Class 10

Punjab State Board PSEB 10th Class Science Important Questions Chapter 4 Carbon and its Compounds Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 4 Carbon and its Compounds

Long Answer Type Questions

Question 1.
What is allotropy? Name the allotropes of carbon. Are they chemically same? Compare their physical properties.
Answer:
Allotropy: The phenomenon of existence of two or more different physical forms of the same chemical element, with same chemical properties is called allotropy.

Allotropes of carbon

• Diamond
• Graphite

Similarity in chemical composition:
If both the allotropes in equal amount are heated in air then both will release same amount of carbon dioxide and will not leave any residue. Therefore this proves that both are same in chemical composition.

Comparison of Physical Properties

Property	Diamond	Graphite
1. Appearance	Transparent	Black, shiny
2. Hardness	Very hard	Soft, slippery/ smooth in touch
3. Heat conductivity	Very less	Medium conductor
4. Electric conductivity	Bad conductor	Good conductor
5. Density (kg/m3)	3 – 510	2 – 250
6. Purity	Purest	Less pure than diamond
7. Melting point	3500°C	3000°C
8. Uses/Applications	Jewellery, drilling purpose Lubricants.	Drycells, Electric Arcs, Pencils, Lead,

Question 2.
What is covalent bond? Write its properties.
Answer:
The chemical bond formed by sharing of electrons between atoms of same or different non-metal elements is known as covalent bond.

Properties of Covalent bond/bonds.

• They hax e strong bonds within molecules but their inter molecular bond is weak.
• They have low boiling points.
• They have low melting points.
• Their compounds are bad conductors of electricity.

Question 3.
(a) Why does carbon form largest number of compounds?
Answer:
This is due to its tetracovalency and catenation.

(b) Why are some of these called saturated and other unsaturated compounds?
Answer:
The compounds containing C – C single bond are called saturated compounds and the compound containing

bonds are called unsaturated compounds.

(c) Which of these two is more reactive?
Answer:
Unsaturated compounds are more reactive than saturated compounds.

(d) Write the names of the compounds
(i) CH₃ – CH₂ – Br
Answer:

Answer:

Question 4.
Write about nomenclature of carbon compounds.
Answer:
The names of compounds in a homologous series are based on the name of basic carbon chain modified by a prefix’ ‘phrase before’ or ‘suffix’ ‘phrase after’ indicating the nature of the functional group. For example, the names of various alcohols are methanol, ethanol, propanol and butanol.

Naming of carbon compound can be done by the following method :

• Identify the number of carbon atoms in the compound. A compound having three carbon atoms will have the name propane.
• In case a functional group is present, it is indicated in the name of the compound with either a ‘prefix’ or a ‘suffix’. Like chloro propane, bromo propane, propanal, propanone etc.
• If the name of functional group is to be given on the basis of suffix, the name of the carbon chain is modified by deleting the final ‘e’ and adding the appropriate suffix. For example, a chain having three carbons with a Ketone group will be given name in the following manner.
  Propane-‘e’ = propan + ‘one’ = propanone.
• If the carbon chain is unsaturated then the final ‘ane’ in the name of carbon chain is substituted by ‘ene’ or ‘yne’. For example, a three-carbon chain with a double bond would be called propene and if it has triple bond, it would be called propyne.

Question 5.
Write down the chemical properties of carbon compounds.
Answer:
The main chemical properties of carbon compounds are :
1. Burning: Carbons in all its allotropic forms burns in the presence of oxygen and produces heat, light and C02, For example :
C + O₂ → CO₂ + heat and light
CH₄ + 2O₂ → CO₂ + 2H₂O + Heat and light
CH₃CH₂OH + 3O₂ → 2CO₂ + 3H₂O + Heat and light.
Saturated hydrocarbons burn with a clear flame whereas unsaturated hydrocarbons burn with sooty yellow flame.

2. Oxidation: Carbon compounds can easily be oxidised by burning. Alkaline potassium permanganate or acidified potassium permanganate converts alcohols into acids.

3. Addition reaction: Unsaturated hydrocarbons make saturated hydrocarbons by adding hydrogen to itself in the presence of catalysts like nickel and palladium. The reaction is commonly used in hydrogenation of vegetable oils using nickel catalyst.

Vegetable oils generally have long unsaturated carbon chain while animal fats have saturated carbon chains.

4. Substitution reaction: Saturated hydrocarbons are fairly unreactive and are inert in the presence of most reagents. However, in the presence of sunlight, chlorine gets combined with hydrocarbons in a quick reaction. Chlorine replaces very quickly the hydrogen atoms in the chemical reaction one by one due to which number of products are usually formed with the higher homologous of alkanes.

Question 6.
(a) What is an alcohol? Give two examples.
Answer:
Alcohol is a simple compound of carbon, hydrogen and oxygen. If one hydrogen atom is replaced by hydroxyl (-OH) group in alkene, alcohol is produced. General formula of alcohol is C_nH_2n+2

Examples :

• In Methane (CH₄) when hydrogen atom is replaced by hydroxyl (- OH) group, methanol (CH₃OH) is formed.
• Ethanol (C₂H₅OH) is produced with the help of ethane

(b) How is synthetic ethanol produced? Also write.
Answer:
Synthetic ethanol is prepared by reacting ethane with water in the presence of phosphoric acid (H3P04).

Properties of Ethanol :

• It is a colourless liquid with specific colour.
• Its boiling point is 351 K and melting point is 156 K.
• It is soluble in water in any proportion.
• It doesn’t show any reaction with litmus because it is neutral.
• It burns with blue flame in air to produce carbon dioxide and water.
  C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
• It reacts with oxygen or potassium dichromate (K₂Cr₂O₇) to produce ethanoic acid.
  C₂H₅OH + O₂ → CH₃COOH + H₂O
• It reacts with sodium metal.
  2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂
• It reacts with acetic acid in the presence of concentrated H₂SO₄. When this mixture is heated and poured in ice cold solution of sodium carbonate, a sweet smell is produced.

Question 7.
Give important properties of monocarboxylic acids. Also give its uses.
Or
Give important properties of ethanoic acid (Acetic acid). Also give its uses.
Answer:
Important properties of monocarboxylic acid :
1. Ethanoic acid or acetic acid is colourless liquid and is soluble in water, 5-8% solution of acetic acid in water is called vinegar.

2. Pure ethanoic acid melts at 290 K and freezes during winter in cold climates and looks like ice. Hence it is called glacial acetic acid.

3. Esterification: When an acid is heated with an alcohol in the presence of cone. H2S04, an ester is produced. This is a slow reversible reaction and is called esterification.

Esters are sweet-smelling substances.

4. Action with a base

5. Action with carbonates and bicarbonates
Ethanoic acid decomposes carbonates and bicarbonates producing salt, carbon dioxide and water.
2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂ ↑
CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂ ↑

Uses of ethanoic acid :

• It is used in the manufacture of dyes, perfumes and rayon.
• It is used in the manufacture of plastics, rubber and silk industries.
• It is used as a solvent.
• It is used as a vinegar in cooking, as food dressing and for preparing pickles.
• It is used for the manufacture of chemicals like acetone, acetic anhydride, etc.
• It is used for making white lead [2PbCO₃. Pb(OH)₂]

Question 8.
Explain the following terms :
(i) Esterification
Answer:
Alcohols are treated with carboxylic acids in the presence of concentrated sulphuric acid to form ester and this process in known as esterification.

Method: Mix ethyl alcohol with acetic acid in a test tube. Few drops of concentrated sulphuric acid is added and test tube is heated mildly in hot tub of water. Instantaneously sweet smell of ester is diffused in whole room.

It is an example of esterification. Ester is used in ice-cream, cold drinks, medicines, make up etc.

(ii) Saponification
Answer:
Saponification: Breaking down of fats is called saponification.

It is performed by heating vegetable or animal oils with 40% solution of caustic soda. Fats and base react to produce soap and glycerol.

Concentrated common salt solution is added to crystallize soap from water. Soap floats on the surface of water, after cooling. Soap is extracted from water and desired colour and smell are added and is given desired shape.

(iii) Decarboxylation
Answer:
Decarboxylation: Methane is produced when sodium or potassium salt of ethanoic acid are heated with sodium hydroxide and calcium oxide in 3 : 1 ratio.

It is a useful method to prepare methane. It is known as decarboxylation because one molecule of CO₂ is removed.

(iv) Polymerization.
Answer:
Polymerization: When a large number of small molecules join together at a specific temperature and pressure to form a big molecule, this process is termed as polymerization. These small molecules are known as ‘monomer’ whereas big combined molecule is known as ‘polymer.’
For example. Molecules of ethene join together at 2000 atm pressure and 200°C to form polythene.

Question 9.
Describe a method for the preparation of soap.
Answer:
Soaps are sodium or potassium salts of higher fatty acids. When the naturally occurring esters called fats or oils are heated with NaOH solution, they undergo hydrolysis to form sodium salt of higher fatty acid (called soap) and glycerol.

Manufacture of Soap. Soap can be made easily in the laboratory. Heat fat or oil with sodium hydroxide solution. After a few minutes, and constant stirring, the oil and water layers get mixed.

Add 5-10 g of common salt to it, stir the mixture and allow’ it to cool. On cooling, pale yellow a solid forms as a cake called soap.

The same principle is used for making soap in soap industry. Some other substances like perfumes, disinfectants and medicines are added to soap to give it desired characteristics.

Example :

Question 10.
What do you understand by isomers? Explain it with an example.
Or
Write down the isomers of butane.
Answer:
Isomers. The compounds with same molecular formula but different structural formula are called isomers and the phenomenon is called isomerism. There is no change in the structure of methane, ethane, propane if the atoms of carbon and hydrogen are rearranged but in case of alkane molecule if number of carbon is more than three then more than one arrangement is possible.

