Answer:
Land is considered as an important resource because:

  1. It is used for different purposes like agriculture, forests, pastures.
  2. Human beings make their houses and live on it and also it provides most of the products they need; like food, wood etc.

Question 8.
Name the five factors controlling soil formation.
Answer:
The five factors controlling soil formation are:

  1. Nature of the parent rock
  2. Topography
  3. Climate
  4. Time
  5. Organism in it.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 9.
Write any two reasons for land degradation today.
Answer:
There are many factors which lead to the degradation of land. Both nature and human factors can lead to degradation of land.

  1. Growing population and their ever growing demand is the main reason of land degradation today.
  2. Deforestation is the another main reason of land degradation.

Question 10.
Why is land considered an important resource?
Answer:
Land is considered as an important resource because :

  1. It is used for different purposes such as agriculture, forest, mining, pastures, etc.
  2. Human beings make their houses and five on it and also it provides most of products they need like food, wood, etc.
  3. Human beings set up their industries, build roads and run other commercial activities.

Question 11.
What factors control the utilization of land?
Answer:
The physical and human factors control the utilization of land. These include :

  1. relief of features,
  2. climatic conditions,
  3. soils,
  4. density of population,
  5. technical level of the people,
  6. land tenure,
  7. duration of the occupation of the area etc.

The interplay of physical and human factors has developed many types of land uses.

Question 12.
What is terrace farming?
Answer:
Terrace farming: The growing of crops on level steps or terraces that have been constructed on hillsides.

Question 13.
What is a wildlife sanctuary?
Answer:
A wildlife sanctuary is dedicated to protect wildlife and conserve forests.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 14.
What are the effects of deforestation?
Answer:
The effects of deforestation are as under :

  • It affects the ecosystem.
  • It increases soil erosion.
  • It affects underground flow of water.
  • Disappearance of wildlife as well as variety of plants.
  • Leads to serious deterioration of genetic reserves.

Question 15.
What are Protected forests?
Answer:
These are also forests reserved for timber but grazing is allowed subject to minor restrictions. These are 29.2% of total forests.

Question 16.
What is contour ploughing?
Answer:
Contour ploughing: Technique of ploughing parallel to the contours of a hill slope rather than up and down the slope, so as to reduce soil erosion.

Question 17.
What is strip cropping?
Answer:
Strip Cropping. Growing of different crops on parallel narrow strips of ground, usually following the contour patterns.

Question 18.
For what purposes land is used? What is land use pattern?
Answer:
Land is used for different purposes.

They are :

  • Cultivation of crops agriculture.
  • Grazing of animals.
  • Building houses and roads.
  • Mining.
  • Industries.

These uses of land is commonly termed as land use pattern.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 19.
What is a shelterbelt?
Answer:
Shelterbelt: In dry regions, rows of trees are planted to check the wind movement for protecting soil cover.

Question 20.
Write the importance of forests.
Answer:
Importance of forests. Forests play an important role in human life. They provide food, wood and timber to us. Many medicinal plants are found in the forests. They also help in maintaining ecological balance and checking soil erosion. They play an important role in the economy of our country.

Question 21.
What is the role of insects in soil formation?
Answer:
Insects play a very important role in soil formation. Without worms and insects, the work of soil formation will be incomplete. They do it through both physical or mechanical means and speeding up chemical reactions.

Question 22.
Why does soil lose fertility?.
Answer:
The soil loses its fertility when continuously used. When crops are grown every year it loses its nutrients which are necessary for good soil.

Question 23.
What are the factors that control soil formation?
Answer:
Soil formation is controlled by five factors. These are :

  1. Nature of parent rock
  2. The topography
  3. The climate
  4. The organism in the soil
  5. Time.

Question 24.
What is the importance of landforms?
Answer:
Man’s economic activities differ with different landforms.

  1. Mountainous regions are not much suitable for human settlements.
  2. Dense population is found in plains.

Question 25.
‘Land plays a fundamental role.’ Discuss.
Answer:
Plains are known for agriculture and dense population. Plains, 43% area of India, fulfill man’s many needs. The agriculture depends upon plain.

Question 26.
What is fallow land?
Answer:
The land which is not used for agriculture for 1 to 5 years is left vacant. It restores the fertility of the soil. It is called fallow land.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 27.
Examine the importance of water.
Answer:
Water is a valuable and important resource. It is the basis of life on earth. Water fulfils many human requirements. It is used for drinking, bathing, washing and agriculture.

Question 28.
Name the major threats to be environment.
Answer:
Land degradation, landslides, soil erosion and desertification are the major threats to the environment. This is because of expansion of agriculture and construction activities.

Question 29.
Write the steps that can help in conserving degraded land.
Answer:
The following steps may help in conservation and reclamation of degraded land:

  1. Afforestation and control on overgrazing.
  2. Plantation of land reclamation of plants.
  3. Regulated use of chemical pesticides and fertilisers.
  4. Proper discharge of sewage industrial effluents.
  5. Maintain proper mining processes and technique.

Fill in the blanks :

Question 1.
Nearly 97% of the earth’s total water is in the form of __________ and __________
Answer:
Sea, oceans

Question 2.
Tiger park at Dudhwa is situated in the state __________
Answer:
Uttar Pradesh

Question 3.
__________ is produced with the help of running and falling water.
Answer:
Hydro-electricity

Question 4.
Polar areas are populated areas.
Answer:
sparsely

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 5.
We can __________ the supply of drinking water by installing desalination plants.
Answer:
increase

Question 6.
In __________ areas landslides have been a major and widely spread natural disaster.
Answer:
mountains.

Long Answer Type Questions

Question 1.
What are the sources of fresh water in India? Describe each.
Answer:
Two types of water is found on earth-saline and fresh. Man uses freshwater for different purposes. Its sources are :
1. Rainfall. Rainfall is the major source of water on the earth. Some water is evaporated, some water flows down to the oceans and some water goes underground through percolation. India has average annual rainfall of 118 cm.
Rain water or running water flowing on the surface of land is called surface water. It includes water in oceans, seas, lakes, rivers, etc. India’s total surface water resources are 1869 billion cubic metres.

2. Ground Water. Rain water that goes beneath the surface of the earth by percolation is called ground water. India has a total ground water resources of 40 million hectare metres. This water can be obtained by digging wells. Sometimes it comes out through springs also.

3. Rivers and Canals. From early periods, rivers and canals have been very important. Many civilisations developed along river banks. Man built dams on rivers to use water for irrigation through canals.

4. Tanks. Tanks are found in areas deficit in rainfall. The water level is very deep so it is difficult to use it. Rain water is collected in depressions called tanks. Tanks are mostly found in southern India.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 2.
What do you mean by Natural Vegetation? On what factors does it depend? Describe the different types of forests found in India.
Answer:
Natural vegetation includes plants and trees which grow automatically according to climate. It depends upon climate, soil, drainage, temperature, rainfall and altitude.

We can divide India into the following vegetation belts :

  • The Tropical Rain Forests.
  • The Tropical deciduous or the Monsoon forests.
  • The Thorn Forests.
  • The Tidal Forests.
  • Mountain Forests.

1. The Tropical Rain Forests are of two varieties: evergreen and semi-evergreen. Regions having more than 300 centimetres of rainfall have evergreen forests. The hills of Assam and the rainy slopes of the Western Ghats are such areas. The region where the rainfall is between 200 and 300 centimetres have semi-evergreen forests. Such areas are there in Assam, West Bengal, Orissa and in Western Ghats.

2. The Tropical Deciduous or Monsoon Forests are found in the regions where rainfall is between 100 and 200 centimetres. Teak and sal are the most important trees of monsoon forests besides sheesham, mahua, bamboo, etc. The belt of monsoon forests extends from the Western Ghats in the south to the Shiwalik hills in the north.

3. The Thorn Forests are found in Rajasthan, Haryana, Punjab, Gujarat, dry parts of Madhya Pradesh and the Deccan, where the rainfall is less than 80 centimetres. Kikar, Babool and Wild Palm are the common trees of this type of forests.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources 6

4. The Tidal Forests are mainly found along the river deltas. Mangrove and Sundri trees are the common trees found in the Ganga delta in Bengal which is also “called the Sundarban.

5. The Mountainous Forests. The foothills of the Himalayas are covered with tropical deciduous forests. At high slopes, oak, chestnuts, chir, pine trees of sub-tropical type are formed. At a height of 3300 metres, coniferous forests like blue pines, cedars silver firs, deodars are found. Alpine pastures are found at high altitudes.

Question 3.
Write a short note on conservation of soils.
Answer:
Soil Conservation. Soil is a fundamental natural resource. Soil formation is a slow process, but it is easily lost by soil erosion. In fact, more soil is being lost each year than nature makes. Soil erosion must be checked. Sound farming practices and measures be adopted to conserve, protect, renew and maintain soil fertility.

These methods constitute soil conservation.
1. Afforestation: In some areas, the original vegetation cover has been removed such as in Shiwalik hills. In such areas afforestation and reforestation is needed to hold the soil. Advance of deserts can be checked by planting trees along the margins of deserts.

2. Controlled grazing: The number of cattle to be grazed on slopes should be according to the carrying capacity of the pastures.

3. Terraced agriculture: Slopes must be cut into a series of terraces (fields) for the cultivation so as to slow down the flow of rain water.

4. Contour Ploughing: It is done to check soil wash on slopes. Ploughing is done at right angles to the hill slopes.

5. Crop rotation: Crop rotation system be applied and the land should be allowed fallow for some time. Soil fertility can be maintained in this way.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 4.
Distinguish between Evergreen Forests and Deciduous Forests.
Answer:

Evergreen Forests Deciduous Forests
1. Evergreen forests are found in regions that experience tropical climate throughout the year. 1. Deciduous forests are found in regions that experience rainy and dry season.
2. They do not shed their leaves in any season of the year. 2. They shed their leaves once a year.
3. Their height exceeds 60 metres. 3. They are less than 50 metres in height.
4. They have less economic importance as the wood from them is very hard and is of not much use. 4. They have more economic value, as their wood is soft and durable.
5. Some trees are ; Rosewood, Mahogany etc. 5. Some trees are ; Teak, Sal, etc.

Question 5.

What is the most important feature of the Landuse pattern in India?
Answer:

  1. India has total geographical area of 828 million sq. km. (3280 lakh hectares). The land use data is available for about 93% of the total area. It shows that 151 million hectares (47%) is net sown area. Thus India has a very high percentage (47%) of total area under cultivation. No other big country has such a large area under cultivation.
  2. Another satisfying feature is that only 8% of land is fallow which is not cultivated so as to restore the fertility of the land. It is notable that fallow land has risen to 8% from earlier figure of 5%. It reflects that care for land resources has become essential.
  3. The area under pastures is also small (4%).
  4. The area under cultivable waste is 5%. This wasteland can be brought under cultivation to increase productivity.
  5. The forest cover is low, only 22%. It is desirable to have about one third of the total land area under forests to maintain a healthy environment.

Question 6.
Explain the factors controlling soil formation.
Answer:
Soil formation is controlled by five factors :

  1. nature of parent rock,
  2. the topography,
  3. the climate,
  4. the organism in the soil and
  5. time.

1. Parent Rock: The original rock called parent rock, from which the soil is formed, determines its basic characteristics. For example, shales contribute clays, while sandstones contribute sand grains.

2. Climate: Temperature and precipitation are the main climatic factors affecting soil formation. Frequent temperature changes and presence of water quicken soil formation through increased weathering.

3. Topography: Topography affects the drainage of an area. On a steep slope, there is hardly any chance of accumulation of weathered rocks. They are moved down the slope by water and under force of gravity. In plains and areas with gentle slope, soils are accumulated without any hindrance.

4. Organisms: Dead plants and animals provide humus to soil. Organisms like earthworms and ants through their movements create space for air and water in the soil.

5. Time: Time factor is also important because longer the time for soil formation, more deeper is the soil layer. Besides weathering of rocks, soil is also formed by deposition of materials by moving waters (rivers) and winds in low-lying areas. Alluvial soils of river valleys are very fertile and deep.

Question 7.
What are water resources? What are their uses?
Answer:
Water Resources. Water is a unique liquid because there is no alternative for it. It is essential for all forms of life. Compared to most other liquids, water has a high capacity to absorb or store heat.

Water is a major body constituent of several plant and animal species. Seventy percent of the human body consists of water. Humans use water for several purposes—domestic (drinking, cooking, washing, etc.), agricultural (irrigation), industrial and generation of electricity.

PSEB 8th Class Social Science Solutions Chapter 2 Natural Resources

Question 8.
How are vegetation and wildlife useful for us?
Answer:
Vegetation and wildlife are valuable resources
1. Plants provide us

  • Timber, fruits, nuts, latex, oil, gum, medicinal herbs, etc.
  • Shelter for animals and birds.
  • Protect soil and storage and water.
  • Oxygen to breathe.

2. Wildlife provides us

  • with milk, meat, hides, wool, honey.
  • helps as decomposers, act as scavengers.
  • maintain the ecological balance.
  • The birds feed on insects and act as decomposers as well.
  • Vulture each dead livestock and act as scavengers. They are considered as a vital cleaner of environment.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 6 Combustion and Flame Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 6 Combustion and Flame

PSEB 8th Class Science Guide Combustion and Flame Textbook Questions and Answers

Exercises

Question 1.
List conditions under which combustion can take place.
Answer:
Conditions necessary for combustion:

  1. Presence of a combustible substance.
  2. Presence of a supporter of combustion.
  3. Attainment of ignition temperature.

Question 2.
Fill in the blanks.
(a) Burning of wood and coal causes ……………… of air.
(b) A liquid fuel, used in homes is ………………
(c) Fuel must be heated to its …………………………………… before it starts burning.
(d) Fire produced by oil cannot be controlled by …………………..
Answer:
(a) Pollution.
(b) Kerosene.
(c) Ignition temperature.
(d) Water.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Question 3.
Explain how the use of CNG in automobiles has reduced pollution in our cities.
Answer:
CNG is a clean gaseous fuel. It burns completely in air and does not produce any harmful gases. So, the use of CNG in automobiles has reduced pollution in our cities.