In this one long carbon chain is formed and the others are branched. In case of butane the chain is linked with atleast three carbon atoms with other carbon atoms. This type of alkanes are termed as iso-alkane. In a chain having no branch, carbon atom cannot be linked with two carbon atoms. Alkanes of this type are called normal alkane (n-alkane).

Two Isomers of Butane:

Isomers of Pentane

Short Answer Type Questions

Question 1.
Explain why carbon forms mostly covalent compounds?
Answer:
Carbon has four electrons in its outermost shell. In order to get stable electronic configuration, it has to lose or gain four electrons, but it is difficult to lose or gain four electrons from energy considerations. Hence, Carbon complete its octet by sharing its valence electrons with other atoms forming covatent bonds resulting in the formation of covalent compounds.

Question 2.
In order to form large amount of carbonic compounds which major elements are used other than hydrogen and oxygen?
Answer:
The number of carbonic compounds is very large which was not possible only with the help of hydrogen and oxygen. Along with these two elements some other elements like nitrogen, sulphur, oxygen, halogens (Cl, Br, I, F) etc. also combine and because of it the caybonic compounds have crossed the number of many million. These combine together on the basis of functional groups and make new compounds.

Question 3.
‘Carbon is a unique element’, why?
Answer:
Carbon is the only known element out of all other known elements, that has got capability to make long chains. Each long chain of carbon atoms provides such a simple base with which other atoms can join by various methods resulting in the composition of various compounds.

Carbon atoms can make long chains or rings in three ways because of having catenation property.

Question 4.
Explain the structure of diamond and write why is it so hard?
Answer:
In diamond each carbon atom remains at the centre of regular tetrahedral and it remains bound with covalent bond to four carbon atoms which are situated at four corners of tetrahedral. Thus, all electrons of carbon are bound atoms and none is found in free state. So it forms a strong three-dimensional tetrahedral structure and because of it diamond is the hardest substance with very high density.

Question 5.
What are the uses of diamond?
Answer:
Uses of Diamond

• Diamond being the hardest substance is used for cutting other substances.
• Diamond because of its shine and lustre is used for making ornaments.
• It is used for drilling hard rocks.
• Sharp-edged diamonds are used by eye surgeon in catract surgery.
• Being extra ordinarly sensitive for heat radiations and having property to remove immediately harmful radiations. These are used in making absolute thermometers.

Question 6.
Why do diamonds glitter?
Answer:
Diamond is a transparent substance whose refractive index is very high. The rays of light passing through it get diverted much. According to its cut base edges light rays undergo total internal reflection. When these edges are polished, diamond glitters very beautifully.

Question 7.
How are diamonds made naturally and artifically?
Answer:
Naturally, diamonds are made by carbon present at the depth of about 150 km, where pressure is 70,000 atm and the temperature is about 1500°C. These diamonds come up near the surface with special kimberlite rocks. Artifically, diamonds are made by heating graphite under high pressure in the presence of special catalysts.

Question 8.
Write the structure of graphite. Why is it so soft?
Answer:
Each carbon atom is bonded with three neighbouring carbon atoms with covalent bonds in graphite. They are always in the same plane giving hexagonal array. As compared to diamond, the distance between carbon atoms is more. The distance between upper and lower layers does not permit carbon atoms to make covalent bonds and because of this fourth electrons remains free. These layers can easily slide one upon the other and graphite attains the property of a lubricant. It is very soft and slippery.

Question 9.
Why are diamonds used in jewellery? Give reasons.
Answer:
Refractive index of diamond is 2.45 which is the highest of all known substances, because of this, it shines brightly. Its critical angle is 24°, which is very less. This is why, the light rays passing through it deviates much. A small deviation in it causes beautiful spectrum of colours. When the bases of diamond are polished, it produces an astonishing brightness. That is why diamonds are used in making jewellery.

Question 10.
Why is graphite a good conductor of electricity?
Answer:
Each carbon atom of graphite is surrounded by three carbon atoms joined with covalent bond which makes hexagonal layers over each other. In these layers distance between the carbon atoms is more, that is why the possibility of fourth covalent bond between the carbon atoms of opposite layers is reduced. The fourth covalent electron is set free. The graphite has easy flow of electrons and it acts as a good conductor of electricity.

Question 11.
What are the uses of graphite?
Answer:
Uses of Graphite

• It is good conductor of electricity so- it is used in making dry cells and electric arcs as electrods.
• It is used in making pencils, black colour and black paint.
• It has lubricant property so it is used in machines to keep them lubricating at high temperature.
• It is used in making crucibles to boil some metals because of its high melting point.

Question 12.
Why are allotropes of carbon in form a molecule known as fullerenes?
Answer:
The allotropes of carbon in which 60 carbon atoms join to form a molecule are termed as fullerene. US architect Buckminster Fuller designed three dimensional domes which were supported by pentagonal and hexagonal structures.

Since fullerene molecules looked like these domes, that is why they are known as fullerene.

Question 13.
Draw the electron dot structures of methane, ethane, ethene, butane.
Or
(i) Write molecular formula of butane.
(ii) Draw the structure of Propanal.
Answer:
Methane
Formula -CH₄

Ethane
Formula -C₂H₆

Ethene
Formula -C₂H₄

Or
(i) Butane
Formula – C₄H₁₀

(ii) Propanal

Question 14.
Write two tests of alcohol.
Answer:

1. Ester test: When alcohol is heated with acetic acid, in the presence of sulphuric acid, sweet smelling ester is produced.
2. Sodium test: Alcohol reacts with sodium metal and always produces hydrogen gas.

Question 15.
(a) What do you understand by homologous series? Explain with an example.
Answer:
Homologous series. A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series. Each successive member differ by (- CH₂) group. All the members of a homologous series can be obtained by similar process.

General Formula : C_nH_2n+2
For example : Homologous series of alkane is as follows

(b) Write the first three homologous compounds of methane.
Answer:
Homologous Compounds of Methane

Question 16.
Define homologous series. What are its main properties?
Answer:
Homologous series. A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called homologous series. In this series the adjacent members differ by (-CH₂) group. Each member of a homologous series is called homolog.

Properties of Homologous Series :

• All the members of a homologous series can be represented by a common formula.
• Two successive members differ by one carbon atom and 2 hydrogen atoms.
• All the members of a homologous series possess similar chemical properties.
• There is a small difference between all the members of a homologous series.
• There is always a difference of 14 a.m.u. in atomic mass of two adjacent homologous.

Question 17.
What are alkanes? Write the properties of its main members. What do we conclude from its properties?
Answer:
Alkanes. The hydrocarbons with structural/general formula C_nH_2n+2 are called alkanes. The members of this group form an homologous series. Hydrocarbons like methane, ethane, propane and butane form many carbonic compounds which are collectively known as alkane. In these compounds, the number of carbon and hydrogen atoms differ by (- CH₂) for the next member of family.

Properties of Alkanes

Conclusions:

• Physical properties of alkane are based on their mass.
• First four members of alkane are in gasous state and alkanes having more than six carbon atoms are in liquid state.
• Alkanes having high molecular mass are found in solid state.
• Melting and boiling point of alkanes increase with increase in molecular mass.

Question 18.
What happens when hydrogen gas is passed through vegetable oils in the presence of nickel?
Answer:
Vegetables oils have double bond and polymerisation is possible. When nickel is used as catalyst, vegetable oil converts to vegetable ghee when hydrogen is passed through it because of hydrogenation. Vegetable ghee is solid like butter at room temperature.

Question 19.
Write the chemical properties of ethanoic acid.
Answer:
Ethanoic acid reacts with some metals, metal carbonates, hydroxides and bicarbonates.
1. Action with sodium:

2. Action with sodium hydroxide and potassium hydroxide:

3. Action with carbonate and hydrogen carbonate :
It reacts with carbonates and hydrogen carbonate to form water, salt and carbon dioxide.

Question 20.
Which type of oils should be used for cooking? Why?
Answer:
Animal fats have saturated fatty acids, which are harmful for health, whereas oils have long unsaturated carbon chains which are not harmful. Hence unsaturated fatty acids oils are used for cooking.

Question 21.
Write the ill-effects of using alcohol.
Answer:

• It is an addictive substance.
• It affects the sensitivity of nervous system.
• When a drunken person drives the vehicle he/she is not able to take the right decisions which leads to accident.

Question 22.
Why is consumption of methanol (CH₃OH) very fatal?
Answer:
Even a very small amount of methanol can prove fatal. In liver, it oxides to form methanale, which vigorously react with cells of liver, by which protoplasm gets emanating and swells in the same manner as boiled egg. Consumption of methanol also lead to blindness.

Question 23.
Write the IUPAC names of ethyl alcohol and acetic acid. Write the name of products formed when ethyl alcohol and acetic acid react in the presence of concentrated sulphuric acid. Write its chemical reaction.
Answer:

Compounds	IUPAC Names
1. Ethyl alcohol	ethanol
2. Acetic acid	ethanoic acid

Chemical reaction :

Question 24.
How will you prepare :
(a) ethyl alcohol from ethene
(b) acetic acid from ethyl alcohol?
Give reactions.
Answer:
(a) Ethene is heated with water in the presence of phosphoric acid to prepare ethyl alcohol

(b) Acetic acid is prepared by oxidation of ethyl alcohol

Question 25.
Write in brief the various industrial alcohols.
Answer:

• Absolute alcohol: It is 100% pure ethanol. It is produced by fractional distillation of ethanol which is prepared by fermentation of carbohydrates.
• Denatured alcohol: It is 95% ethanol and is used in industries. It is made poisonous by adding methanol, copper sulphate and pyridine, so as to make it unfit for drinking.
• Power alcohol: It is mixture of Benzene and Ether in 20% Ethanol and 50% gasolene. It is used to save petroleum.
• Alcoholic beverages: Alcohol is used as addictive drink. It is sold under various names like, rum, whisky, brandy, Jinn, etc.

Question 26.
Why is cleansing effect of soap not effective in hard water?
Answer:
Soaps are not effective in hard water for washing purposes because hard water has salts of calaium and magnesium. When soaps are dissolved in hard water, calcium and magnesium ions l’eact with water to form calcium and magnesium salts of fatty acids.

That is why a large amount of soap gets wasted. Calcium and magnesium salts being insoluble in water make precipitates and they get attached with the clothes and cause hinderance to the cleaning action and the clothes are not cleaned properly.

Question 27.
Distinguish between soaps and detergents.
Answer:

Soaps	Synthetic detergents
1. Soaps are sodium or potassium salts of higher fatty acids e.g. Sodium Stearate.	1. Synthetic detergents are Sodium alkyl Sulphates or Sodium alkyl benzene sulphates.
2. Soaps are prepared from vegetable oils or animal fats.	2. Synthetic detergents are prepared from the hydrocarbons obtained from petroleum.
3. Soaps have relatively weak cleansing action.	3. They have strong cleansing action.
4. Soaps form curdy white precipitates with calcium and magnesium salts present in hard water and hence, are not used in hard water.	4. Calcium and magnesium salts of detergents are soluble in water. Therefore no curdy white precipitates are obtained in hard water and hence synthetic detergents can be used even in hard water.
5. Soaps cannot be used in acidic medium as they are decomposed into carboxylic acids in acidic medium.	5. They can be used in acidic medium as they are the salts of strong acid and are not decomposed in acidic medium.
6. Soaps do not cause water pollution.	6. Synthetic detergents cause water pollution.
7. Soaps are biodegradable.	7. Some of the synthetic detergents are non biodegradable.

Question 28.
Write the formation of ethanol by fermentation process.
Answer:
Fermentation occurs in the presence of Bio-chemical catalysts at normal temperature by which sugar molecules convert into alcohol and carbon dioxide. These catalysts are known as enzymes, which means ‘yeast’ or ‘in the fermentation’.

Alcohol is formed by fermentation of sugar or starch. In a beaker, grape juice or glucose mixture is heated at 20° – 30°C in the presence of yeast. Sugar or starch molecules break into smaller molecules which produce carbon dioxide due to process of fermentation. This carbon dioxide is expelled out but air is not given inlet. A dilute mixture of ethanol is formed in water during fermentation. Ethanol is purified by distillation.

Chemical reaction :

Question 29.
Write the name of the reaction in which ethanoic acid and ethanol react together to form one product. Write the common name of the product.
Answer:
When ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid, ester is produced and this process is known as esterification.
CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

Question 30.
Observe the figure given below :

(i) Write the reaction taking place
Answer:

(ii) What is this reaction called?
Answer:
Esterification

Question 31.
What is indicated in the figure given below and give use of it.
Answer:
The figure indicates formation of micelle. Micelles are used to remove oily dirt from clothes.
1 – Hydrophilic end
2 – Oil droplet.

Question 32.
Show the bonds of Hydrogen, Oxygen and Nitrogen atoms respectively.
Answer:
1. Hydrogen: Two atoms of hydrogen by sharing of their electrons make hydrogen molecule (H2).

2. Oxygen: A double bond is made between two atoms of oxygen. Each atom of oxygen shares two electrons with other atom to form .an octet.

3. Nitrogen: Each atom of nitrogen shares three electrons to form an octet.

Question 33.
(i) Write molecular formula of Propane.
Answer:
C3H8

(ii) Write IUPAC name of

Answer:
Bromoethane.

Question 34.
What is detergent? Write the formation of synthetic detergents. Write its advantage.
Answer:
Materials used for cleaning purposes are known as detergents. Since long, soaps have been used as detergents but now-a-days synthetic detergents are more popular. The detergent molecule has two ends, one which is made of sulphate (-SO₄) or sulphonate (SO₃Na) group and it is hydrophilic by nature whereas other which is made of hydrocarbon is hydrophobic.

Synthetic detergent produces ample amount of lather even in hard water. These do not form insoluble salts of calcium or magnesium.

Question 35.
Which substances are used to produce synthetic detergents?
Answer:
Following substances are needed for production of synthetic detergents :

• Long chained hydrocarbons obtained from petroleum and coal.
• Concentrated sulphuric acid.
• Sodium hydroxide.

Procedure: Hydrocarbons are treated with cone, sulphuric acid to get hydrocarbonic sulphuric acid. It is further reacted with NaOH which forms synthetic detergents. About 15 to 30% of the total weight of washing powder is detergent. Rest of the others are various chemicals which provide other qualities.

Question 36.
What are the components of washing powder?
Answer:

• Synthetic detergents (15 to 30%).
• Sodium sulphate and sodium nitrate.
• Sodium tri-poly phosphate or sodium carbonate.
• Sodium perborate.

Very Short Answer Type Questions

Question 1.
Which element is present necessarily in the following items?
Food, clothes, medicines and hooks.
Answer:
Carbon.

Question 2.
On which element do all living processes depend?
Answer:
Carbon.

Question 3.
What percentage of carbon is present in minerals found under the crust of earth?
Answer:
0.02 %.

Question 4.
What percentage of CO₂ is present in atmosphere?
Answer:
0.003%.

Question 5.
How many electrons are present in the outer shell of carbon?
Answer:
4.

Question 6.
Why does carbon need four electrons to gain or lose?
Answer:
To attain noble gas configuration.

Question 7.
How does carbon gain four electrons?
Answer:
By making C₄^– anion.

Question 8.
How does carbon lose four electrons?
Answer:
By making C₄⁺ cation.

Question 9.
Which type of bond is shared by a pair of two hydrogen atoms?
Answer:
Single bond.

Question 10.
How is single bond between two atoms expressed?
Answer:
By single straight line.

Question 11.
What is the atomic number of nitrogen?
Answer:
7.

Question 12.
How many electrons are given by each atom of Nitrogen to complete the octet?
Answer:
3.

Question 13.
Which gas is used as a fuel the most?
Answer:
Methane gas.

Question 14.
Methane is the main constituent gas of which two fuel gases?
Answer:
Biogas, C.N.G.

Question 15.
Write the full form of C.N.G.
Answer:
Compressed Natural Gas.

Question 16.
How is the structure of diamond?
Answer:
Strong three-dimensional structure.

Question 17.
How is the structure of graphite?
Answer:
Hexagonal.

Question 18.
Which of these two is a good conductor of electricity diamond or graphite?
Answer:
Graphite.

Question 19.
Which is the hardest substance?
Answer:
Diamond.

Question 20.
How does it feel by touching graphite?
Answer:
Soft and slippery.

Question 21.
Which element has the ability to form large number of compounds?
Answer:
Carbon.

Question 22.
Give names of two elements which are placed in the group of carbon and have same valency.
Answer:
Valency of carbon is 4. This group has silicon and germanium.

Question 23.
What is the simplest form of hydrocarbon?
Answer:
Methane (CH₄).

Question 24.
In which types of bonds can carbon atoms join?
Answer:
Single, double, triple bond and ring-shaped.

Question 25.
Write the names of five elements which can make bond with carbon to form new compounds.
Answer:
Oxygen, Hydrogen, Nitrogen, Sulphur, Chlorine.

Question 26.
Write the formula of Ethane.
Answer:
C₂H₆.

Question 27.
Write the structural formula of Ethane.
Answer:

Question 28.
Give the next higher homo-logues of:
(i) C₃H₆
Answer:
C₄H₈

(ii) C₆H₈.
Answer:
C₇H₁₀.

Question 29.
Give the structure of ethanol.
Answer:

Question 30.
Name the functional group in propanone.
Answer:

Question 31.
Give the structure of simplest ketone.
Answer:
Simplest keton is acetone. It has the structure :

Question 32.
Give the name and structure of four carbon atoms in aldehyde.
Answer:

Question 33.
Name the products obtained when ethanol undergoes complete combustion.
Answer:
Carbon dioxide (CO₂) and Water (H₂O).

Question 34.
Give the structural formula of ethanol.
Answer:

Question 35.
Give the name and structure of functional group present in acetic acid (CH3COOH).
Answer:
Carboxyl group

Question 36.
Which of the following compounds belong to same homo-Iogous series?
C₂H₆O₂, C₂H₆O₂, C₂H₆, CH₄O
Answer:
C₂H₆ O, (C₂H₅OH) And CH₄O or (CH₂OH).

Question 37.
Give the structural formula of an ester.
Answer:

Question 38.
Give the names and structural formulas of acid and alcohol from which ethyl acetate is obtained.
Answer:
Acetic acid

and ethyl alcohol, CH₃CH₂OH

Question 39.
Give the electron-dot stucture of methane.
Answer:

Question 40.
Define covalent bond.
Answer:
It is formed by mutual sharing of electron pair between two atoms.

Question 41.
Explain what covalent compounds do not conduct electric current?
Answer:
This is because there are neither free ions nor free electrons.

Question 42.
Name the bond formed between metal atom and non-metal atoms.
Answer:
Ionic or electro valent bond.

Question 43.
What are allotropes?
Answer:
When an element exists in two or more form having different physical pruperties but, some chemical properties, there forms are called allotropes.