Question 4.
Compare LPG and wood as fuels.
Answer:
LPG is a clean fuel. It is liquefied petroleum gas and is filled in cylinders. It burns with a blue flame and leaves no residue. Its calorific value is high. Wood is not a clean fuel. It burns and release lots of smoke and ashes are left behind. It give very low amount of heat.

Question 5.
Give reasons:
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
Answer:
(a) The substance used for extinguishing fires on electrical appliances or circuit should not be good conductor of electricity as there are chances of electrocution. So, water being a good conductor of electricity, is not used for extinguishing fires on electrical appliances or circuit. Carbon-tetrachloride (non-electrolyte) is used for this purpose.

(b) LPG is liquefied petroleum gas. It has high calorific value of 50 kJ/g. It is neat and clean fuel. It burns with a smokeless flame and does not produce poisonous gases. While wood has less calorific value of 17 kJ/g. It gives out smoke and poisonous gases on burning. So, LPG is better fuel than wood.

(c) When paper wrapped around an aluminium pipe is brought near a flame, it does not burn because the heat gets transferred to aluminium pipe and the ignition temperature of paper is not achieved.

Question 6.
Make a labelled diagram of a candle flame.
Answer:
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 1

Question 7.
Name the unit in which the calorific value of a fuel is expressed.
Answer:
Kilojoules per kilogram (kJ/kg).

Question 8.
Explain how CO2 is able to control fires.
Answer:
CO2 gas is heavier than air. So, it forms an envelope around the burning fire. This, cuts off the supply of oxygen gas and fire stops burning and gets under control.

Question 9.
It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.
Answer:
Green leaves have a high moisture content in them and in the heap of green leaves, oxygen present is very less. Whereas dry leaves have no moisture content and there is lot of oxygen available in this heap. So, it is difficult to burn a heap of green leaves than a heap of dry leaves.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Question 10.
Which zone of flame does a goldsmith use for melting gold and silver and why ?
Answer:
Goldsmith usually uses the upper most, non-luminous, blue flame for melting gold and silver because it is the hottest part of the flame.

Question 11.
In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.
Solution:
Mass of fuel = 4.5 kg
Heat produced = 180,000 kg
Now, Calorific value of a substance = \(=\frac{\text { Heat produced }}{\text { Mass }}\)
= \(\frac{180,000}{4 \cdot 5}\) kj/kg
= \(\frac{40,000}{1}\)
= 4 × 104 kj/kg

Question 12.
Can the process of rusting be called combustion ? Discuss.
Answer:
Rusting.
When iron is exposed to moist air, it gets coated with hydrated iron oxide. This process is called rusting and the coating formed is called rust. Chemically rust is hydrated form of ferric oxide, Fe2O3. xH2O. It is reddish brown in colour.
The overall reaction for rusting is:
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 2
Combustion is an oxidation reaction and rusting is also an oxidation reaction but very slow. So, rusting can be termed as slow combustion reaction.

Question 13.
Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time.
Answer:
Ramesh’s beaker will get heated in a shorter time because the outermost part of flame is the hottest part.

PSEB Solutions for Class 8 Science Combustion and Flame Important Questions and Answers

Multiple Choice Questions

Question 1.
With the help of the following diagram tell the colour of its flame?
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 3
Answer:
The colour of the flame of lamp: yellow
The colour of the flame of candle : yellow
The colour of the flame of bunsen burner : blue.

Question 2.
In the figure below various parts of candle flame are given. Tell which one of them is less hot ?
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 4
(а) Outer Zone
(б) Inner Zone
(c) Middle Zone
(d) None of these.
Answer:
(c) Middle Zone.

Question 3.
Fuel is:
(a) Solid
(b) Liquid
(e) Gas
(d) Solid, liquid and gas
Answer:
(d) Solid, liquid and gas

Question 4.
Which of the following gas is supporter in combustion?
(a) Oxygen gas
(b) L.P.G.
(e) Nitrogen gas
(d) Carbondioxide gas
Answer:
(a) Oxygen gas.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Question 5.
Which of the following is combustible substance ?
(a) Iron nail
(b) Glass
(c) Paper
(d) A piece of stone
Answer:
(c) Paper

Question 6.
The conditions for combustion are:
(a) Fuel and air
(b) Fuel, air and ignition temperature
(c) Fuel and ignition temperature
(d) Air and ignition temperature.
Answer:
(b) Fuel, air and ignition temperature.

Question 7.
Which out of the following has minimum ignition temperature ?
(a) Petrol
(b) Kerosene
(c) Coal
(d) L.P.G.
Answer:
(d) L.P.G.

Question 8.
Which of the following gas causes acid rain ?
(a) H2
(b) N2
(c) Carbon-monoxide
(d) Oxides of sulphur and nitrogen
Answer:
(d) Oxides of sulphur and nitrogen.

Question 9.
While extinguishing fire of electric wires and electric instruments, which of the following item is not used ?
(a) Sand
(b) Water
(c) Foam
(d) Carbondioxide
Answer:
(b) Water.

Question 10.
The unit of Calorific value of a fuel is:
(a) Joule
(b) Kilo joule/kg
(c) Kilo joule
(d) None of the above.
Answer:
(b) Kilo joule/kg.

Very Short Answer Type Questions

Question 1.
List the fuels used in rural areas in our country.
Answer:
Wood, agricultural wastes and cow-dung cakes.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Question 2.
Which of the following solid fuels has the highest heat value: Cow-dung cakes, coal, wood?
Answer:
Coal.

Question 3.
Name the most commonly used liquid fuel in Indian homes.
Answer:
Kerosene.

Question 4.
Name three liquid fuels.
Answer:
Kerosene oil, Petrol, Diesel.

Question 5.
When fuels burn, what do they produce?
Answer:
Heat and light.

Question 6.
What is ignition temperature?
Answer:
Ignition temperature. The lowest temperature at which a substance catches fire in the presence of oxygen, is called its ignition temperature.

Question 7.
Name two liquids which have low ignition temperatures.
Answer:

  1. Alcohol and
  2. ether.

Question 8.
What type of fire èxtinguisher is used to extinguish fire caused by
electricity?
Answer:
Carbon tetrachioride (CCl4) fire extinguisher.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Question 9.
What is combustion ?
Answer:
Combustion.
It is the process of heating of a substance in the presence of oxygen with the evolution of heat and light.
It is an oxidation reaction in which substance (fuel) burns in the presence of oxygen so as to liberate heat and light.

Question 10.
Define heat value of a fuel.
Answer:
Heat value of fuel. The amount of heat liberated when 1 kg of substance is burned, is called heat value of that fuel.

Question 11.
Name the type of fire extinguisher used for extinguishing oil fires.
Answer:
Foam type fire extinguisher.

Question 12.
Why charcoal is considered better fuel than wood ?
Answer:
It is because calorific value of charcoal is higher than that of wood.

Question 13.
Name the zones of a candle flame.
Answer:

  1. Cold innermost zone,
  2. middle zone,
  3. outermost non-luminous zone.

Question 14.
Name two substances which may be effective in fire fighting.
Answer:
Water and Foam.

Question 15.
Name three combustible substances.
Answer:
Paper, wood and cooking gas are three combustible substances.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Short Answer Type Questions

Question 1.
What are fuels ? In which different states fuels are found?
Answer:
Fuels. The materials which are burnt to produce heat and light, are called
fuels.
Fuels are found in three states:

  1. Solid (wood, coal, charcoal etc.)
  2. Liquid (petrol, kerosene, diesel)
  3. Gases (natural gas, coal gas, bio-gas etc).
    Fuels are found in Maharashtra and Gujarat states.

Question 2.
How will you prove that air is required for combustion?
Answer:
A burning coal or wood piece stops burning after some time, if it is covered with a glass vessel. This is because the supply of air is cut off, which stops combustion. If air is blown on this burning piece, it again starts burning with a blaze. It is therefore, concluded that air (supporter of combustion) is required for burning of a substance.

Question 3.
How can accidental fires be extinguished?
Answer:
Accidental fires can be extinguished by controlling any one of the three conditions responsible for producing fire:

  1. by cutting supply of air (oxygen) so that the combustible substance does not come in contact with the supporter of combustion.
  2. by cooling the burning substance or by lowering its ignition temperature.
  3. by removing nearby combustible substances so that fire does not spread.

Question 4.
Why do Goldsmiths use a blow-pipe?
Answer:
Goldsmiths use a blow-pipe to intensify a kerosene lamp flame for moulding pieces of gold or silver into desired shapes. The air blown through the pipe aids combustion of unburnt particles of fuel, thereby making the flame hotter.

Question 5.
Why do combustible substances not catch fire on their own ?
Answer:
Combustible substances cannot catch fire on their own as their ignition temperature is higher than normal temperature. When the temperature is lowered than ignition temperature, they catch fire.

Question 6.
Explain Ignition temperature, combustible substance, supporter of combustion in reference to conditions of combustion.
Answer:
Ignition temperature is the minimum temperature at which fuel catches fire. Each substance has definite ignition temperature below which it will not catch fire.

Combustible substance is that which readily catches fire. Paper, LPG, cloth etc. are combustible substances.

Supporter of combustion is that substance which helps in burning the combustible substance. Combustible substances like petrol, LPG will not burn till supporter of combustion like oxygen is supplied in ample amount.

Question 7.
Given the reaction:
C + O2 → CO2 + 385 kJ
Calculate the calorific value of carbon (atomic weight of C = 12, O = 16).
Solution:
According to equation, 1 mole of carbon or 12 g of carbon on burning produce 385 kJ of heat.
Thus
12 g of carbon produce heat = 385 kJ
1 g of carbon produces heat = \(\frac{385}{12}\)
∴ Calorific value of carbon = 32.1 kJ/g

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Question 8.
Why is a match stick lighted on rubbing it on the rough surface provided on the side of the match box ?
Answer:
This is due to the fact that when we rub the match stick on the rough surface of the match box, the work done during rubbing produces heat due to friction. This heat raises the temperature of the chemical present on the match stick head to its ignition temperature. Therefore, the chemical substance catches fire and the match stick starts burning.

Question 9.
Why is coke considered a better fuel than coal ? Give four reasons.
Answer:
Coke is considered a better fuel than coal because of the following reasons:

  1. Coke has higher calorific value than coal.
  2. Ignition temperature of coke is less than that of coal.
  3. Coke produces less smoke than coal.
  4. Coal on burning produces some pollutants like CO2, CO and small quantities of SO2 whereas coke does not
    produce these pollutants.

Question 10.
What do you mean by fire fighting ?
Answer:
Fire Fighting.
By fire fighting we mean to put out the fire. A fire may be due to an accident, short circuiting or human negligence. The combustion of a substance requires combustible substances, oxygen (or air) and heat. Therefore, to put out fire the air or oxygen supply should be cut off.

Question 11.
What should you do to put out the fire ?
Answer:
A fire may be due to an accident, short circuiting or human negligence. The combustion of a substance requires combustible substance, oxygen and heat. Therefore, to put out fire the air supply should be cut off. The fire can be put out by using carbon dioxide, water, sand etc.

Question 12.
Why should water not be used to extinguish fire due to :
(i) Kerosene or Petrol
(ii) Short circuiting ?
Answer:
(i) This is because kerosene and petrol being lighter than water, float on it and may further spread fire.

(ii) This is because water conducts electricity and it can cause a fatal shock to the person who is putting out the fire.

Question 13.
Why do we wrap a blanket around a person who has caught in lire ?
Answer:
When a person is caught in fire is wrapped with blanket does not get proper supply of oxygen which is necessary for combustion to take place.

Question 14.
Why are we advised not to sleep in a room with a burning coal ingithi in it ?
Answer:
In a closed room there is limited supply of oxygen and due to incomplete combustion of coal, carbon monooxide gas is produced. This gas is poisonous and may prove fatal. So we are advised not to sleep in a closed room with burning coal ingithi in it.

PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame

Question 15.
Explain Global warming.
Answer:
Global Warming. Combustion of most fuels releases carbondioxide in the air resulting in the increase of temperature of the atmosphere which is believed to be the cause of Global warming. Global warming results in melting of polar glaciers causing floods in the low lying coastal areas.

Question 16.
What is acid rain ?
Answer:
Acid Rain.
Burning of coal and diesel releases sulphur dioxide gas which is very pungent and suffocating. Moreover, petrol engines give off oxides of nitrogen. These oxides of sulphur and nitrogen dissolve in water of rain to form acids. Such rain is called Acid rain.

Question 17.
Why does the flame shown in the picture extinguishes when a glass jar is put on the burning candle ?
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 5
Answer:
We know that oxygen is necessary for burning but when we put a glass jar on the burning candle, the amount of oxygen becomes less. The flame of candle extinguishes because of shortage of oxygen.

Long Answer Type Questions

Question 1.
Discuss the various combustion zones of a candle flame with the help of a diagram.
or
Explain the zones of candle with the help of a diagram.
Answer:
PSEB 8th Class Science Solutions Chapter 6 Combustion and Flame 6
A candle flame has three distinct zones.
1. Dark inner Zone
2. Luminous Zone
3. Non-luminous Zone.

1. Dark inner zone.
The innermost zone is dafk and is the coldest part of the flame. It consists largely of the hot vapours of wax (the combustible material). Introduce one end of a glass tube in the zone, you will see white vapours coming out from the other end of the tube. On being lighted with a matchstick, these emerging vapours burn with a flame.

2. Luminous Zone.
The middle zone is a bright luminous zone. In this zone the fuel partially burns forming carbon particles. It is the glow of these particles that makes this zone luminous. The carbon particles leave the flame as smoke and soot.

3. Non-luminous Zone.
It is the outer zone which is faintly bluish in colour. In this zone oxygen from the air mixes with the fuel bringing about complete combustion. This zone is the outermost non-luminous zone. It has the highest temperature of around 1800°C.