Question 44.
Define catenation.
Answer:
It is the property due to which a large number of atoms of the same element get linked together through covalent bonds forming long straight chains, branched chains and rings of different sizes.

Question 45.
Give two oxidising agents.
Answer:

1. Acidified potassium permanganate.
2. Acidified potassium dichromate.

Question 46.
Give the electron dot structure of ethane.
Answer:
Dot structure of ethane :

Question 47.
Give the structural formula of propane.
Answer:

Question 48.
Give the electron dot structure of ethene.
Answer:
Dot structure of ethene.

Question 49.
Define functional group.
Answer:
It is an atom or group of atoms which when present in a molecule gives special properties to it. e.g. C₂H₅OH has the functional group, -OH (hydroxyl group).

Question 50.
If two organic compounds have some functional group, predict they have similar physical or chemical properties.
Answer:
Similar chemical properties.

Question 51.
Give the general formulae of alkanes, alkenes and alkynes.
Answer:
Alkanes: C_n H_2n+2
Alkaenes: C_nH_2n
Alkynes: C_nH_2n-2, where n = No. if carbon atoms).

Question 52.
Give the structural formula of isomers of C₄H₁₀ (butane).
Answer:
Butane has two structural isomers :

Question 53.
Give the first four members of homologous series of alcohols.
Answer:
CH₃OH, C₂H₅OH. C₃H₇OH, C₄H₅OH.

Question 54.
Define a Catalyst.
Answer:
It is a substance which can increase the rate of a reaction but remains unchanged in mass and composition at the end of reaction.

Question 55.
What happens when a piece of sodium metal is added to ethanol? Give chemical equation also.
Answer:

Question 56.
What happens when ethanol is heated with conc. H₂SO₄ at 443K?
Answer:
Ethanol undergoes acidic dehydration to give ethene

Question 57.
What is denatured spirit or alcohol?
Answer:
It is prepared by adding poisonous substance like methanol, acetone, pyridine or copper sulphate to ethanol. It is unfit for drinking purposes.

Question 58.
Give three uses of ethanoic acid.
Answer:

1. In the manufacture of vineger
2. In the manufacture white lead
3. As a reagent in laboratory.

Question 59.
What is the atomic number of hydrogen?
Answer:
One.

Question 60.
Give the electronic configuration of carbon atom.
Answer:
(2, 4).

Question 61.
Give name of four carbon compounds.
Answer:
Methane, Chloroform, Ethanol and ethanoic acid.

Question 62.
Give two allotropic forms of carbon.
Answer:
Diamond and graphite.

Question 63.
Give the name of simplest ketone.
Answer:
Propanone (CH₃ COCH₃).

Question 64.
Give the name of first member of homologous series of alkynes.
Answer:
Ethyne (C₂H₂).

Question 65.
Give the name and formula of acid present in vinegar.
Answer:
Ethanoic acid (CH₃ COOH).

Multiple Choice Questions:

Question 1.
Ethanoic acid has the formula:
(A) C₂H₅OH
(B) CH₃COCH₃
(C) CH₃COOH
(D) C₂H₅COOH.
Answer:
(C) CH₃COOH

Question 2.
Carboxylic acids contain functional group:
(A) -CHO
(B) -CH₂OH
(C) -COOH
(D) -OH.
Answer:
(C) -COOH

Question 3.
The general formula of the alkyne is:
(A) C_nH_2n-2
(B) C_nH_2n+2
(C) C_nH_2n
(D) C_nH_2n+2.
Answer:
(A) C_nH_2n-2

Question 4.
Propanone has the functional group :
(A) -OH
(B) -CHO
(C) C=O
(D) -COOH.
Answer:
(C) C=O

Question 5.
Vinegar contains acetic acid:
(A) 5-8%
(B) 15-20%
(C) 21-29%
(D) 30-40%.
Answer:
(A) 5-8%

Question 6.
The reaction of acetic acid with ethyl alcohol is called :
(A) Polymerisation
(B) Saponification
(C) Hydrogenation
(D) Esterification.
Answer:
(D) Esterification.

Fill in the Blanks :

Question 1.
The functional group present in ethyl alcohol is ___________
Answer:
The functional group present in ethyl alcohol is alcoholic group (-OH)

Question 2.
CH₃—CH₂—OH represents ___________
Answer:
Ethyl alcohol.

Question 3.
Two atoms of the same element combine to form a molecule. The bond between them is known as ___________ bond.
Answer:
Covalent.

Question 4.
In the formation of oxygen molecule, the oxygen atoms share ___________ electrons each.
Answer:
Two.

Question 5.
The number of single covalent bonds in the molecule of ammonia is ___________
Answer:
Three.

Punjab State Board PSEB 10th Class Science Book Solutions Chapter 4 Carbon and its Compounds Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Science Chapter 4 Carbon and its Compounds

PSEB 10th Class Science Guide Carbon and its Compounds Textbook Questions and Answers

Question 1.
Ethane, with the molecular formula C₂H₆ has :
(a) 6 covalent bonds
(b) 7 covalent bonds
(c) 8 covalent bonds
(d) 9 covalent bonds.
Answer:
(b) 7 covalent bonds

Question 2.
Butanone is a four-carbon compound with the functional group :
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol.
Answer:
(c) ketone

Question 3.
While cooking, if the bottom of the vessel is getting blackened on the outside, it means that :
(а) the food is not cooked completely
(b) the fuel is not burning completely
(c) the fuel is wet
(d) the fuel is burning completely.
Answer:
(b) the fuel is not burning completely

Question 4.
Explain the nature of the covalent bond using the bond formation in CH₃Cl.
Answer:
The formation of CH₃Cl can be represented as :

Carbon forms single covalent bonds with three H- atoms and one Cl – atom by sharing one electron pair with each C-H bonds are non-polar. But C – Cl bond is polar because C and H leave almost same electronegativity whereas Cl has more electronegativity than carbon.

Question 5.
Draw the electron dot structures for :
(a) ethanoic acid
Answer:

(b) H₂S
Answer:

(c) propanone
Answer:

(d) F₂.
Answer:

Question 6.
What is an homologous series? Explain with an example.
Answer:
A series of compounds having similar structural formulae, same functional group and hence similar chemical properties is called a homologous series. In the homologous series any two adjacent members differ by CH2 unit in their molecular formulae.

For example homologous series of aldehydes (or alkanals) can be represented as :

H – CHO	Methanal
CH3 – CHO	Ethanal
CH3 – CH2 – CHO	Propanal
CH3 – CH2 – CH2 – CHO	Butanal
CH3 – CH2 – CH2 – CH2 – CHO	Pentanal and so on.

Question 7.
How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
Answer:
Differences between ethanol and ethanoic acid

Ethanol	Ethanoic acid
1. It is a colourless liquid having a pleasant smell.	1. It is colourless liquid having vineger like smell.
2. It has no action with a litmus solution.	2. It turns blue litmus solution red.
3. It has no action with sodium hydrogen carbonate solution.	3. It decomposes sodium hydrogen carbonate solution giving brisk effervescence of carbon dioxide gas.

Question 8.
Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?
Answer:
Soap molecule has two ends, one is hydrophilic, and it dissolves in water, while the other end is hydrophobic, and it dissolves in hydrocarbons. When soap is at the surface of water , the hydrophobic ‘tail’ of soap will not be soluble in water and the soap will align along the surface of water with the ionic end in water and the hydrocarbon ‘tail’ pointing out of water.

Inside water, these molecules have a unique orientation which keeps the hydrocarbon portion out of the water. This is achieved due to the formation clusters of molecules in which the hydrophobic tails are in the interior of the cluster and the ionic ends are on the surface of the cluster. This formation is called a micelle.

Such micelles can be formed in other polar solvents like ethanol.

Question 9.
Why are carbon and its compounds used as fuels for most applications?
Answer:
Carbon and its compounds are used as fuels for most applications because they bum producing a large amount of heat and light.

Question 10.
Explain the formation of scum when hard water is treated with soap.
Answer:
When soap is added to hard water, the soluble calcium and magnesium salts present in it react with soap to give insoluble calcium salt of soap which produces scum.

Question 11.
What change will you observe if you test soap with litmus paper (red and blue)?
Answer:
Soap solution will turn red litmus paper blue because soap is alkaline in nature.

Question 12.
What is hydrogenation? What is its industrial application?
Answer:
The addition of hydrogen to unsaturated hydrocarbons in the presence of catalysts like palladium, platinum, nickel etc. to give saturated hydrocarbons is called hydrogenation.

This reaction is used for hydrogenation of liquid vegetable oils using a nickel catalyst to get artificial or vanaspati ghee.

Question 13.
Which of the following hydrocarbons undergo addition reaction : C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄.
Answer:
Out of C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄; C₃H₆ and C₂H₂ undergo addition reactions because they contain multiple bonds.

Question 14.
Give a test that can be used to differentiate chemically between butter and cooking oil.
Answer:
Distinction between Butter and Cooking oil:

Butter	Cooking Oil
1. It is solid at room temperature.	1. It is liquid at room temperature.
2. Mix equal volumes of HgCl2 solution in 50% alcohol and 5% iodine solution in alcohol. To this add lg of butter. Violet colour does not fade away.	2. Mix equal volumes of HgCl2 solution in 50% alcohol and 5% solution of iodine in alcohol. To this add 1 ml of cooking oil. Violet colour fades away.
3. Take 2 g of butter in a test tube. To this add 1ml of cone. HCl and a few drops of 2% furfural solution in alcohol. Shake and allow to stand for 5 – 10 minutes. No rose red coloration appears.	3. Take 2 g of cooking oil in a test tube. To this add 1 ml of cone. HCl and a few drops of 2% .furfural solution in alcohol. Shake it and allow to stand for 5 – 10 minutes. Rose red coloration is obtained.