Question 2.
Describe
(i) Rapid combustion
(ii) Spontaneous combustion
(iii) Slow combustion
(iv) Explosion.
Answer:
(i) Rapid Combustion.
The oxidation reaction in which heat and light is produced in a short time is called rapid combustion. For example, when a burning splinter is brought near the gas burner, the gas tap of which is opened, the gas immediately starts burning with the production of heat and light. Similarly, a candle starts burning when a burning splinter is brought close to its wick.

(ii) Spontaneous Combustion.
Combustion which takes place without the application of any external heat is known as spontaneous combustion.
White phosphorus is the best example of a substance burning with spontaneous combustion.

(iii) Slow Combustion.
It is a slow oxidation process in which no light is produced. In such a reaction the heat liberated is at such a low rate that we cannot feel it.
Rusting of iron and the process of respiration are examples of slow combustion.

(iv) Explosion.
Such a process of combustion, where a large number of gases with the evolution of the tremendous amount of heat and light are evolved is called an explosion. During the Diwali festival, we observe that certain crackers explode only when pressure is applied. In this process, the oxidation of the chemicals in the cracker takes place at a very high speed. Large amounts of gases are liberated with the evolution of a tremendous amount of heat and light.
Gunshot, when fired, is called an explosion.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 2 Microorganisms: Friend and Foe Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe

PSEB 8th Class Science Guide Microorganisms: Friend and Foe Textbook Questions and Answers

Exercises

Question 1.
Fill in the blanks:
(а) Micro-organisms can be seen with the help of a ……………. .
Answer:
microscope

(b) Blue green algae fix ……………….. directly from air to enhance fertility of soil.
Answer:
nitrogen

(c) Alcohol is produced with the help of …………………
Answer:
yeast

(d) Cholera is caused by ……………. .
Answer:
bacteria

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 2.
Tick the correct answer:
(a) Yeast is used in the production of:
(i) sugar
(ii) alcohol
(iii) hydrochloric acid
(iv) oxygen.
Answer:
(ii) alcohol

(b) The following is an antibiotic :
(i) Sodium bicarbonate
(ii) Streptomycin
(iii) Alcohol
(iv) Yeast.
Answer:
(ii) streptomycin.

(c) Carrier of malaria-causing protozoan is:
(i) female anopheles mosquito
(ii) cockroach
(iii) housefly
(iv) butterfly.
Answer:
(i) female anopheles mosquito.

(d) The most common carrier of communicable diseases is :
(i) ant
(ii) housefly
(iii) dragonfly
(iv) spider.
Answer:
(ii) housefly.

(e) The bread of idli dough rises because of:
(i) heat
(ii) grinding
(iii) growth of yeast cells
(iv) kneading.
Answer:
(iii) growth of yeast cell.

(f) The process of conversion of sugar into alcohol is called:
(i) nitrogen fixation
(ii) moulding
(iii) fermentation
(iv) infection.
Answer:
(iii) fermentation.

Question 3.
Match the organisms in Column ‘A’ with their action in Column ‘B’

Column A Column B
(i) Bacteria (a) Fixing nitrogen
(ii) Rhizobium (b) Setting of curd
(iii) Lactobacillus (c) Baking of bread
(iv) Yeast (d) Causing malaria
(v) A protozoan (e) Causing cholera
(vi) A virus (f) Causing AIDS
(g) Producing antibodies

Answer:

Column A Column B
(i) Bacteria (а) Causing cholera
(ii) Rhizobium (b) Fixing nitrogen
(iii) Lactobacillus (c) Setting of curd
(iv) Yeast (d) Baking of bread
(v) A protozoan (e) Causing malaria
(vi) A virus (f) Causing AIDS

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 4.
Can micro-organisms be seen with the naked eye ? If not, how can they be seen ?
Answer:
No, micro-organisms cannot be seen with naked eye because they are too small. So, we can only see them under microscope.

Question 5.
What are the major groups of micro-organisms ?
Answer:
The various groups of micro-organisms are:

  1. Bacteria
  2. fungi
  3. protozoa
  4. algae
  5. virus.

Question 6.
Name the micro-organisms which can fix atmospheric nitrogen in the soil.
Answer:

  1. Rhizobium bacteria
  2. Blue green algae.

Question 7.
Write 10 lines on the usefulness of microorganisms in our lives.
Answer:
Micro-organisms are bacteria, fungi, algae and protozoans. The beneficial aspects of Micro-organisms are as given ahead:
Beneficial aspects of Bacteria:

  1. Formation of milk products like curd and cheese.
  2. Tenderization of meat by breaking down tough muscle fibre.
  3. Formation of vinegar and wines.
  4. Decomposition of organic matter.
  5. Tanning of leather.
  6. Conversion of atmospheric nitrogen to usable nitrogenous compounds.

Beneficial aspects of Fungi:

  1. Production of bakery products like bread and cakes.
  2. Other products like idli, dosa, processed cheese, etc.
  3. Beverages like wines, beers, etc.
  4. Mushrooms are edible fungi.
  5. Medicines such as penicillin are made from fungi.

Beneficial aspects of Algae:
They help in the production of organic matter through photosynthesis which provides food to aquatic animals.

  1. Algae cell extracts like agar and alginic acid are used for preparing medicines, food and cosmetics, etc. Kelp that is a brown algae is a rich source of iodine and potassium.
  2. The cell walls of diatom (an alga) are a natural source of fine silica.
  3. Many sea weeds are used as food in China and Japan.

Beneficial aspects of Protozoans:

  1. They form an important link in the food chain.
  2. They feed on fungi and bacteria. Mix it with potato glucose solution prepared earlier. Store the mixture so obtained in the suitable container. The PDA medium is ready and can now be used to culture microorganisms in petri dishes or test tubes.

Question 8.
Write a short paragraph on the harms caused by microorganisms.
Answer:
Harmful effects of Microorganisms:
1. These microorganisms cause a large variety of diseases in plants, animals and human beings.
2. They spoil food items as well as other articles like clothes, leather etc.
3. Micro-organisms spoil food by:

  • breaking down its molecules and make new products called (amines) which are generally smelly. This changes its chemical composition as well as its texture and physical appearance.
  • some microbes secrete poisonous substances called toxins which if consumed lead to food poisoning.
  • micro-organisms grow in the food and sometimes form a whole colony consisting of such large numbers that this food, if consumed can cause illness. It is called food poisoning.

Question 9.
What are antibiotics ? What precautions must be taken while taking antibiotics ?
Answer:
Antibiotics. These are those chemical secretions which are secreted by certain microorganisms and inhibits the growth of other microorganisms without harming the host.
Alexander Fleming, an English scientist in 1929, discovered Penicillin.
Precautions to be taken while taking antibiotics
Given ahead precautions should be taken while taking antibiotics:

  1. Antibiotics should be taken only on the advice of a qualified doctor,
  2. You must finish the course prescribed by the doctor,
  3. Antibiotics, however, are not effective against cold and flu as they are caused by viruses.

PSEB Solutions for Class 8 Science Microorganisms: Friend and Foe Important Questions and Answers

Multiple Choice Questions

Question 1.
The following slide shows which micro-organism ?
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 1
(a) Spirogyra
(b) Amoeba
(c) Bacteria
(d) Fungi on bread.
Answer:
(c) Bacteria.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 2.
Is of which micro-organism is shown in the diagram ?
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 2
(a) Spirogyra
(b) Amoeba
(c) Bacteria
(d) Fungi on bread
Answer:
(c) Bacteria

Question 3.
The slide which is being shown below with the help of microscope is of which micro-organism ?
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 3
(a) Amoeba
(b) Bacteria
(e) Paramecium
(d) Virus
Answer:
(d) Virus.

Question 4.
Which of the following micro-organisms can be seen only with the help of microscope ?
(a) Virus
(b) Bacteria
(c) Yeast
(d) All of the above.
Answer:
(d) All of the above.

Question 5.
Today the teacher in the class showed a slide to his students with the help of microscope. To which micro-organism does this slide belong ?
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 4
(a) Amoeba
(b) Bacteria
(e) Paramecium
(d) Penciliam
Answer:
(c) Paramecium.

Question 6.
For what purpose yeast is used ?
(a) Sugar
(b) Wine
(c) Hydrocloride Acid
(d) Oxygen
Answer:
(b) Wine

Question 7.
Which of the following is antibiotics ?
(a) Sodium Bicarbonate
(b) Streptomycin
(c) Alcohol
(d) Yeast
Answer:
(b) Streptomycin.

Question 8.
The carrier of malaria-causing protozoan is:
(a) Female anopheles mosquito
(b) Cockroach
(c) Housefly
(d) Butterfly
Answer:
(a) Female anopheles mosquito.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 9.
The most common carrier of communicable diseases is:
(a) Ant
(6) Housefly
(c) Dragonfly
(d) Spider.
Answer:
(b) Housefly

Question 10.
The bread or idli dough rises because of:
(a) Heat
(b) Grinding
(c) The growth of yeast cells
(d) Kneeding
Answer:
(c) The growth of yeast cells.

Question 11.
The process of conversion of sugar into alcohol is called:
(a) Nitrogen fixation
(b) Moulding
(c) Fermentation
(d) Infection.
Answer:
(c) Fermentation.

Question 12.
Which instrument is used to see micro-organisms ?
(a) Magnifying glass
(b) Microscope
(c) Telescope
(d) All the above.
Answer:
(b) Microscope.

Question 13.
Which of the following micro-organisms is responsible for causing cholera ?.
(a) Virus
(b) Protozoa
(c) Bacteria
(d) None of these.
Answer:
(c) Bacteria.

Very Short Answer Type Questions

Question 1.
Fill in the blanks:

1. Microorganisms can be seen with the aid of ……………….. .
Answer:
microscope

2. Bacteria normally multiply by ……………….. .
Answer:
binary fission

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

3. Disease producing microbes are called ……………….. .
Answer:
pathogens

4. The poisonous substances produced by some pathogenic bacteria are known as ……………… .
Answer:
toxins

5. Algae can make their own food because they can ………………… .
Answer:
photo- synthesise

6. The chief source of food for fishes is ……………….. .
Answer:
algae

7. The product of algae used for raising bacterial culture is called ……………….. .
Answer:
agar

8. Algae are plant-like but ……………….. are animal-like.
Answer:
protozoans

9. Mushroom is a type of ………………. .
Answer:
fungus

10. Microorganisms which form the borderline between the living and nonliving world are called …………..
Answer:
viruses

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 2.
Define microscope.
Answer:
Microscope. It is an optical instrument which enables us to see the very tiny organisms called microorganisms.

Question 3.
Which micro-organism lies on the borderline dividing the living world from the non-living ?
Answer:
Virus lies on the borderline dividing the living and non-living.

Question 4.
Name four antibiotics.
Answer:
Penicillin, Streptomycin, Tetracycline and Gramicidin.

Question 5.
What are micro-organisms ?
Answer:
Micro-organisms. These are small organisms which are too small to be seen with naked eyes.

Question 6.
Name the major groups of micro organisms.
Answer:
The major groups of microorganisms are:
Bacteria, Fungi, Protozoa, Algae and Viruses.

Question 7.
Write the average size of bacterium.
Answer:
1.25 mm (1μm = \(\frac{1}{1000}\) mm) in diameter.

Question 8.
Which is the smallest bacteria ?
Answer:
The smallest is rod-shaped bacteria measuring 0.15 mm.

Question 9.
Name the largest bacteria.
Answer:
Spiral shaped bacteria measuring upto 15 mm in length and 1.5 μm in diameter.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 10.
Name two examples of Bacillus.
Answer:
Lactobacillus, Pseudomonas.

Question 11.
Write examples of blue-green algae.
Answer:
Nostoc, Anabaena, Oscillatoria.

Question 12.
How much nitrogen is fixed by blue-green algae in a paddy field in a year ?
Answer:
About 625 kg of nitrogen in one square km area.

Question 13.
Which micro-organism is used in the preparation of bread and alcohol ?
Answer:
Yeast.

Question 14.
Name two nitrogen fixing algae.
Answer:
Nostoc and Anabaena.

Question 15.
What are the two major groups of fungi ?
Answer:
Yeast and moulds.

Question 16.
Under which group of micro-organisms Amoeba fall ?
Answer:
Protozoa.

Question 17.
Name two antibiotics.
Answer:

  1. Streptomycin
  2. Erythromycin.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 18.
Who discovered vaccination ?
Answer:
Louis Pasteur.

Question 19.
Name unicellular micro-organism.
Answer:
Bacteria, Protozoa.

Question 20.
Name multicellular micro-organisms.
Answer:
Algae, Fungi.

Question 21.
Name a micro-organism which can live independently.
Answer:
Amoeba.

Question 22.
Name micro-organisms which live in groups.
Answer:
Fungi and Bacteria.

Question 23.
For which purpose antibiotics are used ?
Answer:
Antibiotics are used for curing diseases.

Question 24.
Which micro-organisms are used to prepare antiboitics ?
Answer:
Bacteria and Fungi.

Question 25.
When and who first invented first antiboitic ?
Answer:
Alexander Fleming in 1929, invented first antibiotic.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Short Answer Type Questions

Question 1.
Are all micro-organisms of similar sizes ?
Answer:
No, all micro-organisms are not of similar size. The size of bacteria ranges from 0.2 to 100 microns. The size of yeast ranges from 5 to 10 micron and that of moulds from 2 to 10 micron. The size of algae ranges from 1 micron to several metres in length. The size of protozoa ranges from 2 to 200 microns. The size of viruses ranges from 0.015 to 0.2 micron.

Question 2.
Give examples of a slow and fast growing bacteria.
Answer:
Examples of slow growing bacteria:

  1. Mycobacterium tuberculi
  2. Mycobacterium leprae

Examples of fast growing bacteria:

  1. Pseudomonas
  2. E. coli.

Question 3.
What are the two groups of organisms of fungi ?
Answer:
Fungi consists of two main groups:
Yeasts and Moulds.

  1. Yeasts. They are usually unicellular.
  2. Moulds. They are usually multicellular and have a filament-like appearance.