Question 15.
Explain the mechanism of the cleansing action of soaps.
Answer:
Mechanism of cleansing action of Soap:
Soaps are sodium or potassium salts of higher fatty acids e.g. sodium palmitate, C₁₅H₃₁COO^–Na⁺, sodium stearate, C₁₇H₃₅COO^–Na⁺ etc. A molecule of soap consists of two parts :

1. a long chain hydrocarbon part (C₁₅H₃₁^–, C₁₇H₃₅ …. etc.) which is soluble in oil and
2. ionic part on polar group, – COO^–Na⁺ which is soluble in water. Thus a molecule of soap can be represented as :

The long hydrocarbon chain is insoluble in water but soluble in oil and greases whereas the ionic or polar part is soluble in water. Soap has a capacity to clean a dirty piece of cloth whereas ordinary water cannot. The dirty clothes contain greasy and oily substance (dirt). Soap molecules dissociate in water to give carboxylate ion (RCOO^–) and cation (Na⁺). When soap added to dirty clothes dipped in water, the hydrocarbon part of carboxylate group dissolving in greasy or oily dirt particles where the polar (COO^–) group remain attached to water. In this way each oil droplet acquires negative charge.

The cleansing action of Soap

These negative charged oil droplets called micelles cannot coalesce and hence form a stable emulsion water. These small droplets along with dirt can be easily washed away with water. Thus the soap helps in removing greasy dirt by producing a stable oil in wrater type emulsion. Also the soap reduces surface tension of water. Hence cloth is wetted more effectively and is cleaned.

Science Guide for Class 10 PSEB Carbon and its Compounds InText Questions and Answers

Question 1.
What would be the electron-dot structure of carbon dioxide which has the formula CO₂?
Answer:
In carbon dioxide, carbon atoms are bonded with two oxygen atoms. The atomic number of carbon is 6, and it has four electrons in the outer shell.

To make an octet it requires four electrons. Oxygen requires only two electrons in the outer shell. Therefore electron-dot structure will be :

Every oxygen atom is joined to carbon atom by double bond.

Question 2.
What would be the electron-dot structure of a molecule of sulphur which is made up of eight atoms of sulphur? (HINT. The eight atoms of sulphur are joined together in the form of ring.)
Answer:
The atomic number of sulphur is 16

Sulphur has 6 electrons in the outermost shell and to complete an octet it requires 2 electrons.
∴ Sulphur atom will share 2 electrons. It’s chemical formula is S₈.

Question 3.
How many structural isomers can you draw for pentane?
Answer:
Three ; n-Pentane, iso-pentane, neo-pentane.
Structural isomers can be drawn for pentane.

Question 4.
What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?
Answer:

1. Catenation: The carbon atoms have an astonishing property to combine and form bond with other carbon atoms to form long chain compounds. This property is known as catenation. In this, either long chain of carbon are in ring form or the carbon atoms join in single, double or triple bond.
2. Tetravalency: Carbon has four electrons in the outermost shell. That is why its valency is four and it has got capacity to make bonds with other elements. Oxygen, Hydrogen, Nitrogen, Sulphur, Chlorine and many other elements can make new compounds with the help of carbon.

Question 5.
What will be the formula and electron dot structure of cyclopentane?
Answer:
Molecular formula of cyclopentane = C₅ H_{2 × 5} = C₅H₁₀

Question 6.
Draw the structures for following compounds :
Are structural isomers possible for bromopentane?
(i) Ethanoic acid
Answer:
Ethanoic acid (CH₃COOH)

(ii) Bromopentane
Answer:

Due to exchange of position of carbon with bromine, many isomers of bromopentane are possible.
For example :

(iii) Butanone
Answer:

(iv) Hexanal.
Answer:

Question 7.
How would you name the following compounds?
(i) CH₃ – CH₂ – Br
Answer:
Bromoethane

Answer:
Methanal

Answer:
Hex-1-yne.

Question 8.
Why is the conversion of ethanol to ethanoic acid an oxidation reaction?
Answer:
This is because in this reaction oxygen gets added to ethanol.

Question 9.
A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?
Answer:
A mixture of ethyne and air is not burnt for welding. This is because air also contains nitrogen along with oxygen. Nitrogen will also burn in oxygen producing oxides of nitrogen such as nitre oxide (NO) and nitrogen dioxide (NO₂) which cause pollution.

Question 10.
How would you distinguish experimentally between an alcohol and a carboxylic acid?
Answer:
The following two tests are used :

• Litmus test: Treat the given compound with blue litmus solutions. If the blue litmus solution turns red, it is a carboxylic acid and if does not turn red, it is an alcohol.
• Sodium bicarbonate test: Add some sodium bicarbonate solution to the given compound. If their is a brisk evolution of a colourless and odourless gas (CO₂) which turns freshly prepared lime water milk, it is carboxylic acid and if their is no effervescence, it is an alcohol.

Question 11.
What are oxidising agents?
Answer:

• The substances which can oxidise other substances by giving oxygen are called oxidising agents.
• Examples: Alkaline potassium permanganate solution, acidified potassium dichromate solution, etc.

Question 12.
Would you be able to check if water is hard using a detergent?
Answer:
No, we can’t check whether the water is hand or soft using a detergent.

Question 13.
People use a variety of methods to wash clothes. Usually after adding the soap, they ‘beat’ the clothes on a stone, or beat it with a paddle, scrub with a brush, or the mixture is agitated necessary to get clean clothes?
Answer:
This is because when soap molecules dissolve in the dirt, the dirt is somewhat loosened from the clothes, and in order to remove it from clothes, the clothes have to be beaten on a stone or beaten with a paddle or scrubbed with a brush or mixture has to be agitated in washing machines.

Punjab State Board PSEB 10th Class Science Book Solutions Chapter 6 Life Processes Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Science Chapter 6 Life Processes

PSEB 10th Class Science Guide Life Processes Textbook Questions and Answers

Question 1.
The kidneys in human beings are a part of the system for :
(a) nutrition
(b) respiration
(c) excretion
(d) transportation.
Answer:
(c) excretion.

Question 2.
The xylem in plants are responsible for :
(a) transport of water
(b) transport of food
(c) transport of amino acids
(d) transport of oxygen.
Answer:
(a) transport of water.

Question 3.
The autotrophic mode of nutrition requires :
(a) CO₂ and water
(b) Chlorophyll
(c) Sunlight
(d) All of the above.
Answer:
(d) All of above.

Question 4.
The breakdown of pyruvate to give CO₂, water and energy takes place in :
(a) cytoplasm
(b) mitochondria
(c) chloroplast
(d) nucleus
Answer:
(b) mitochondria.

Question 5.
How are fats digested in our bodies? Where does the process take place?
Answer:
Digestion of fats takes place in the intestine. The fats are emulsified by the bile salts present in bile. The emulsified fats are acted upon by pancreatic lipase (strepsin) which hydrolyses fats into fatty acids and glycerol. The intestinal lipase also hydrolyses the emulsified fats into fatty acids and glycerol.

Question 6.
What is the role of saliva in the digestion of food?
Answer:
Role of saliva

• Saliva lubricates the food and facilitates mastication.
• Saliva binds the food molecules together.
• Saliva contains ptyalin (salivary amylase) enzyme which acts on starch, glycogen and other carbohydrates to form maltose.

Question 7.
What are the necessary conditions for autotrophic nutrition and what are its byproducts?
Answer:
Photosynthesis is essential in case of autotrophic nutrition

Conditions required for photosynthesis

• CO₂ is necessary for photosynthesis.
• Water is required.
• Sunlight is necessary for photosynthesis.
• Chlorophyll is essential for photosynthesis.
• By-products. Molecular oxygen is liberated as a byproduct.

Question 8.
What are the differences between aerobic respiration and anaerobic respiration? Name some organisms that use anaerobic mode of respiration.
Answer:
(a) Differences between aerobic and anaerobic respiration

Aerobic respiration	Anaerobic respiration
1. It takes place in the presence of oxygen.	1. It takes place in the absence of oxygen.
2. It is completed in cytoplasm and mitochondria of cells.	2. It is completed in the cytoplasm only.
3. It involves the complete oxidation of glucose into CO2 and H2O and a large amount of energy is released.	3. It involves the incomplete oxidation of glucose into CO2 and alcohol or lactic acid and less amount of energy is released.
4. The process is harmless.	4. It is toxic to plants.

(b) Anaerobic respiration takes place in bacteria and yeast.

Question 9.
How are alveoli designed to maximise the exchange of gases?
Answer:

Question 10.
What would be the consequences of a deficiency of haemoglobin in our bodies?
Answer:
Haemoglobin is a respiratory pigment present in RBC of blood. It has high affinity for oxygen. One molecule of haemoglobin carries 4 molecules of oxygen. If simple diffusion were to move oxygen in our body, it is estimated that it would take 3 years for a molecule of oxygen to reach tip of toes from lungs.

Question 11.
Describe double circulation in human beings. Why is it necessary?
Answer:
Double circulation. In human beings heart is four-chambered, having right and left auricles and right and left ventricles. The right auricle receives the deoxygenated blood from the body and sends it into the right ventricle that pumps it to the lungs via a pulmonary arch for oxygenation. The left auricle receives oxygenated blood from the lungs and sends it into the left ventricle, which pumps it to the body through a single aortic arch.

Significance:

• Thus, the deoxygenated and oxygenated blood remain fully separate, and there is complete double circulation.
• It increases efficiency.

Double circulation of blood in birds and mammals.

Question 12.
What are the differences between the transport of materials in xylem and phloem?
Answer:
Differences between transport in xylem and phloem

Transport in xylem	Transport in phloem
1. Water and minerals are transported through xylem.	1. Sucrose, amino acids and other substances are transported through phloem.
2. Xylem helps in upward movement, i.e. from roots to stem, branches and leaves.	2. Phloem is responsible for downward and lateral movement from leaves to other parts.

Question 13.
Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
Answer:

• Alveoli of lungs remove CO₂ as a waste during exchange of gases and nephrons filter wastes from blood.
• Alveoli are supplied with extensive network of blood capillaries for gaseous exchange. Bowman’s capsule surrounds a cluster of capillaries for filtration.
• Both increases surface area either for gaseous exchange or filtration.
• Urea and uric acid wastes are removed in the nephron.
• Both purify blood lungs alveoli by removing waste gases and nephrons by filtering the waste products in the form of urine.

Science Guide for Class 10 PSEB Life Processes InText Questions and Answers

Question 1.
Why is diffusion insufficient to meet the energy requirements of multicellular organisms like humans?
Answer:
In multicellular organisms, all the cells of body may not be in direct contact with the surrounding source of oxygen i.e. environment, thus simple diffusion will not meet the oxygen requirements of all the cells. These organisms require specialised organs to meet the oxygen requirement.

Question 2.
What criteria do we use to decide whether something is alive?
Answer:
Features of living organisms

• Movements
• Growth
• Metabolism
• Cellular body
• Nutrition
• Respiration
• Transportation
• Excretion
• Respond to stimuli
• Reproduction.

Question 3.
What are outside raw materials used by living organism?
Answer:
Outside raw materials used by living organism

• Energy obtained from food.
• Oxygen: Required for breaking down of carbon based molecules to liberate energy in the body.
• Water: It is required for proper digestion of food and other functions in the body. It is raw material for photosynthesis in plants. All reactions occur in solution form in the body.
• CO₂ Raw material for photosynthesis in plants. All reactions occur in solution form in the body.

Question 4.
What processes would you consider essential for maintaining life?
Answer:

• Nutrition
• Respiration
• Transportation
• Excretion.

Question 5.
What are the differences between autotrophic and heterotrophic nutrition?
Answer:
Differences between Autotrophic and Heterotrophic nutrition

Autotrophic Nutrition	Heterotrophic Nutrition
1. It occurs in green plants and blue green algae.	1. It occurs in animals and insectivorous plants.
2. CO2 and water are raw materials which combine to form organic compound.	2. They depend on plants and herbivore for their food.
3. They need chlorophyll and sunlight	3. There is no need of chlorophyll and sunlight,

Question 6.
Where do the plants get each of raw materials required for photosynthesis? (PB. Board 2011)
Answer:
Raw materials of photosynthesis

• CO₂
• Water.
• Nitrogen

1. CO₂ is obtained from air. It enters the leaf through stomatal openings.
2. Water is obtained from soil. It enters the leaf through the mid-rib and vein from the root which absorbs it from the soil.
3. Nitrogen: It is obtained from soil.

Question 7.
What is the role of acid in our stomach?
Answer:
HCl is obtained from gastric glands present in the wall of the stomach.

Functions of HCl:

• It provides acidic medium. It is required for the action of enzymes. It changes the pH of food from almost neutral to acidic medium (from pH 7 to 2)
• Activates the inactive proenzyme propepsin into active pepsin.
• Kills the bacteria present in food.
• It softens calcium.
• It regulates the opening and closing of the pyloric aperture.

Question 8.
What is the function of digestive enzymes?
Answer:
Role of digestive enzymes: These enzymes convert the complex non-diffusible form of food into simple diffusible form.

• Ptyalin converts starch into maltose.
• Pepsin breaks down proteins into peptides and amino acids.
• Rennin curdles milk protiens so that they can stay for longer period to be acted upon by pepsin.
• Lipase acts on fats and forms fatty acid and glycerol.
• Maltase acts on maltose and forms glucose.

Question 9.
How is small intestine designed to absorb digested food?
Answer:
Small intestine is a long tubular structure. The inner wall of small intestine is thrown into folds called villi. The absorptive cells have numerous finger-like processes called microvilli. They increase the surface area for absorption of food. These villi have blood vessels named lacteals from absorption of food.

Question 10.
What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Answer:
The amount of oxygen dissolved in water is very low as compared to the amount of oxygen in air. Thus these organisms have to make less efforts to obtain oxygen.

Question 11.
What are the different ways in which glucose is oxidised to provide energy in various organisms?
Answer:
Different pathways to provide energy from glucose

Question 12.
How is oxygen and CO₂ transported in human beings?
Answer:
1. Transport of oxygen: It is transported from respiratory organs to body cells,
1. Haemoglobin helps in the transport of oxygen. In the alveoli of the lungs, the haemoglobin (Hb) present in red blood corpuscles combines with oxygen to form oxyhaemoglobin. When the blood reaches the tissue, oxygen is released from the oxyhaemoglobin for the consumption by the tissues.
Hb + O₂ → HbO₂

2. Some of O₂ is transported in the solution form by plasma of blood.

2. Transport of CO₂

• CO₂ diffuses into blood plasma to form physical solution.
• CO₂ forms unstable carbonic acid with water and is transported as such.
• CO₂ is also transported from tissue to lungs as bicarbonates.

Question 13.
How are lungs designed in human beings to maximise the area for exchange of gases?
Answer:
Within the lungs, the primary bronchi divides into smaller and smaller tubes which finally terminate into balloon-like structures called alveoli. These alveoli increase the surface area for exchange of gases. There are 750 million alveoli in the lungs of man. If the alveolar surface is spread out it would cover about 80 m2. Thus it makes efficient exchange of gases.

Each alveolus or air sac has a diameter of 75 to 300 microns and has a very thin wall. The walls of the alveoli are elastic and are supplied with capillaries. Through these thin walls gases are exchanged between the capillaries and the air sacs.

Question 14.
What are the components of the transport system in human beings? What are the functions of these components?
Answer:
There are two main transport systems in human beings :

1. Blood vascular system.
2. Lymphatic system.

Components of blood vascular system

• Blood: It is a reddish viscous fluid connective tissue. In an adult human being, it is 5-6 litres in amount. Blood consists of two parts – plasma and formed elements. (RBCs, WBCs and blood platelets). Blood transports digested food, oxygen, carbon dioxide, nitrogenous wastes and hormones in the body.
• Heart: It is a hollow, muscular pumping organ. The heart sends the blood to lungs. Heart pumps the blood in the body.
• Blood vessels: The blood vessels which carry oxygenated blood are called arteries. They divide to form capillaries of finer dimensions. Exchange of materials takes place across the capillaries. It is possible because the walls of capillaries are extremely thin. The blood from the tissues is returned by veins.

Components of Lymphatic system

1. Lymph: It acts as middle man between blood and tissue. It destroys harmful bacteria
2. Lymph vessels
3. Lymph capillaries
4. Lymph nodes

Question 15.
Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Answer:

• In the heart of these organisms the left side has oxygenated blood and right side deoxygenated blood.
• The separation of blood allows a highly efficient supply of oxygen to the body.
• It is essential for such animals which have high energy needs.
• They also constantly use energy for maintaining body heat.

Question 16.
What are the components of transport system in highly organised plants?
Answer:
Components of transport system in plants

• Xylem tissue. Vessels and tracheids of roots, stems and leaves are concerned with transport of water and minerals in plants.
• Phloem consists of sieve tubes and companion cells. It transports food, amino acid, phytohormones and other substances from leaves to various parts of plants.

Question 17.
How are water and minerals transported in plants?
Answer:
Transport of water and minerals
1. In xylem tissue, vessels and tracheids of the roots, stems and leaves are interconnected to form a continuous system of water conducting channels reaching all parts of the plants.

2. Plants absorb water and minerals through their entire surface i.e., roots, stem and leaves. However, mainly the water is absorbed by roots from soil.

3. The area of young roots where most of the absorption takes place is the root hair zone.

4. This zone is the area of greatest permeability.

5. Passage of water in root or pathway of water in root

• The entry of water into the root hair dilutes the cell sap. Thus water molecules in root hair increase as compared to adjacent cortical cells.
• Water reaches the passage cells of endodermis. These passage cells lie opposite the xylem.
• They allow water to entre the pericycle.
• So, water enters the xylem from pericycle for upward movement of sap.

6. The Ascent of Sap:
The upward movement of water from the root towards the top of the plant in the xylem vessels is called ascent of sap. The upward transport of water and minerals in plants which are in some cases as tall as 400 ft. poses a serious problem.

7. Transpiration also helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves.

Question 18.
How is food transported in plants?
Answer:
Transport of food in plants:
The food prepared in the green leaves of plants is transported through phloem in the form of sucrose solution to storage organs of roots, seeds and fruits. This process is called translocation. This process requires energy. It is provided by ATP molecules. This increases the osmotic pressure in the tissue causing water to move into it. This pressure moves the material in the phloem to tissues which have less pressure.

Question 19.
Describe the structure and functioning of nephron.
Or
How does urine formation occur in human?
Answer:
Structure of a Nephron:
A nephron is made up of:

• a globular double-walled Bowman’s capsule around a clump of capillaries or glomerulus, and
• a tubule surrounded by blood capillaries.

The tubule consists of
(a) a proximal convoluted portion
(b) the loop of Henle, with descending and ascending limbs, and
(c) a distal convoluted part.

The nephron empties into a collecting duct. The two million nephrons of a human being, end to end would extend for nearly 80 km. All the collecting ducts discharge into a central cavity of the kidney (pelvis) that connects to the ureter.