Question 4.
How do microbes survive adverse conditions ?
Answer:
Micro-organisms are very hardy. They can survive under extreme conditions of temperature and dryness by forming a hard outer coating called a cyst. Within this protective shell, they remain inactive as such, until more favourable conditions return. They, then emerge from their shell, multiply and go through their life cycles.

Question 5.
In what ways, are viruses different from other microbes ? Name two plant viruses and two animal viruses.
Answer:
Viruses are different from other microbes due to the following facts:
1. They are the smallest microbes.
2. They cannot be totally called living beings because they do not grow on their own.
3. They are mostly harmful and cause a number of diseases.

Plant viruses.

  1. Tobacco mosaic virus (TMV)
  2. Bacteriophage.

Animal viruses.

  1. Foot and mouth disease virus (FMDV)
  2. Measle virus.

Question 6.
Why are viruses placed on the border line between living and nonliving things ?
Answer:
Viruses resemble living objects due to following reasons:

  1. They contain nucleic acids.
  2. They grow and multiply like living beings.

Viruses resemble non-living things due to the following reasons:

  1. They do not contain cytoplasm and definite nucleus.
  2. They can be crystallized like salts or sugar.

Question 7.
Differentiate between yeasts and moulds.
Answer:
Differences between Yeasts and Moulds

Yeasts Moulds
1. They are unicellular. 1. They are multi-cellular.
2. They range in size from 5-10 microns. 2. They range in size from 2-10 microns.
3. Yeasts are both aerobic as well as anaerobic. 3. Moulds are aerobic.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 8.
Write some examples of commercial products obtained from fungi.
Answer:

  1. Some fungi are directly used in the preparation of dishes.
  2. Some antibiotics are obtained from fungus.
  3. Some fungi are used in the preparation of bread and alcohol.
  4. Wines, beers are prepared with the help of certain fungi.

Question 9.
What are Bacteriophages ?
Answer:
Bacteriophage. Viruses are heterotrophic. Virus which depend on bacteria are called bacterial viruses or bacteriophages.
It is shaped like a rod. They destroy bacteria which are responsible for spoilage of organic matter.
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 5

Question 10.
Describe the various products involving action of fungi.
Answer:
The various products involved are as follows:

  1. Bakery products. Bread and cakes from wheat flour.
  2. Food products. Wines, beers from fruit juices or barley ; idli and dosa from a mixture of powdered rice and dal.
  3. Processed cheese.
  4. Some fungi such as mushrooms are directly used as food products.
  5. Some very important medicines, such as penicillin are made from fungi.
  6. Moulds spoil food, damage potato and crop plants, corn and wheat. They also cause rotting of clothes, shoes and wooden materials.
  7. Some fungi cause diseases like athlete’s foot and ringworm.

Question 11.
How is bread formed ?
Answer:
When yeast together with some sugar and warm water is mixed with flour (atta or maida), the dough begins to rise. The presence of sugar and the warmth stimulates rapid growth of the yeast cells. During their reproduction, yeast cells produce carbon dioxide. Bubbles of CO2 fill the dough and make it rise. When baked into a loaf, the bread becomes light and spongy.

Question 12.
How is the mixture of ground rice and dal made sour ?
Answer:
The mixture of ground rice and dal is allowed to stand for a few hours. It becomes sour. It is the growth of yeast cells that causes the mixture to rise and become sour.

Question 13.
Suggest some methods to prevent the growth of moulds.
Answer:

  1. Keep the things at low temperatures.
  2. Keep the things in clean closed containers.
  3. Keep the things in dry condition in dry storage.
  4. Keep the food in the form of syrups, pickles, in the form of preserved food.
  5. Keep the articles away from the reach of microorganisms present in the air.

Question 14.
Write the importance of fungi in medicines.
Answer:
Antibiotics are obtained from fungi, and Penicillin is obtained from the fungus, Griscofulvin is extracted from the fungus Griscofulvum.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 15.
What are the major differences between algae and fungi ?
Answer:

Algae Fungi
1. Green in colour. 1. Colourless or non-green.
2. Outer cell wall is formed by cellulose. 2. Outer cell is formed of fungus cellulose.
3. Autotrophic. 4. Saprophytic or Parasitic.
4. Aquatic in habitat. 3. Heterotrophic.
5. Grow on wet surfaces. 5. Grow on moist organic surface.

Question 16.
What are vaccines ?
Answer:
Vaccines.
A vaccine consists of antigens of mild strains of pathogens of a specific disease. When injected into the blood stream, it stimulates while blood cells to produce antibodies.

Question 17.
Describe the role of blue green algae in the fertility of soil.
Answer:
Blue green algae play an important role in the fertility of soil due to the following reasons:

  1. They make the nitrogen available to the soil.
  2. They increase the humus content of the soil.
  3. They support the crop growth.
  4. They improve the water holding capacity of the soil.

Question 18.
Describe some of the important landmarks in the study of microorganisms.
Answer:
Important landmarks in the study of microorganisms are as follows:

Name of the scientist Year Contribution
Robert Hooke 1665 Observed cork cells, spermatozoa and bacteria using a simple microscope and named them as tiny animalcules.
Louis Pasteur 1857

1859

Fermentation is a biochemical process.

Microbes produce only from pre-existing microbes of same species.

Robert Koch 1872 Tubercle bacillus is the main cause of tuberculosis germ theory of disease.
Shikabasaburo

Alexander Fleming

1889

1929

Tetanus disease is due to Tetanus bacillus.

Antibiotic penicillin from Penicillium notatum (a fungus).

Question 19.
What is food poisoning ?
Answer:
Food Poisoning. Sometimes the microorganisms grow on our food items and spoil it. When we eat this food, it causes food poisoning. It causes serious illness and even death.

Question 20.
Explain the following terms in brief:
(a) Immunity
(b) Antibodies
(c) Vaccination.
Answer:
(a) Immunity.
Immunity is the ability of a person (or organism) to resist the development of a disease even when infective dose of the pathogen has been introduced. The science of development of resistance or defence to the causative agents of the diseases is termed as immunology. Foundations of immunology were laid by Edward Jenner (1796) who successfully developed first vaccine against small pox.

(b) Antibodies.
It is a substance occurring naturally in the blood or produced in response to the presence of antigen which is able to overcome the toxic effect of an antigen.

(c) Vaccination.
It is a process of injecting a substance (Vaccine) into a healthy person in order to develop immunity against a specific disease.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Question 21.
Write three ways of entering microorgnisms into the body.
Answer:
Entry of microorganisms into the body

  1. Through the air we inhale.
  2. Through the water we drink, and the food we eat.
  3. Through skin.

Question 22.
What is vaccine ? Describe the importance of vaccination.
Answer:
Vaccine. A vaccine consists of a small amount of dead or weakened germs of a particular disease that are injected into the body. Injecting or swallowing a vaccine is called the vaccination when the vaccine is injected into our body. Our body produces antibodies that fight with those dead or weakened germs. These antibodies stay in our body to prevent the future attack of such kind of microbes. Thus, our body develops immunity against the particular disease for which vaccination is provided.

Question 23.
Write a note on cyanobacterial cell.
Answer:
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 6
Cyanobacteria.
These are chlorophyll containing autotrophic microscopic bacteria, also called blue green algae. They may be filamentous or colonial in form. Main examples are Oscillatoria, Spirulina, Nostoc, Stigonema.

A typical cyanobacterial cell consists of a four layered cell-wall followed by plasma membrane. The cytoplasm contains gas vacuoles, ribosomes photosynthetic pigments such as chlorophyll a, carotenoids and circular double stranded naked DNA. The reserve food is in the form of cyanophycean starch, liquid globules and cyanophycean protein granules.

Question 24.
What are diatoms ? Sketch a few examples of diatoms.
Answer:
Diatoms.
They are microscopic unicellular algae found in fresh water springs, estuaries and marine water of ocean. They occur mostly as individual cells and some form colonies. Diatoms deposit silicon dioxide in their cell wall. They reproduce asexually as well sexually.
Examples of Diatoms
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 7

Question 25.
Ajit kneaded 1/2 kg maida along with lukewarm water. He also added some sugar and yeast in it. What will be the effect on kneaded flour after 2 hours ? Give reason for your answer.
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 8
Answer:
The dough begins to rise. The presence of sugar and yeast stimulates rapid growh of the yeast cells. During their reproduction, yeast cells produce carbon dioxide. Bubbles of CO2 fill the dough and make it rise.

PSEB 8th Class Science Solutions Chapter 2 Microorganisms: Friend and Foe

Long Answer Type Questions

Question 1.
Sketch few of the micro-organisms.
Answer:
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 9

PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 11

Question 2.
Give in a tabulated form some of the common diseases affecting man and their mode of transmission and methods of prevention.
Answer:
Some Common Human Diseases Caused by Micro-organisms:
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 12
PSEB 8th Class Science Solutions Chapter 2 Microorganisms Friend and Foe 13

Question 3.
Give some of the common plant diseases caused by micro-organisms.
Answer:
Common Plant Diseases Caused by Micro-organisms

Plant Diseases Micro-organism Mode of Transmission
Citrus canker Bacteria Air
Rust of wheat Fungi Insects and seeds
Yellow vein mosaic of Ladyfinger Virus Insect

Question 4.
What is meant by food preservation? Explain the different methods of food preservation used for foods.
Answer:
Food Preservation. The processes by which the perishable food materials are treated to prevent their spoilage and retain their nutritive value for long periods
is called food preservation.
The substances used for food preservation are called food preservatives.
Different Methods of Food Preservation:

1. Dehydration and Sun Drying.
The process of removal of water from fruits, vegetables is called dehydration. It reduces the moisture content of food materials and, therefore, prevents the food from spoilage. Drying in the sun is one of the oldest methods of food preservation.

2. Preservation by Salt and Sugar.
Common salt and sugar are good preservatives. These stop the bacterial growth in the food material. Pickles, jam, jelly, ketchup, squash, etc. are preserved by adding salt and sugar.

3. Deep Freezing. It is a direct method for the prevention of bacterial growth. In this method, the food materials are cooled below 0 C. Fruits vegetables, meat, fish, etc. can be easily preserved by this method.

4. Chemical Preservation. Certain chemicals can be used to preserve food. The substances which are added to the food materials to prevent their spoilage are called food preservatives. Benzoic acid, Potassium metabisulphite, etc. can be used. Irradiation, canning, and bottling are also used for the preservation of food.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Punjab State Board PSEB 8th Class Social Science Book Solutions Geography Chapter 1 Resources – Types and Conservation Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Social Science Geography Chapter 1 Resources – Types and Conservation

SST Guide for Class 8 PSEB Resources – Types and Conservation Textbook Questions and Answers

I. Answer the following questions in 1-15 words :

Question 1.
What do you understand by the term ‘resources’?
Answer:
All the useful elements of the environment which satisfy human needs are called resources. Resources are called ‘Gifts of nature’ such as rocks, minerals, soil, rivers, plants, and animals. These are valuable for mankind. Man’s surroundings provide him with resources.

Question 2.
Which are the Natural Resources and who provides us?
Answer:
Forests, minerals, soil, and solar energy are natural resources. These make our environment or surroundings. These natural surroundings provide rsesources.

Question 3.
List all the types of resources.
Answer:
The three categories of resources are :

  1. Natural Resources
  2. Human Resources
  3. Human Made Resources.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 4.
Define ‘soil’.
Answer:
The loose and unconsolidated material which forms the upper layer of the crust is called soil. Soil is formed by the breaking of parent rock.

Question 5.
What do we get from Seas?
Answer:
The big water bodies are called seas. Seas provide us organic minerals and power resources, fish, pearls, diamonds, etc. At some places, petroleum is also obtained from sea.

Question 6.
How can you conserve the resources properly?
Answer:
The proper and planned use of resources help in the conservation of resources. These should not be misused.These should not be wasted or destroyed.

II. Answer the following questions in 50-60 words :

Question 1.
Differentiate between Biotic and Abiotic resources.
Answer:

Biotic Resources Abiotic Resources
1. These are obtained from living things. 1. These are obtained from non-living things.
2. Plants and animals are its examples. 2. Minerals and rocks are examples.
3. These are found in Biosphere and provide food, energy (coal and petroleum) and raw materials. 3. These are found on lithosphere and provide raw materials for industries.

Land: Land is the basis of human activities. It helps in agriculture, setting up of industries, means of transportation, sports, tourism, etc. Houses are built on land.Question 2.
Write a short note on the importance of Land and Soil Resources.
Answer:
The following is the importance of Land and Soil :

  1. Soil: Man grows crops on soils. It provides food and other raw materials to man. Fertile soils support dense population.

Question 3.
From where do we get the minerals and where they used?
Answer:
Minerals are obtained from the interior of earth from rocks. These are metallic and non-metallic. Metallic minerals include iron, copper, gold, silver, aluminium. Non- metallic minerals include coal, mica, manganese and oil. These are used in industries. Before use, these are smelted to make pure.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 4.
Explain the Developed and Potential resources with examples.
Answer:

Potential Resources

Developed Resources

1. These are total quantity of a resource found existing in nature. 1. These are only those resources, which have been judged good for use.
2. These have not been put to use. 2. They are put to use fully for economic gain.
3. These are found everywhere. 3. These are not found everywhere.
4. Africa has 40% potential water power resources of world due to large rivers. 4. Africa has only 1% of developed water power resources of world due to lack of technology.

Question 5.
Why should we use the exhaustible resources wisely and with hesitation?
Answer:
The modern civilisation depends upon products—natural as well as man made. With the help of technology, resources are being utilised on a large scale. The exhaustible resources will not last long. 80% of the fossil fuels will be finished in one century With the exhaustion of resources, the civilisation will come to an end. Therefore conservation of resources is necessary. A balance should be maintained between population growth and utilisation of resources so that the continuity of modern civilisation goes on. The natural resources are common heritage. We have to share these with future generations.