Functioning of Nephron
Urine is formed by 3 processes: glomerular filtration, tubular reabsorption and tubular secretion in the nephrons of the kidney.
1. Ultrafiltration (Glomerular filtration):
Blood is filtered under pressure in the glomeruli present in the cup-like structure of Bowman’s capsule. Glomerular (nephric) filtrate is formed.

Nephron and its function

2. Tubular reabsorption:
In the PCT, entire glucose, amino acids, vitamins and hormones, most of the inorganic ions are reabsorbed by active transport, most of water by osmosis, and some urea by back diffusion from nephric filtrate.
Loop of Henle mainly concentrates urine to conserve water. Here, some inorganic ions are actively taken up and some water leaves by osmosis.

3. Tubular secretion:
In the DCT, collecting tubule and collecting duct, many ions, water (depending upon availability) are secreted in to DCT and collecting duct.
Urine formed passes into bladder from kidney through ureters.

Question 20.
What are the methods used by plants to get rid of excretory products?
Answer:
Excretory products of plants include CO₂, salts, resins, tanins latex etc. Excretion in Plants

• Excess of water passes out during transpiration.
• Plants get rid of dead tissue as a measure to eliminate waste.
• Waste products may be stored in cellular vacuoles.
• Waste products may be stored in leaves which fall off.
• Resins and gums are stored in old xylem.
• Plants also excrete wastes into soil.
• Aquatic plants lose their waste products by diffusion into the water.

Question 21.
How is the amount of urine produced regulated?
Answer:

• Amount of urine formed depends upon the availability of water in the body.
• ADH (Antidiuretic Hormone) regulate the amount of water.
• Osmoregulation helps in regulation of salts and water.
• Urine is stored in urinary bladder.

Punjab State Board PSEB 10th Class Science Important Questions Chapter 3 Metals and Non-metals Important Questions and Answers.

PSEB 10th Class Science Important Questions Chapter 3 Metals and Non-metals

Long Answer Typt Questions

Question 1.
Show various steps involved in extraction of metal from an ore by a sketch.
Answer:

Steps involved in the extraction of metals from ores.

Question 2.
Give methods of enrichment of ores.
Answer:
Methods of enrichment of ores. Ores or minerals are mined from earth these are usually contaminated with large amount of impurities which are called gangue. It is necessary to remove these impurities before extraction of metals. By removing gangue the ore is enriched and concentration of metal is increased. Therefore ore in enriched prior to other processes. Methods of removing gangue from ore depends on the difference of physical and chemical properties of both of them.

Enrichment of ore using magnetic method.

Physical methods of enrichment :

• Hydraulic Washing: In this method finely powdered ore is washed with jet of water. In this strong flow of water light gangue particles are washed away where as heavy ore particles settle down, Tin and lead ores are enriched by this method.
• Froth Floatation Method: In this method, mixture of powdered ore and water or some appropriate oil is taken in a tank. Ore particles are coated with oil and gangue particles are wet with water. A blast of compressed air is blown through the pipe of a rotating agitation to produce froth, due to this, mineral particles wetted with oil change into foam and float on the surface of water. Froth containing ore particles is easily transferred to another container sulphides of copper, lead and zinc are enriched by this method.

Chemical Methods: The chemical method used for the concentration of the ore is based on the difference in some chemical property of the metal and the impurities. An example of this method is the concentration of bauxite ore of aluminium.

Concentration of aluminium ore by Bayer’s process: In this method, Bauxite is reduced by treating it with hot sodium hydroxide. It gives sodium meta aluminate (NaAlO₂) which is soluble in water. The solution in filtered to remove the gangue present in the ore because it does not dissolve in sodium hydroxide. NaAlO₂ is allowed to react with hydrochloric acid to obtain Aluminium hydroxide. On strong heating aluminium hydroxide pure aluminium oxide is obtained.

Following reactions take place

Question 3.
Explain General methods used in the extraction of metals.
Answer:
Steps involved in the extraction of metals :

• Enrichment (concentration) of ore.
• Converting concentrated ore into oxide.
• Reduction of metal oxide to obtain metal.
• Refining of impure metal.

1. Concentration :
(A) Hydraulic washing: This method is used for concentration of oxide ores Gangue particles are lighter as compared to ore particles. In this method powdered ore is washed with flowing water. Light gangue particles are washed away with water and heavy ore particles are left.

(B) Froth floatation method: In this method powdered ore is taken in a tank containing water pine oil is also added to it. Sulphide ore is wet with oil and gangue is wet with water.

The water is agitated by blowing compressed air violently, a froth is formed on the surface of water. This froth carries the lighter ore particles along with it to the surface. Gangue particles are heavy and settle to the bottom.

(C) Magnetic separation.

Enrichment of ore using magnetic method.

1. Magnetic method: This method is acceptable for magnetic impurities like iron, cobalt, Nickel etc. Minerals which are of magnetic nature got attracted towards magnetic field. Chromite and pyrolusite ores are enriched by this method. In this method ground ore is placed on a conveyer belt. This belt goes around two rollers one of which is magnetic. When ore comes near the magnetic roller then two heaps of magnetic and non magnetic materials are obtained. Iron ore magnetite is enriched by this method.

(D) Chemical separation: This process is based on the difference between chemical – properties of ores and gangue eg. Bauxite Al₂O₃.2H₂O is impure form of aluminium oxide. It contains Iron (III) oxide (Fe₂O₃) and sand (SiO₂) as main impurities. Due to iron (III) oxide its colour is red brown. Bayer’s process is used to obtain pure aluminium from / bauxite. In this methods powdered ore is mixed with heated sodium hydroxide.
Al₂O₃ (S) + 2NaOH (aq) → 2NaAlO₂ (aq) + H₂O (l)
NaAlO₂ (aq) + 2H₂O (l) → Al(OH)₂ (s) + NaOH (aq)

2. Converting concentrated ore into metal oxide
Roasting: In this process ore is heated in the presence of air to obtain metal oxide. Which can easily be reduced to obtain the metal.

Zinc blende contains zinc sulphide when concentrated zinc blende ore (zinc sulphide) is roasted in air then it gets oxidized to give zinc oxide.

Calcination: In this process ore is heated in the absence of air to remove moisture and volatile impurities.
When carbonate ore is heated it dissociates to give metal oxide.

3. Extracting metals from metal oxide.
To obtain metal from metal oxide it is heated with some reducing agent. To obtain metals zinc, iron, tin etc. their oxides ore heated with carbon which acts as reducing agent.
ZnO(s) + C(s) → Zn(s) + CO(g)

Oxides of metals with medium activity can be reduced by using highly reactive metals like sodium, calcium and aluminium etc.
3MnO₂(s) + 4Al(s) → 3Mn(l) + 2Al₂O₃(s) + heat

4. Electrolytic refining.
In this method impure metal is taken as anode and a thin strip of pure metal is taken in the form of cathode metal salt solution is taken as electrolyte. When electric current is passed through the electrolyte, pure metal from anode dissolves into solution and impurities settle down as anode mud.

Electrolytic refining

Question 4.
(a). How do metals and non-metals react?
Answer:
Metals and non-metals react on the basis of electronic configuration in the valence shell.

Sodium has only one electron in its outer most shell. If it lose its electrons of the M shell then L will become its outermost shell which have complete octet. Nucleus of this atom will have 11 protons but number of electrons is 10, therefore it is positively charged and gives Na+ sodium positive ions. On the other side, there are 7 electrons in the outer most shell of chlorine and it requires one electron to complete its octet. If there is reaction between chlorine and sodium then lost electron of sodium atom is gained by chlorine atom and chlorine atom becomes negatively charged by one unit. Because there are 17 protons in the nucleus of the chlorine atom and there are 18 electrons in K, L and M shells. Therefore, chloride negative ions Cl- is obtained.

Due to opposite charges sodium and chloride ions attract each other and they form strong bonds involving electrostatic forces and form sodium chloride.

Another ionic compound, magnesium chloride is shown in fig.
Formation of NaCl and MgCl₂ by Electron transfer :

Formation of sodium chloride.

Formation of sodium chloride.

Compounds formed by metals and Non-Metals by the transfer of electrons between them are called ionic or electrovalent compounds.

(b) Write four main exceptions from normal properties of metals and Non-Metals.
Answer:

• All the metals are solid at room temperature except mercury. Melting point of metal is usually high but of Gallium and Cesium is low.
• Iodine is a non-metal but still shiny.
• Carbon is a non-metal which can have many forms. Diamond is allotrope of carbon. It is the hardest substance found in nature. Its melting and boiling point are very high. Another allotrope of carbon is graphite which is conductor of electricity.
• Alkali metal (lithium, sodium, Potassium) are so soft that these can be cut by knife. They have low density and low melting point.

Question 5.
How will you differentiate between metals and non-metals?
Answer:
Differences between metals and non-metals on the basis of physical properties :

Metals	Non-metals
1.         All metals are solid at room temperature. But mercury is liquid at room temperature.	1. Non-metals exist in all the three states at room temperature. Phosphorous and sulphur are solid, H2, O2, N2 in gaseous state, and bromine in liquid state.
2. Metals are ductile, malleable and tenacious.	2. These are soft.
3. Metals have lustre i.e. metal shine.	3. They do not have lustre but diamond, graphite and iodine are exceptions.
4. Metals are good conductors of heat and electricity but bismuth is exception.	4.All non metals are non conductors except graphite and carbon gas.
5. Metals have high melting and boiling points.	5. Non metals have low melting and boiling points.
6. Metals are hard but sodium and potassium can be cut by knife.	6. These are not very hard but diamond is the hardest substance.
7. Metals have very high relative densities but Na, K are exceptions.	7. Non metals have very low relative densities.
8. Metals are opaque.	8. Gaseous non metals are transparent.