Question 6.
What is the contribution of human resources to the development of other resources ?
Answer:
Resources are the elements of Bio-physical environment. But these become resources only when humans preserve these. Coal was always there, but it became a resource only when man used it as a source of energy. So it has been rightly said that the resources are not, they become so. Man uses technology and skill to develop resources. Machines and tools are used. Japan is a very good example where in spite of non existence of resources, the country has progressed to a great extent.

III. Answer the following questions in about 125-130 words :

Question 1.
What do you understand by the resources ? Name their types and explain their importance and methods of conservation.
Answer:
Type of Resources: Resources are generally classified into three types :

  1. natural
  2. human and
  3. human-made.

Natural or man-made resources are of various types. On the bases of life, existence, availability, level of development and utilization these resources can be divided into the following types :

  • Biotic and Abiotic Resources
  • Developed and Potential Resources
  • Exhaustible and Inexhaustible Resources
  • Soil and Land Resources
  • Marine-and Mineral Resources
  • Human Resources

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation 3
Resource Types

1. Biotic and Abiotic Resources. Biotic resources are those basic resources which originate from the living things. Approximately 85% of the world’s total food depend upon these biotic resources. Plants and other living creatures are included in these types of resources. These resources provide raw material for our industries. Coal and petroleum are also included in the category of biotic resources as they are produced from the plants and animals.
The non-living products like minerals, water etc., which are provided by the nature are called ‘Abiotic Resources’. The minerals are the base of our industry. If we do not use the minerals with care, these will exhaust very soon.

2. Developed and Potential Resources. The resources which are used for some economic gain are termed as ‘Developed resources’. On the other hand, the resources which are available but are not being used or can be used in the future are called ‘Potential Resources’. The rivers descending the mountains can be used to produce electricity and are included in the category of potential resources. When the water of these rivers is used to produce electricity then this water is known as a developed resources. The coal lying underneath the earth is a potential resource whereas the coal which is being used is considered as a developed resource.

3. Exhaustible and Inexhaustible Resources. The resources which are being depleted very fast .because of their continuous and excess use are called exhaustible resources, as petroleum products are being used very fast. The time is not very far away when there will be shortage or non-existence of these resources. Therefore, the exhaustible resources should be used wisely and carefully. ‘

The resources which get renewed as we use them are called inexhaustible resources. For example : We are using sun energy, wind energy, water and forests but these resources do not get depleted rather get renewed. These types resources are being made available continuously. ‘

4. Soil and Land Resources. Soil is a small and uppermost layer of the earth which is formed by breaking of parent rock, due to climate effect and decomposition of plants and animals. Soil is a very important resource for man. It plays an important role in the growth of plants and crops. The soils are of different types like sandy soil, clayey soil, loamy soil, alluvial soil, mountain soil, red soil, black soil etc. Man gives preference to fertile soil for growing crops. The areas with fertile soil are densely populated and are full of economic activities.
Land means the earth’s surface where man carries on his economic or other activities. Man had been using the land resource for a very long time. The land resource is being used for the purpose of agriculture, industry, to develop means of transport, sports, tourism etc. Man uses the land, keeping in view its relief, slope, type of soil, drainage or his requirements.

5. Marine and Mineral Resources Marine Resources. Water is a basic and a very important resource for man. Approximately 71% part of the earth is water. Big water bodies are called ‘seas’. These water bodies provide many biotic, mineral and energy resources. It is believed that the life on the earth started from the seas and oceans. 75% of the total land creatures originated from the water bodies. We get fish, pearls, shells, diamonds etc. from the seas in large quantities. At some places we get petroleum substances from the sea coasts. The fish provide food to the large part of the World’s population.

Mineral Resources: Mineral resources are the substances which are taken from the earth. Basically these are of two types-Metallic and non-metallic minerals. Metallic minerals include iron, copper, silver, gold, aluminium etc.

Petroleum, coal, mica, manganese etc. are some of the non-metallic minerals. The minerals are taken from different types of rocks. The minerals are the bases for our industries, therefore, much significance is attached to them.

6. Human Resources: Man has been awarded the best status of all the creatures produced by the nature. With his intelligence and ability to work, man himself is a very huge resource. Man’s capability plays an important role in the use of all other resources. The development of human resources is reflected from the development of any area. Japan is a very good example where inspite of the deficiency or non-existence of resources, the country has progressed to a great extent. The development of all other resources is incomplete till the human resource is fully developed. Man’s qualities, capacity, educational and technical qualification etc. play an important role in the development.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

IV. Activity

Question 1.
Make a list of Hydroelectricity producing dams related to Punjab. Note down the names of rivers on which these dams are situated and names of districts in which these dams have been constructed.
Answer:

Dams

Rivers

Districts

1. Bhakra Sutlej Himachal Pradesh
2. Ganguwal Nangal Hydel Channel Ropar
3. Kotla Nangal Hydel Channel Ropar
4. Pong Dam Beas Hoshiarpur
5. Thein Daam Ravi Gurdaspur
6. Mukerian Beas Hoshiarpur

PSEB 8th Class Social Science Guide Resources – Types and Conservation Important Questions and Answers

I. Multiple Choice Questions :

Question 1.
Which are the biotic resources?
(a) rocks
(b) minerals
(c) plants
(d) hills
Answer:
(c) plants.

Question 2.
What are the basis of classifying resources?
(a) life
(b) achievement
(c) use
(d) all of the above.
Answer:
(d) all of the above.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 3.
Which is not termed of human resource?
(a) knowledge
(b) efficiency
(c) intelligence
(d) transparency.
Answer:
(d) transparency.

Question 4.
Which of the following are the ubiquitous resource?
(a) air, water
(b) coal, copper
(c) iron, ore
(d) uranium.
Answer:
(a) air, water.

Question 5.
Nager coil is famous for __________
(a) coal mining
(b) windmills
(c) solar energy
(d) oil refinery.
Answer:
(b) windmills.

Question 6.
In this picture some resources are shown these resources are :
PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation 1
(a) Abiotic resources
(b) Biotic resources
(c) Ubiquitous resources
(d) Human resources.
Answer:
(b) Biotic resources.

Question 7.
We enjoy a lot the beauty of waterfalls mountains, sea etc. Thus, they are natural resources which have ______value.
(a) Ethical Value
(b) Artistic Value
(c) Aesthetic Value
(d) Economic Value.
Answer:
(c) Aesthetic Value.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 8.
The following picture shows a specific type of plant. Identify the name of this plant :
PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation 2
(a) Thermal Plant
(b) Nuclear Plant
(c) Biogas Plant
(d) Hydro electric plant
Answer:
(c) Biogas Plant.

Fill in the Blanks :

Question 1.
_______ resources are derived from living things.
Answer:
Biotic

Question 2.
Localised resources are found only in _______ place.
Answer:
certain

Question 3.
The example of human resource is _______
Answer:
people

Question 4.
Anything that satisfy human needs is called _______
Answer:
resource

Question 5.
Non living resources are called _______ resources.
Answer:
Abiotic.

True/False :

Question 1.
Solar and wind energy is an example of renewable resources.
Answer:
True

Question 2.
Environment means set of surroundings.
Answer:
True

Question 3.
Resources are generally classified into two types.
Answer:
False.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 4.
Land use depend upon relief, slope, soil etc.
Answer:
True

Question 5.
Coal and petroleum are not biotic resource.
Answer:
False.

Very Short Answer Type Questions

Question 1.
How does something become a resource?
Answer:
That thing which has a value and utility become a resource.

Question 2.
Why is modern man dependent on resources?
Answer:
In early times, human needs were limited. But now-a-days the needs have increased. So man has to depend upon many resources.

Question 3.
Explain, with examples, that the proper use of resources is real development of resources.
Answer:
Before the invention of coal, petroleum, and aeroplane, man was not aware of the Aluminium. Due to utility of Aluminium, its use increased. So we can say that proper use has led to the development of resources.

Question 4.
What are the four basis of classifying resources?
Answer:

  1. life
  2. achievement
  3. stage of development
  4. use.

Question 5.
Which resources are most important to obtain food-resources?
Answer:
To get food resources, agriculture is the most important source as it provides 85% of food resources.

Question 6.
Why coal and petroleum are biotic resources?
Answer:
Coal and petroleum are formed by organic and living plants and animals. So these are grouped as biotic resources.

Question 7.
How can you assess a country as a rich country?
Answer:
The wealth of a country is measured by its resources. The more developed resources make a country richer.

Question 8.
Why are fertile soil areas densely populated with large economic activities?
Answer:
Fertile soils help in growing crops. In fertile soils agriculture is developed. It leads to dense population and many economic activities.

Question 9.
On what factors does the landuse depend?
Answer:
Landuse depends upon relief, slope, soils, drainage and human needs.

Question 10.
What is human resource?
Answer:
Man made resources include machinery, transportation, industries. Human intelligence, knowledge and efficiency is termed as human resource.

Question 11.
Concept of Resource is changing. Why?
Answer:
The concept of resource is changing. It may expand or contract with the development of knowledge and technology.

Question 12.
Name the important types of soil.
Answer:
Sandy soil, Clayey soil, Loamy soil, Alluvial soil, Red soil, Black soil.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 13.
Classify resources on the basis of their source of origin.
Answer:
Based on their origin, resources can be biotic or abiotic. For example plants, animals, rocks, minerals, soils etc.

Question 14.
How can we conserve the resources?
Answer:
We can conserve resources by reducing consumption, recycling and reusing things.

Question 15.
What is technology?
Answer:
Technology is human made resource. It is the application of latest knowledge and skill in doing or making things.

Question 16.
The population of India is lesser than only one country. Name that country.
Answer:
China.

Short Answer Type Questions

Question 1.
What is a resource?
Answer:
All the useful elements of environment which satisfy the human needs are called resources. Resources are called ‘Gifts of nature’ such as soils, rivers, plants, animals, rocks and minerals. These are valuable for mankind.

Question 2.
Why are humans also called a resource?
Answer:
They are called a resource because by developing the human skills only the resources can be developed. Resources are not, but they become due to man.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 3.
What do you understand by the statement “natural resources have utility and value”?
Answer:
Natural resources have utility and value is true. All the materials that are available in nature have some use or value and that’s what makes them valuable.

  1. Water, air vegetation all have utility or usability, they may or may not have economic value.
  2. Metals have economic value but a landscape may not have; but both are important to satisfy human need.
  3. Time and technology makes them a resource.

Question 4.
What leads to creation of new resources?
Answer:
The knowledge, ideas, inventions and discoveries by people leads to creation of more resources. The discovery of fire led to idea of cooking and other related processes. Invention of wheels led to changes in modes of transport.

Question 5.
Discuss the role of technology in the utilisation of resources.
Answer:
Technology helps to develop the means of production. It increases the value of natural resources. Technology depends upon the human skill and technical knowledge. Mechanism helps in the better utilisation of natural resources. A resource is no resource until it is used.

Question 6.
Distinguish between Natural Resources and Human-made Resources.
Answer:

Natural Resources

Human made Resources

1. They are free gifts of nature. 1. They are not free gifts of nature.
2. They are both renewable and non-renewable. 2. They are non-renewable.
3. They help in the economic development of the country. 3. They help in economic and social development.

Question 7.
Distinguish between Exhaustible and Inexhaustible Resources.
Answer:

Exhaustible Resources

Inexhaustible Resources

1. These resources get exhausted after use. 1. These resources do not get exhausted after use.
2. These resources are regenerated after a very long time. 2. These are renewable or flow resources.
3. Minerals and metals are exhaustible resources. 3. Forests, water power are inexhaustible resources.

Question 8.
What do we mean by a reserve?
Answer:
It refers to that portion of resource which<can be developed profitably with the help of available technology.
For example : High quality iron is used for steel making. But sometimes a low grade iron ore or coal (lignite—Less than 40% carbon content) is used for steel making. Lignite coal in Neyvelli (Tamilnadu) is an example of a reserve resource.

Question 9.
What is meant by human-made resources?
Answer:
They are those resources which are created by human being with the help of machines. Some of the examples are buildings, tools etc.

Question 10.
Give two examples of human made resources.
Answer:
The human made resources are those resources which are created by human beings.

Some examples are :

  1. Buildings,
  2. Machines.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 11.
Give an account of natural resources.
Answer:
Natural Resources:
Resouces drawn from (nature) and used without much modification are called natural resources.

  • Water, soils, minerals are all natural resources.
  • Many of the resources are free gift of nature.
  • They can be used directly.
  • In some cases tools and technology are needed to use a natural resource in the best way.

Question 12.
How are natural resources classified?
Answer:
Natural resources are classified into different groups :

  • Level of development and use
  • origin
  • stock
  • distribution.

Question 13.
Why natural resources are important?
Answer:

  • These are important for the economic development of a region or a country.
  • They are the main sources of our agricultural activities.
  • They provide raw materials for the industry.
  • All activities depend on them directly or indirectly.
  • They help in maintaining the ecological balance of nature. Thus they should be used carefully.

Question 14.
What is meant by conservation?
Answer:
It means the use of the natural resources carefully without any wastage. They are important to us, so they should be used wisely so that they are not exhausted and we may have to face their scarcity.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 15.
‘Resources are not resources, they become so.’ Explain.
Answer:
Resources are elements of Bio-physical environment. But these become resources only when humans preserve these. Coal was always there, but it became a resource only when man used it as a source of energy. So it has been rightly said that resources are not resources, they become so.

Question 16.
What are the ill effects of overuse of resdUrces? What are the measures to make the earth habitate? ”
Answer:
Ill effects :
Degradation of resources: The rising demand for various resources has caused degradation or depletion of many valuable resources.

Example :

  • Overuse of soil has caused infertility in many areas.
  • Similarly widespread deforestation and killing of birds and animals have endangered many plants and animal species.
  • The quality of air, water and land resources has also been affected badly due to misuse or overuse of resources.

Question 17.
Distinguish between Renewable and Non-renewable resources.
Answer:

Renewable Resources

Non-renewable Resources

1. These have the capacity to regenerate. 1. These cannot regenerate that quickly.
2. These are free gifts of nature. 2. These are not free gifts of nature.
3. These are those resources which can be used again. 3. These cannot be used again.
4. For example air, water, etc. 4. For example coal, natural oil.

Question 18.
Future of our planet is linked with life support system. Discuss.
Answer:
Our earth is the only planet where life has been found till today. Future of our planet and its people, is linked with our ability to maintain and preserve the life support system that nature provides. This makes it our duty to ensure that the natural environment is preserved and properly managed.

Question 19.
What is sustainable development?
Answer:
By sustainable development, we mean that resources are utilised carefully so that besides meeting the present requirement it also takes care of the future generations.

Question 20.
What is our duty regarding resources?
Answer:
It is our duty to ensure that

  • The diversity of life on the earth is conserved.
  • All uses of renewable resources are sustainable.
  • The damage to natural environment system is minimised.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 21.
Distinguish between Natural Resources and Human Resources.
Answer:

Natural Resources

Human Resources

1. They are free gifts of nature. 1. They are not free gifts of nature.
2. They are both renewable and non renewable. 2. They are non renewable.
3. They help in the economic development of the country. 3. They help in the economic and social development.

Question 22.
In how many ways man uses his environment?
Answer:
Environment means set of surroundings. It provides many resources to get food, shelter and clothing. Man uses land for crops, houses, factories,- construction of transport network. Man uses minerals for industries. He uses forests for timber, herbs and shrubs. Man gets fish and other benefits from seas and oceans.

Question 23.
How are development and resources interdependent?
Answer:
Development is possible through resources. Resources are the foundations of development. These have economic significance for human beings. Land, water and air are basic requirements for agriculture. We can’t do agriculture without these resources. Minerals are basic requirement for industries. Industries cannot run without minerals. Thus development and resources are inter-dependent.

Question 24.
Distinguish between actual resources and reserve resources.
Answer:
Actual Resources. Actual resources depend upon physical conditions of environment. These are surveyed. Their quantity is determined and are actually used. Their quantity is known.

Reserve resources are a part of actual resources. These can be made useful with technology. A low grade coal-lignite is a reserved resource in some areas.

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 25.
Give one example each of developed and potential resources.
Answer:
When the water of river is used to produce electricity, it is called a developed resource. The coal underlying the earth is a potential resource.

Fill in the blanks :

Question 1.
_______ resources are derived from living things.
Answer:
Biotic

Question 2.
Localised resources are found only in places.
Answer:
certain

Question 3.
The example of human resource is _______
Answer:
people

Question 4.
Solar and wind energy is an example of _______
Answer:
Renewable resources

Question 5.
Anything that is used to satisfy a need is called a _______
Answers :
resource

PSEB 8th Class Social Science Solutions Chapter 1 Resources – Types and Conservation

Question 6.
Petroleum in _______ is an example of actual resource.
Answer:
West Asia

Question 7.
_______ is the application of latest knowledge and skill is doing or making things.
Answer:
Technology.

Long Answer Type Questions

Question 1.
Write a detailed note on the conservation of resources with special reference to marine and mineral resources.
Answer:
Conservation of Resources. Man depends upon his environment to meet his needs. He uses water, land, soil, vegetation, etc. to satisfy his needs. Man is using these resources at such an alarming rate that there will be a serious shortage of these resources in the near future. Natural resources are of a very limited supply. So conservation of resources is essential for the survival of man.

To some people, conservation means that the available resources should not be used. These should be held back. But conservation of resources means a careful and rational utilization of resources. These resources should be used intelligently for the welfare of mankind. It means careful control and management of resources so that these may be used for the benefit of future generations also. These should be preserved from reckless exploitation and wanton destruction. These resources should not be wasted in a short time. The resources should be maintained in a healthy condition for their use so as to achieve a high standard of living for mankind.

Importance:
Conservation of all resources has an economic, scientific, and aesthetic value for mankind :

  • Conservation of resources is necessary as these are the basis of the economic activities of man.
  • Resources must be conserved to meet the different human needs.
  • Conservation of resources is essential as life depends on these useful elements of the environment such as air, water, soil, rocks, forests, and water bodies.
  • Many areas of the world are still under-developed because the resources of these areas have not been used in a planned and rational manner.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 5 Coal and Petroleum Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 5 Coal and Petroleum

PSEB 8th Class Science Guide Coal and Petroleum Textbook Questions and Answers

Exercises

Question 1.
What are the advantages of using CNG and LPG as fuels?
Answer:
Advantages of LPG:

LPG is considered to be a better fuel because of the following reasons:

  1. LPG has a high calorific value. Its calorific value is about 50 kJ/g. This means that when 1 gram of LPG burns in a gas stove, it produces about 50 kilo-joules of heat energy.
  2. It burns with a smokeless flame and so does not cause pollution.
  3. LPG does not produce any poisonous gases on burning.
  4. LPG is easy to handle and convenient to store.
  5. It undergoes complete combustion.
  6. LPG is a very neat and clean domestic fuel.

Advantage of CNG:
It does not cause air pollution.

Question 2.
Name the petroleum product used for surfacing of roads.
Answer:
Bitumen.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 3.
Describe how coal is formed from dead vegetation. What is this process called ?
Answer:
Formation of coal from dead vegetation:
About 300 million years ago, the forests got buried under the soil. They were compressed by soil deposits and temperature also rose as they sank deeper and deeper. Due to this high temperature and pressure coal was formed from dead vegetation by process of carbonisation.

Question 4.
Fill in the blanks.
(a) Fossil fuels are …………….. , …………… and ……………
(b) Process of separation of different constituents from petroleum is called ………………… .
(c) Least polluting fuel for vehicle is ………………..
Answer:
(a) Coal, petroleum, natural gas.
(b) refining.
(c) CNG (Compressed natural gas).

Question 5.
Tick True/False against the following statements.
(a) Fossil fuels can be made in the laboratory.
Answer:
False

(b) CNG is more polluting fuel than petrol.
Answer:
False

(c) Coke is almost pure form of carbon.
Answer:
True

(d) Coal tar is a mixture of various substances.
Answer:
True

(e) Kerosene is not a fossil fuel.
Answer:
True

Question 6.
Explain why fossil fuels are exhaustible natural resources.
Answer:
Fossil fuels are formed from remains of dead organisms and it took million of years to get these organisms converted into fuels. The known reserves of these fuels are limited and so, these are exhaustible fuels.

Question 7.
Describe the characteristics and uses of coke.
Answer:
Characteristics of Coke:

  1. It is tough, porous and black substance.
  2. It is pure form of carbon.

Uses of Coke:

  1. It is used to manufacture artificial graphite.
  2. It is used in manufacture of calcium carbide required for manufacture of acetylene gas. Acetylene gas is the basic raw material for manufacture of acetic acid and P.V.C.
  3. It is used in manufacture of water gas and producer gas used as an important fuel.
    • Water gas is not single gas. It is a mixture of equal volumes of carbon monoxide and hydrogen.
    • Producer gas is produced by passing controlled amount of air over red hot coke. Producer gas is in fact a mixture of one part of carbon monoxide and two parts of nitrogen by volume.
  4. It is used to extract metals like copper, iron, zinc, lead, tin etc., from their ores.
  5. Since coke does not produce any smoke, hence it is used as a household fuel.

Question 8.
Explain the process of the formation of petroleum.
Answer:
Formation of Petroleum.
Petroleum is formed from the bacterial decomposition of the remains of animals and plants which got buried under the sea millions of years ago. When these organisms died, they sank to the bottom and got covered by sand and clay. Over a period of millions of years, these remains got converted into petroleum oil by heat, pressure and catalytic action. The hydrocarbons formed rose through porous rocks until they were trapped by impervious rocks forming an oil trap. Natural gas is found above the surface of petroleum oil.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 9.
The following table shows the total power shortage in India from 1991-1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.

S. No. Year Shortage %
1 1991 7.9
2 1992 7.8
3 1993 8.3
4 1994 7.4
5 1995 7.1
6 1996 9.2
7 1997 11.5

Answer:
PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum 1

PSEB Solutions for Class 8 Science Coal and Petroleum Important Questions and Answers

Multiple Choice Questions

Question 1.
Gurmeet’s mother uses cylinder to cook chapatti on gas burner at home. Name the gas in cylinder.
(a) Air
(b) Oxygen
(c) L.P.G.
(d) C.N.G.
Answer:
(c) L.P.G.

Question 2.
Monika read in a newspaper that a man became unconscious because of burning coal in a closed room. The teacher told her that during burning coal, a gas is produced which causes death of a person. Name
this gas.
(a) Oxygen
(b) Nitrogen
(c) Carbon-monoxide
(d) Hydrogen.
Answer:
(c) Carbon-monoxide.

Question 3.
The example of fossil fuel is:
(a) Air
(b) Sunlight
(c) Water
(d) Coal
Answer:
(d) Coal

Question 4.
Which out of the following is used as fuel in households ?
(a) Diesel
(b) Petrol
(c) Kerosene oil
(d) Bitumen.
Answer:
(c) Kerosene oil.

Question 5.
The purest form of carbon is:
(a) Coaltar
(b) Coal gas
(c) Diamond
(d) None of the above.
Answer:
(c) Diamond.

Question 6.
Which out of the following is the least pollution causing fuel ?
(a) Petrol
(b) Coal
(c) Kerosene oil
(d) C.N.G.
Answer:
(d) C.N.G.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 7.
Which is the natural solid fuel ?
(a) Coal
(b) Coke
(c) L.P.G.
(d) Coal tar
Answer:
(a) Coal.

Question 8.
Which among the following is the best domestic fuel ?
(a) Petrol
(b) Coal
(c) Kerosene oil
(d) C.N.G.
Answer:
(d) C.N.G.

Question 9.
Which of the following is the fossil fuel ?
(a) Air
(b) Hydrogen gas
(c) Water
(d) Coal.
Answer:
(d) Coal.

Question 10.
Which out of the following is the non renewable source of energy ?
(a) Air
(b) Sunlight
(c) Coal
(d) Forests
Answer:
(c) Coal

Question 11.
Which out of the following is called black gold ?
(a) Diesel
(b) Coal
(c) Bitumen
(d) Petroleum.
Answer:
(d) Petroleum.

Question 12.
Which out of the following is limited natural resource ?
(a) Air
(b) Sunlight
(c) Natural gas
(d) None of the above.
Answer:
(c) Natural gas.

Very Short Answer Type Questions

Question 1.
Name some natural materials.
Answer:
Air, water, soil, forests, minerals etc.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 2.
Name some man-made materials.
Answer:
Glass, cement, clothes, houses etc.

Question 3.
Define the term fossil fuel. Name three fossil fuels.
Answer:
Fossil fuels.
These are the fuels which are formed in nature from the dead remains of organisms over millions of years ago.
Examples. Coal, natural gas, petroleum etc.

Question 4.
How is coke prepared ?
Answer:
Coke is prepared by the destructive distillation of coal. The gases, and other substances present in coal are given off on heating. The black residue left behind is coke.

Question 5.
Name two products formed by Destructive distillation of Coal.
Answer:

  1. Coal gas
  2. Coal tar.

Question 6.
Name some products formed as a result of Fractional distillation of Petroleum.
Answer:
Asphalt, petrol, diesel oil, paraffin wax, fuel oil, kerosene oil.

Question 7.
Name three products of petroleum.
Answer:
Fertilizer, Insecticide, Artificial rubber.

Question 8.
What will happen if fossil fuels are used up at a fast rate ? Give reasons.
Answer:
Fossil fuel will get exhausted because the earth cannot recreate them rapidly.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 9.
Coal, petroleum, natural gas are example of which type of fuel ?
Answer:
Fossil fuel.

Question 10.
What is petroleum ?
Answer:
Petroleum. Petroleum is thick viscous crude oil with an unpleasant odour.

Question 11.
Which type of rocks store petroleum in them ?
Answer:
Impervious (non-porous) rocks.

Question 12.
Which process is used for refining petroleum ?
Answer:
Fractional distillation.

Question 13.
How is petroleum gas produced ?
Answer:
It is produced in the form of uncondensed gas during fractional distillation of crude petroleum oil.

Question 14.
What is the use of bitumen ?
Answer:
Road surfacing.

Question 15.
Which liquid fuel is used in stoves, lamps and jet air-crafts ?
Answer:
Kerosene oil.

Question 16.
Which product of petroleum is used for dry cleaning ?
Answer:
Petrol.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 17.
Name few exhaustible natural resources.
Answer:
Forests, wild life, minerals, coal etc.

Question 18.
Give examples of in-exhaustible natural resources.
Answer:
Air, water, sunlight etc.

Question 19.
Which natural material is available at a blacksmith’s place ?
Answer:
Coal.

Question 20.
What is main component of coal ?
Answer:
Carbon.

Question 21.
Which process converts dead vegetation into coal ?
Answer:
Carbonisation.

Question 22.
What happens when coal is heated or burn in air ?
Answer:
Carbondioxide gas is released.

Question 23.
Which condition is necessary for destructive distillation ?
Answer:
Absence of oxygen.

Question 24.
What is the latest use of coal-gas ?
Answer:
As a source of heat energy.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 25.
What is destructive distillation ?
Answer:
Destructive Distillation – The process of heating coal in the absence or limited supply of air is called destructive distillation.

Question 26.
What are hydrocarbons ?
Answer:
Hydrocarbons. The compounds of carbon and hydrogen are called Hydrocarbons.

Question 27.
What are Petrochemicals ?
Answer:
Petrochemicals.
These are the substances obtained from Petrol and Natural gas. These are largely used for the manufacture of detergents, synthetic fibres and plastics etc.

Short Answer Type Questions

Question 1.
Write two differences between Exhaustible and In-exhaustible Resources.
Answer:
Differences between Exhaustible and In-exhaustible Natural Resources.

Exhaustible Natural Resources In-exhaustible Natural Resources
1. Limited quantity in nature. 1. Limitless or unlimited quantity in nature.
2. Gets exhausted on consumption.

Examples: Forests, wild life.

2. Cannot exhaust on consumption i.e. can be retrieved back.

Examples: Air, Sun energy.

Question 2.
Where is petroleum found in India ?
Answer:
In India, petroleum is found in the states of Gujarat and Assam. It is also obtained from reservoirs buried deep under the sea bed near Mumbai. This oil-bearing region is called Bombay-High. Recently, oil has also been discovered in Godavari and Kaveri basins.

Question 3.
What are the major products of Petroleum refining ?
Answer:
During refining of petroleum following fractions are produced:

  1. Natural gas, Petrol,
  2. Naphtha,
  3. Kerosene oil,
  4. Gas oil (diesel),
  5. Lubricating oil/waxes,
  6. Fuel oil and
  7. Bitumen.

Question 4.
What are the products of coal ?
Answer:
Coal on heating in the absence of air gives coal gas, coal tar, and coke. Coal gas is also a good fuel. Coal tar gives important chemicals such as benzene, toluene, naphthalene, anthracene etc.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 5.
What is coal gas ? How is it formed ? Give its uses.
Answer:
Coal Gas. Coal gas is a mixture of methane, hydrogen and carbon monoxide.
When coal is heated in the absence of air, coal gas is formed.
Uses.

  1. It is used as a fuel.
  2. It is used for providing reducing atmosphere in metallurgical operations.

Question 6.
Give few uses of coal.
Answer:
Uses of Coal:

  1. As a fuel to cook food.
  2. To produce steam to run an engine.
  3. To produce electricity in Thermal Power plants.
  4. As a fuel in industry.

Question 7.
What is coal tar ? What are its uses ?
Answer:
Coal Tar. Coal tar is a black thick liquid with unpleasant smell. It is a mixture of about 200 substances, which are used as starting materials for the manufacturing of various daily need ithins such as paints, dyes, plastics, films, perfumes, explosives, drugs etc.
Coal tar is also used for road surfacing.

Question 8.
Name at least three constituents of petroleum and give their uses.
Answer:
Constituents of Petroleum

  1. Petrol
  2. Paraffin wax
  3. Diesel.

Uses of Petroleum:

  1. Petrol is used as a motor fuel and aviation fuel. It is also used for dry cleaning.
  2. Paraffin wax is used for making ointments, candles, vaseline etc.
  3. Diesel is used as a fuel for heavy motor vehicles and electric generators.

Question 9.
Define natural resource.
Answer:
Natural Resource. The resource that is obtained from nature is called natural resource.

Question 10.
What are the characteristics of a good fuel ?
Answer:
Characteristics of Good Fuel:

  1. It should be easily available.
  2. It should be cheap.
  3. It should be clean and should not produce poisonous gases and ash after burning.
  4. It should produce more energy.
  5. It should be easy to transport and store.

PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum

Question 11.
What is the difference between coal and coke ?
Answer:
Differences between Coal and Coke

Coal Coke
1. It is a non-crystalline form of carbon 1. It is an amorphous form of carbon.
2. It is obtained bj? death and decay of plants which remain buried under the earth for years together. 2. It is obtained by heating soft coal in the absence or limited siuply of air.

Long Answer Type Questions

Question 1.
What are fossil fuels ? How are they formed ? Why are they called non¬renewable sources of energy ?
Answer:
Petroleum, natural gas, coal etc., are main forms of fossil fuels. Millions of years ago, remains of animals, plants got buried under the earth before dinosaurs. These remains are called fossils. They remained inside the earth under huge pressure and high temperature in the absence of oxygen, these remains got converted into fossil fuel.

Fossils as a source of non-renewable source of energy.
Fossils were formed several hundred years ago under the earth. Man uses these for his various activities. These cannot be regained after use. So they are called non-renewable source of energy.

Question 2.
Describe the formation of
(a) Coal
(b) Petroleum.
Answer:
(a) Coal Formation.
Coal is believed to be formed from fossils which got buried inside the earth during earthquakes, volcanic eruptions etc., which occurred about 300 million years ago. These fossils were covered with sand, clay and water. In the absence of air and under high temperature and high pressure inside the earth, the fossils got converted into coal. This process of conversion of plants and animals buried inside the earth under high temperature and pressure to coal is called carbonisation. It is a very slow process and may have taken thousands of years.

(b) Formation of Petroleum.
It is believed that petroleum was formed and preserved in its crude state in the earth from the remains of dead microscopic marine plants (phytoplankton) which settled in muddy sediments at the bottom of sea millions of years ago. Prolonged sedimentation and cooking of these organic debris under pressure in the presence of natural catalysts, converted them into petroleum . For this reason, petroleum is also called fossil fuel.
PSEB 8th Class Science Solutions Chapter 5 Coal and Petroleum 2

Question 3.
What is petroleum? How does it occur? How is it mined?
Answer:
Petroleum.
It is dark coloured viscous, foul-smelling, oily liquid. It is a complex mixture of several solid, liquid, and gaseous hydrocarbons mixed with water, salt, and earth particles.

Occurrence of Petroleum.
Petroleum occurs deep down under the earth between two impervious rocks (non-porous rocks) as shown in Fig. Natural gas occurs above the petroleum oil trapped under rocks.

The crude petroleum is obtained by drilling a hole into the earth’s crust and sinking pipes into it. When the pipe reaches the oil deposit, natural gas comes out with great pressure. After the pressure has subsided, the crude oil is pumped out of the oil well. This process of obtaining crude oil from its sources is called mining.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Punjab State Board PSEB 8th Class Science Book Solutions Chapter 4 Materials: Metals and Non-Metals Textbook Exercise Questions and Answers.

PSEB Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals

PSEB 8th Class Science Guide Materials: Metals and Non-Metals Textbook Questions and Answers

Exercises

Question 1.
Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen.
Answer:
(a) Zinc.

Question 2.
Which of the following statements is correct?
(а) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.
Answer:
(a) All metals are ductile.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 3.
Fill in the blanks.
(a) Phosphorus is very ……………… non-metal.
(b) Metals are …………. conductor of heat and ……………… .
(c) Iron is ……………… reactive than copper.
(d) Metals react with acids to produce ……………………. gas.
Answer:
(a) reactive.
(b) good, electricity.
(c) more.
(d) Hydrogen.

Question 4.
Mark ‘T’ if the statement is true and ‘F’ if it is false.
(а) Generally, non-metals react with acids.
(b) Sodium is a very reactive metal.
(c) Copper displaces zinc from zinc sulphate solution.
(d) Coal can be drawn into wires.
Answer:
(a) True
(b) True
(c) False
(d) False

Question 5.
Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties. (From Board M.Q.P.)

Properties Metals Non-metals
1. Appearance
2. Hardness
3. Malleability
4. Ductility
5. Heat Conduction
6. Conduction of electricity

Answer:
Differences between metals and non-metals.

Properties Metals Non-metals
1. Appearance Silvery or grey in colour. Different coloured non-metals.
2. Hardness Solid at room temperature. Solid, liquid or gas at room temperature and brittle.
3. Malleability Can be beaten into sheets. Non-malleable.
4. Ductility Can be drawn into wires. Non-ductile.
5. Heat Conduction Present. Absent.
6. Conduction of electricity Possible. Not Possible.

Question 6.
Give reasons for the following :
(a) Aluminium foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
(c) Copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene.
Answer:
(a) Aluminium foils are used to wrap food items because aluminium is malleable and less reactive to air and water.

(b) Immersion rods for heating liquids are made of metallic substances because metals are good conductors of heat and electricity.

(c) Copper is less reactive than zinc. As a result it cannot replace zinc from its salt solution.

(d) Sodium and potassium are very reactive metals. They react with air and water to form respective oxides and hydroxides. So, they are kept in kerosene.

Question 7.
Can you store lemon pickle in aluminium utensil ? Explain.
Answer:
No. Lemon pickle cannot be stored in aluminium utensils because acid present in lemon pickle reacts with aluminium to produce poisonous chemicals, which can cause food poisoning or other health hazards.

Question 8.
Match the substances given in Column A with their uses given in Column B.

Column A Column B
(i) Gold (a) Thermometers
(ii) Iron (b) Electric wire
(iii) Aluminium (c) Wrapping food
(iv) Carbon (d) Jewellery
(v) Copper (e) Machinery
(vi) Mercury (f) Fuel

Answer:

Column A Column B
(i) Gold (d) Jewellery
(ii) Iron (e) Machinery
(iii) Aluminium (c) Wrapping food
(iv) Carbon (f) Fuel
(v) Copper (b) Electric wire
(vi) Mercury (a) Thermometers.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 9.
What happens when
(a) Sulphuric acid is poured on a copper plate ?
(b) Iron nails are placed in copper sulphate solution ?
Write word equations of the reactions involved. (From Board M.Q.P.)
Answer:
(a) When sulphuric acid is poured on copper plate, Hydrogen gas is given out.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 1

(b) When iron nails are placed in copper sulphate solution, iron displaces copper from its salt to form iron sulphate
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 2

Question 10.
Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(а) How will she find the nature of the gas ?
(b) Write down word equations of all the reactions taking place in this process.
Answer:
(a) To test the nature of the gas:
1. Take blue/red litmus solution turnwise into the jar of gas collected. It will turn blue litmus red while red litmus will remain unaffected. This shows that gas is acidic in nature.
2. Add some water to the jar. The liquid for turns blue litmus red showing acidic nature of the gas.

(b) When a charcoal is burnt, it reacts with oxygen to form an acidic oxide called
carbon dioxide.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 3

The acidic oxide, carbondioxide, dissolves in water to form an acid called Carbonic acid
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 4

Question 11.
One day Reeta went to a jeweller’s shop with her mother. Her mother gave an old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight ?
Answer:
Jewellers usually use a chemical solution named aquaregia for cleansing the jewellery. This solution is capable of dissolving gold in it. So, loss in weight is found.

Multiple Choice Questions

Question 1.
In order to keep the flow of electricity continue in circuit, which of the following items should be used in place of iron nail in the given circuit. (From Board M.Q.P.)
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 5
(a) Graphite
(b) Plastic
(c) Wood
(d) Rubber.
Answer:
(a) Graphite.

Question 2.
Sodium metal is stored ………………….
(a) In water
(b) In kerosene oil
(c) In Air
(d) None of these.
Answer:
(b) In kerosene oil.

Question 3.
When strip of iron is placed in moist air then after some days a layer is deposited over it which has colour:
(a) Green
(b) Red
(c) Dirty
(d) None of these.
Answer:
(b) Red.

Question 4.
Which of the following statements is correct ?
(a) All metals are ductile
(b) All non-metals are ductile.
(c) Generally metals are ductile
(d) Some non-metals are ductile.
Answer:
(c) Generally metals are ductile.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 5.
Which of the following is a non-metal ?
(a) Iron
(b) Carbon.
(c) Gold
(d) Calcium.
Answer:
(b) Carbon.

Question 6.
Phosphorus is stored in:
(a) Water
(b) Air
(c) Oil
(d) None of the above.
Answer:
(a) Water

Question 7.
The metal which is found in liquid form is:
(a) Copper
(b) Silver
(c) Mercury
(d) Sodium.
Answer:
(c) Mercury.

Question 8.
Which metal is a good conductor of electricity and heat ?
(a) Sodium
(b) Potassium
(c) Copper
(d) None of the above.
Answer:
(c) Copper.

Question 9.
The best conductor of electricity is:
(a) Copper
(b) Lead
(c) Aluminium
(d) Silver.
Answer:
(d) Silver

Question 10.
Red colour makes the solution of litmus blue because of:
(a) Metal oxide
(b) Sulphur dioxide
(c) Carbondioxide i
(d) None of the above.
Answer:
(a) Metal oxide.

Question 11.
Non-metal on the base of hardness is:
(a) Iron
(b) Aluminium
(c) Copper
(d) Coal.
Answer:
(d) Coal.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 12.
Which of the following gas is released when a metal react with acids ?
(a) Oxygen
(b) Hydrogen
(c) Sulphur dioxide
(d) Nitrogen
Answer:
(b) Hydrogen.

Very Short Answer Type Questions

Question 1.
Name the property because of which metals can be beaten into thin layers or sheets.
Answer:
Malleability.

Question 2.
What is ductility ?
Answer:
Ductility. The property by which metals can be drawn into wires, is called ductility.

Question 3.
Name the most ductile metal.
Answer:
Silver.

Question 4.
Name the metal which exists in the liquid state.
Answer:
Mercury.

Question 5.
Name one metal which is poor conductor of electricity.
Answer:
Lead.

Question 6.
Which metal is used in thermometer ?
Answer:
Mercury.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 7.
Which metal and non-metal is liquid at ordinary temperature ?
Answer:
Metal – Mercury
Non-Metal – Bromine.

Question 8.
Write two properties of metals.
Answer:
Malleability and Ductility.

Question 9.
Name two metals which are good conductors of both heat and electricity.
Answer:
Copper and Aluminium are good conductors of both heat and electricity.

Question 10.
Name three metals which occur in the native state.
Answer:

  1. Silver
  2. Gold
  3. Platinum occur in the native state.

Question 11.
List two metals which are easy to cut.
Answer:

  1. Sodium
  2. Potassium.

Question 12.
What is that property, which allows metals to be drawn into wires, called ?
Answer:
Ductility.

Question 13.
Which metals are used to make electric wires ?
Answer:
Copper and Aluminium.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 14.
Which metal is constituent of haemoglobin ?
Answer:
Iron.

Question 15.
Write a chemical reaction of Iron with Oxygen.
Answer:
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 6

Question 16.
Write the chemical equation for the reaction of Zn with Oxygen.
Answer:
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 7

Question 17.
The set of metals in order of their increasing chemical reactivity is given below:
Silver, copper, lead, iron, zinc, magnesium and sodium.
(a) Which of the above metals is stored in kerosene ?
(b) Which metals will react with cold water ?
(c) Which gas will be liberated when metals react with cold water ?
(d) Which of the metals will react with oxygen when heated ?
(e) Which of the metals becomes black in the presence of hydrogen sulphide, H2S ?
(f) Which of the metals burns with white bright flame in oxygen ?
Answer:
(a) Sodium
(b) Sodium and Magnesium
(c) Hydrogen
(d) Magnesium
(e) Silver
(f) Magnesium.

Question 18.
Name five metals which are used in daily life.
Answer:
Metals used in daily life.

  1. Aluminium
  2. Iron
  3. Copper
  4. Zinc
  5. Tin.

Question 19.
Name five metals which are used in our industrial processes.
Answer:
Metals used in Industrial Processes.

  1. Aluminium
  2. Iron
  3. Copper
  4. Nickel
  5. Zinc.

Question 20.
Why do Sodium, Zinc, Magnesium and Aluminium not occur in their pure state ?
Answer:
Because these react with air, water and acids.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 21.
Name atleast two metals which do not react with air, water and acids.
Answer:

  1. Gold
  2. Platinum.

Question 22.
Of what property, are metals used in jewellery ?
Answer:
Metallic lustre.

Question 23.
What is the colour of copper metal ?
Answer:
Eeddish-brown colour.

Question 24.
Of Iron, Copper and Magnesium, which metal can be cut easily ?
Answer:
Magnesium.

Short Answer Type Questions

Question 1.
What is the difference between a metal and a non-metal ? What is the total number of naturally occurring elements ?
Answer:
Metals have metallic lustre, are malleable, ductile, good conductors of heat and electricity, hard and combine with oxygen to form basic oxides.

Non-metals have dull lustre, not malleable and non-ductile, bad conductors of heat and electricity, brittle and combine with oxygen to form acidic oxides. The total number of naturally occurring elements is 92.

Question 2.
Why is Potassium metal not stored in water ?
Answer:
Potassium is a reactive metal. It reacts with air even at room temperature. Also it reacts with water at room temperature and catches fire. Hence, it is not stored in water but kept under kerosene oil.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 8

Question 3.
State two physical properties on the basis of which metals may be distinguished from non-metals.
Answer:

  1. Metals are good conductors of heat and electricity. Non-metals are bad conductors of heat and electricity.
  2. Metals have a shiny appearance, that is, they show a metallic lustre. Nonmetals have a dull lusture. They generally do not reflect light well.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 4.
State one chemical property which may be used to distinguish a metal from a non-metal.
Answer:
Metals when burn, combine with oxygen to form metallic oxides which are basic in nature, whereas non-metals combine with oxygen to form acidic oxides. This property can be used to distinguish a metal from a non-metal.

Question 5.
Why is sodium stored in kerosene oil ?
Answer:
Sodium is highly reactive metal. It readily combines with oxygen when exposed to air and sometimes it even catches fire. It also reacts with water forming its hydroxide. To prevent its oxidation, sodium is stored under kerosene oil.

Question 6.
Explain the following:
(а) Acidic oxides
(b) Basic oxides.
Answer:
(a) Acidic Oxides. These are the oxides of non-metals and give acids when dissolved in water.
Examples : CO2, SO2 etc.

(b) Basic Oxides. These are the oxides of metals and give alkaline or basic solutions in water.
Examples : Sodium oxide, Calcium oxide etc.

Question 7.
Explain the occurrence of metals in nature.
Answer:
Occurrence of Metals in Nature. Metals occur in the nature in free as well as in combined state.
1. Free or Native State. The metals which are not attacked by air and moisture generally occur in the free or native state e.g. metals like gold, platinum etc.

2. Combined State. Metals generally occur in nature in the form of compounds
such as oxides, sulphides etc. These metals are said to occur in the combined state, e.g. Aluminium oxide.

Question 8.
What do you understand by ductility and malleability of a metal ? Give examples of two metals which are both ductile and malleable.
Answer:
Ductility.
It is the property of metals by virtue of which metals can be drawn into thin unbroken wires. Metals exhibiting this property are called ductile.
Examples : Copper, Aluminium, Silver, Gold.

Malleability. It is the property of metals by virtue of which Metals which can be beaten into thin sheets and twisted or bent without breaking. Metals showing this property are called malleable.
Examples : Gold, Silver, Aluminium.
Examples of two metals which are both malleable and ductile :
Aluminium and Gold.

Question 9.
Silver does not combine easily with oxygen but silver jewellery tarnishes after some time. How ?
Answer:
Silver does not combine easily with oxygen of the air. But it readily combines with sulphur compounds such as hydrogen sulphide present in the air to form a black coating of silver sulphide. Therefore, silver jewellery tarnishes after some time.

Question 10.
Why do gold ornaments look new even after several years of use ?
Answer:
Gold does not tarnish. That is, it never corrodes as it is non-reactive. It is unaffected by air, water and acids. This is why gold ornaments look new even after several years of use.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 11.
Magnesium and copper metals are heated directly over a flame. Which of these will burn in air ? Which is more reactive ?
Answer:
When magnesium and copper are heated directly over a flame, magnesium will burn in air. Magnesium is more reactive.

Question 12.
CuSO4 + Fe → FeSO4 + Cu
FeSO4 + Zn → ZnSO4 + Fe
On the basis of the above reactions, indicate which is the most reactive and which is the least reactive metal out of zinc, copper and iron ?
Answer:
In the first reaction, iron displaces copper from copper sulphate solution, therefore, iron is more reactive than copper. In the second reaction zinc displaces iron from iron sulphate, therefore, zinc is more reactive than iron. Therefore, zinc is the most reactive metal while copper is the least reactive.

Question 13.
Why are pickles, chutney and citrus fruits not stored in iron and aluminium utensils ?
Answer:
Certain foodstuffs, particularly citrus fruits, chutney, pickles and curd, which contain acids tend to attack kitchen utensils made of aluminium and iron forming poisonous salts. Iron and aluminium utensils are, therefore, not used to store pickles, chutney and citrus fruits.

Question 14.
What would you observe when a strip of zinc is dipped in the solution of copper sulphate ?
Answer:
Zinc being more reactive would replace copper from its salt solution i.e. copper sulphate.
Zn + CuSO4 → ZnSO4 + Cu

Question 15.
Can copper displace iron from iron sulphate solution ? Give reasons.
Answer:
No, because copper is less reactive than iron. As a result, it can’t replace iron from its salt solution i.e. iron sulphate. Only more reactive metals can replace less reactive metals from their salt solutions. Vice-versa is not possible i.e., less reactive metals cannot replace more reactive metals from their salt solutions.

Question 16.
Why does aluminium vassel lose its lusture after sometime ?
Answer:
Aluminium is a reactive metal. During its use, it comes in contact with air and water when it forms dull coating of aluminium oxide on its surface. Hence the vessel loses its shine.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 17.
Why aluminium metal is preferred to copper for making cooking utensils ? Give two reasons.
Answer:
Because of the following two reasons, aluminium is preferred to copper for making cooking utensils.

  1. It is very light and is a good conductor of heat.
  2. It is not readily attacked by acids present in the food materials to be cooked.

Question 18.
What is corrosion ? What are the different ways to reduce corrosion ?
Answer:
Corrosion. Metals when exposed to moist air get covered with dull layer.
This layer can be easily removed giving place to the next such layer to be formed. In this way, metal is eaten up or corroded and the process is called corrosion.
Ways to reduce corrosion:

  1. By covering the metal with paint
  2. By applying oil or grease on the surface of metal.
  3. By coating the metal with some other metal which is not easily corroded by passing electricity.
  4. By making an alloy.

Question 19.
Sodium occurs in the combined state where as Gold in its native state, why ?
Answer:
Sodium is the most reactive metal. It readily combines with air and water to form its compounds. So it occurs as compound. On the other hand Gold is the noble metal and is not attacked by air, water or acids so it exists in its native form.

Question 20.
Does copper rust ? What will happen if copper is exposed to moist air ?
Answer:
Copper does not rust. When copper is exposed to moist air for long, it acquires a dull green coating. The green material so formed is a mixture of Copper hydroxide [CU(OH)2] and Copper carbonate [CuCO3], The following reaction takes place:
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 9

Question 21.
Give reasons for the following:
(i) Aluminium is used in making parts of aeroplane.
(ii) Copper is used in making electric wires.
(iii) Silver is used in making mirrors.
(iv) Graphite is used as an electrode in the Dry cell.
(v) Iron is used in constructing bridges and dams.
Answer:
(i) Aluminium being light and strong metal is used in making parts of aeroplanes.
(ii) Copper is a good conductor of electricity. So, it is used for making electric wires.
(iii) Silver is very shining white metal and has, therefore, high reflecting power.
(iv) Graphite is a good conductor, so it used for making electrode in dry cells.
(v) Iron being strong and rigid metal is used in the construction of bridges and dams.

PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Long Answer Type Questions

Question 1.
Give general physical properties of metals.
Answer:
General physical properties of metals:

  1. Metals have a shiny appearance, i.e. they show metallic lustre.
  2. Metals are generally hard and their hardness varies from metal to metal.
  3. Most metals are malleable, i.e. they can be hammered into thin sheets.
  4. Metals are ductile and, therefore, can be drawn into wires.
  5. Metals are good conductors of heat and electricity. Electricity flows most readily through gold, silver, copper and aluminium.
  6. Metals are generally sonorous i.e. metals make sound when hit with an object.
  7. All metals except mercury exist in solid form at room temperature.
  8. Metals have high melting points.

Question 2.
Give general physical properties of non-metals.
Answer:
General physical properties of non-metals:

  1. Lustre. Non-metals possess dull lustre, i.e., they do not reflect light well. Exceptions are graphite and diamond.
  2. Conductivity. Non-metals are poor conductors of heat and electricity. Exception is graphite.
  3. State. Non-metals may occur as solids or liquids or gases at room temperature. For example Sulphur, Carbon and Iodine are solids. Bromine is a liquid. Chlorine and nitrogen are gases.
  4. Malleability. Non-metals are not malleable but they are brittle. Non-metals break into small pieces when hammered.
  5. Hardness. Non-metals are generally not hard but diamond is exception. Diamond is the hardest known substance.
  6. Ductility. Non-metals cannot be drawn into wires and are, therefore, not ductile
  7. Melting and Boiling Point. Non-metals have low melting and boiling points. A majority of non-metals are gases. Exception is graphite which has a high melting point.

Question 3.
How do metals react with acids ?
Answer:
Reaction of metals with acids :
1. Active metals like zinc, magnesium, iron etc. which lie above hydrogen in the electrochemical series or activity series can displace hydrogen from dilute mineral acids such as hydrochloric acid and sulphuric acid.
PSEB 8th Class Science Solutions Chapter 4 Materials Metals and Non-Metals 10

2. The metals which lie below hydrogen don’t displace hydrogen from dilute mineral acids such as hydrochloric acid, sulphuric acid etc.
For example, copper does not react with dil. HCl.

Question 4.
How do metals react with water ?
Answer:
Reaction of metals with water. Different metals have different reactivities with water. All metals react with water under different conditions to produce hydrogen gas.
1. Active metals like Na, K react with water at room temperature.
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The reaction is so violent and exothermic that the evolved hydrogen catches fire.

2. Less active metals like Mg, Zn, Al, react with boiling water.
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3. Metals like Fe, Ni react very mildly with steam
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PSEB 8th Class Science Solutions Chapter 4 Materials: Metals and Non-Metals

Question 5.
Which of the following displacement reaction cannot occur ?
(a) CUSO4(aq) + Fe → FeSO4(aq) + Cu
(b) FeSO4(aq) + Zn → ZnSO4(aq) + Fe
(c) ZnSO4(aq) + Pb → PbSO4(aq) + Zn
(d) 2AgNO3(aq) + Cu → Cu(NO3)2 + 2Ag
(e) MgSO4(aq) + Cu → CuSO4 + Mg
Answer:
A more reactive metal (placed higher in the activity series) can displace the less reactive metal from its solution. Out of the above five reactions.
(c) cannot occur because zinc is more reactive than lead.
(e) cannot occur because magnesuim is more reactive than copper.

Question 6.
Name three metals that you come across in your daily life and also give their uses.
Answer:
We come across directly or indirectly the following metals in our daily life:

  1. Iron
  2. Copper
  3. Aluminium

1. Uses of Iron :

  • Iron mixed with other metals is largely used in making trains, automobiles and other machine parts.
  • Iron mixed with cement is used in constructing big buildings and dams.
  • Iron is used in making bridges and boilers for industry.

2. Uses of Copper:

  • It is used for making cooking utensils,
  • It is used in making photoframes, coins and statues.
  • It is used for making electrical wires.

3. Uses of Aluminium:

  • It is used for making aeroplanes
  • It is used for making electric wires and parts of electric gadgets.
  • Aluminium foils are used as packing material.

Question 7.
Distinguish between metals and non-metals on the basis of their chemical properties.
Answer:
Distinction between Metals and Non-metals

Property Metals Non-Metals
Chemical Properties-

1. Nature of Ions

Metals are electr-opositive elements and lose electrons to become electro-positive ions. Non-metals are electro-negative elements and gain electrons to form negative ions.
2. Nature of Oxides Form basic oxides Form acidic oxides.
3. Reaction with Water Mostly displace hydrogen. Do not react with water.
4. Reaction with Acids Metals above hydrogen in the activity series displace hydrogen from Non-metals do not react with dilute acids.
5. Nature of Hydrides Metals react with hydrogen to form ionic hydrides. Form covalent hydrides.
6. Nature of Chlorides Metals combine with chlorine to form solid ionic chlorides which conduct electricity. Non-metals combine with chlorine to form covalent chlorides which do not conduct electricity.

Question 8.
Give general chemical properties of non-metals.
Answer:
1. Reaction with Air or Oxygen. Non-metals react with air or oxygen to form their corresponding oxides which are acidic in nature. These oxides turn blue litmus red.
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2. Reaction with Hydrogen. Non-metals like carbon, Nitrogen, and Phosphorous react with Hydrogen to form different compounds.
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3. Reaction with other non-metals. Non-metals react with other non-metals to form compounds
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4. Reaction with Acids. Non-metals react with acids to form corresponding oxyacids.
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