Difference between metals and non-metals on the basis of chemical properties

Metals	Non-metals
1. Metals form alkaline oxides some of them form bases.	1. Non-metals form acidic or neutral oxides.
2. Metals react with acids to displace hydrogen and form salts.	2. Non-metals do not displaces hydrogen from acids.
3. Metals are electropositive in nature.	3. Non-metals are electronegative in nature.
4. Metals combine with chlorine to form chlorides which are electrovalent compounds.	4. Non-metals combine with chlorine to form chlorides which are covalent compounds.
5. Some metals combine with hydrogen to form hydrides which are electrovalent.	5. Non-metals combine with hydrogen to form hydrides which are covalent.
6. Metals are reducing agents.	6. Non-metals are oxidizing agents.
7. Metals form positive ions in aqueous solution.	7. Non-metals form negative ions in aqueous solution.

Question 6.
Discuss about the extraction of metals
Answer:
Some metals are found in free state in nature. Some metals are found in the form of compounds. Metals at the bottom of reactivity series show very low reactivity. These are found in free state. Gold, silver, platinum and copper are found in free state.

Copper and silver are also found in the form of sulphide and oxide ores. Metals (K, Na, Ca, Mg and Al) which are at the top of reactivity series show very high reactivity that they are never found in free state. Metals at the middle of the reactivity series (Zn, Fe, Pb etc.) are moderately reactive. These are found in the form of oxide, sulphide or carbonate. Some metal ores are found in the form of oxides.

Metals are classified into three types:
(a) least reactive metals
(b) Moderately reactive metals
(c) highly reactive metals.

Reactivity series and metallurgy

Question 7.
What is rust? What are the requirements necessary for its completion? Give ways to prevent rusting of iron?
Answer:
Surface of iron aquires a coating of a brown flaky substance called rust. It is a compound of Iron (III) Oxide and iron (III) hydroxide. It weakens the iron surface. Due to this, a great loss occurs to the iron articles.

The presence of moisture and air is necessary for rusting of iron. This can be proved with an experiment. If we take new shining irons nails in three test tubes as shown, then we find that nails which are in contact with water and air, got rusted. If we completely immerse the nails in water and cover the water surface with oil so that there is no air available for the nails, then nails will not get rusted.

Similarly if we use CaCl, in the test tube absorbs all the moisture so that no moisture is available in this case also, nails will not get rusted.

Ways to Prevent Rusting :

1. Using oil or grease on the surface: If iron surface is covered with oil or grease it does not remain in contact with air and thus rusting is prevented. Machine parts are saved by this method.
2. Using enamel: By painting iron surface, rusting can be prevented. Buses, cars, scooter, motor cycle, windows, trains etc. are saved by this method.
3. Covering with plastic: Iron surface is covered with plastic. Iron furniture is saved by this method.
4. Galvanization: A process of coating thin layer of zinc on iron is called galvanization. This method is used to prevent buckets, tubs, drums, iron sheets etc. from rusting.
5. By electroplating: Iron can be electroplated by metals like Nickle, Chromium, aluminium etc. Rims, handles, bumpers etc. of vehicles are prevented from rusting by this method.
6. By tin: Iron is coated with tin. Ghee canisters, boxes used for packing food are tinned.
7. Converting to steel: Iron can be preverted from rusting by converting it into steel.

Question 8.
Explain General properties of ionic compounds.
Answer:
General properties of ionic compounds are given below:

• Physical nature: Due to strong force of attraction between positive ions and negative ions, ionic compounds are solid. They are brittle and break on pressing.
• Melting and boiling point: They have high melting and boiling points. Because a large amount of energy is required to break the strong inter ionic attraction.
• Solubility: Ionic compounds are normally soluble in water but are insoluble in Kerosene, Petrol etc.
• Electric Conductivity: In solid form ionic compounds do not conduct electricity because of strong and firm structure. Movement of ions is not possible. But ionic compounds can conduct electricity in molten state, because electrostatic force of attraction becomes very weak due to heat energy. Therefore ions can move freely and electric current can pass through it. Mobility of charged particles is necessary for conduction of electricity in a solution. Ions are present in aqueous solution of ionic compounds. When electric current is passed through the solution then ions start moving towards the opposite electrodes.

Question 9.
What is an alloy? Magnetic iron oxide explain the objective of their formation?
Answer:
Alloy: An alloy is a homogeneous mixture of a metal with another metal or non-metal, e.g. solder is an alloy of lead and tin (Pb and Sn). Stainless steel, solder, brass, bronze, bell metal etc.

Uses of alloys :

• For increasing hardness: Iron is mixed with carbon to form stainless steel which is harder than iron. Copper is mixed with gold and lead is mixed with silver to make them hard. Duralium is an alloy made from aluminium and is very hard.
• Increasing strength: Steel, Duralium are hard as well as strong.
• Preventing Corrosion: By making stainless steel an alloy of iron, which do not get rusted.
• To produce sound: Bell metal is an alloy of copper and tin used to produce loud sound.
• To lower melting point: An alloy of Bismuth, tin and lead has low melting point.
• Moulding: Bronze and type metal.
• For change in colour: Aluminium bronze is an alloy of copper and aluminium is of golden colour.
• Domestic uses: Alloys are used in homes, factories, offices etc. e.g. utensils, almirahs, fans, refrigerators elements etc. are made up of alloys.

Question 10.
Explain the activity series of metals.
Answer:
All metals have different rates of activity. Some metals like sodium, potassium and calcium etc. are highly reactive. These metals combine with oxygen to form oxide and react with hydrogen to form hydrides. Some metals are compratively less reactive e.g. iron, zinc etc. Some metals are least reactive e.g. gold, silver. Reactivity of metals depends on their ability to lose electrons, Metals are arranged in a list in decreasing rate of their activity.

Metals which are above hydrogen are more reactive and those below hydrogen are lower in reactivity and are found in free state. In this series potassium is the most reactive metal in this series.

Short Answer Type Questions

Question 1.
Name two metals which are good conductors of heat and electricity. Name metals which are highly and least conducting with reference to heat.
Answer:
Copper and aluminium are good conductors of electricity and heat. Silver is very good conductor of heat whereas lead is not a good conductor of heat.

Question 2.
Define ductility with example.
Answer:
Property of drawing thin wires from a metal is called ductility. Gold is the highest ductile metal. We can draw 2 km long wire from 18 carat gold.

Question 3.
What is electrical conductivity? Name the metals which have the highest conductivity, less than this and the lowest conductivity.
Answer:
It is the ease with which electric current can flow through a metal. Those metals which offer very low resistance to the flow of current they have high conductivity. Silver, copper are very good conductors of current then comes gold, aluminium and tungsten. Lead and iron have least conductivity i.e., they offer very high resistance to the flow of current.

Question 4.
Which property of metals give them characteristic chemical properties?
Answer:
Metals form positive ions by loosing electrons. This property of formation of ions by the metals give them characteristics chemical properties, e.g., Mg form Mg ion by loosing two electrons :
Mg → Mg²⁺ + 2e^–

Question 5.
Ionic compounds are found in which state? Comment on the melting and boiling point of ionic compounds.
Answer:
Compounds which are formed by the transfer of electrons from metals to Non¬Metals are called ionic or electrovalent compounds e.g., NaCl, LiCl, CaCl₂, CaO, MgCl₂. Ionic compounds have very high melting and boiling points because a large amount of energy is required to break the strong inter-ionic attractions.

Question 6.
What is difference between minerals and ores?
Answer:

Sr. No. Minerals	Ores
1. Those natural occuring substances, which contain metals in the form of compounds.	1. These are the minerals from which metals can be extracted easily and cheaply.
2. In many of the minerals percent age amount of metals is large and in some it is less.	2. In all the ores, percentage amount of metals is enough.
3. In some minerals there are so many impurities which create difficulty in the extraction of metals.	3. Ores do not have such problematic impurities.
4. All the minerals can not be used for extracting metals. All the minerals are not ores.	4.         All the ores can be used to extract metals.

Question 7.
How are the metals extracted, which are at the top of reactivity series?
Answer:
Metals which are towards the top of reactivity series are sodium, calcium, magnesium, aluminium. There are very reactive. These metals can not be obtained by heating them with carbon. These have more affinity towards oxygen, therefore these are extracted by electrolytic reduction. Sodium, magnesium and calcium are obtained by the electrolysis of their molten chlorides. Metals got deposited at cathode and chorine is liberated at anode.
At cathode : Na⁺ + e^– → Na
At anode : 2Cl^– → Cl₂ + 2e^–

Aluminium is obtained by the electrolytic reduction of aluminium oxide.
At cathode ; Al³⁺ + 3e^– → Al

Question 8.
How the metals, which are in the middle of the activity series extracted?
Answer:
Metals which are in the middle of the activity series are iron, zinc, lead, copper etc. These are found in the form of sulphides or carbonates. It is easy to obtain metals from their oxides compared to sulphides or carbonates. Therefore before extraction metal sulphide or carbonates are converted into their oxide. Sulphide ores are converted into metal oxides by heating in the presence of air. This is known as roasting. Carbonate ores are heated in limited supply of air to convert them into oxides. This is known as calcination. Following reactions take place during roasting and calcination of zinc.


Then by using carbon as reducing agent, metal is extracted from metal oxide, e.g. when Zinc oxide is heated with carbon it gets reduced to give zinc.

In addition to using carbon for reduction, displacement reaction can be used to extract metals. More reactive metals like sodium, calcium, aluminium etc. can be used as reducing agents because these can displace atoms which are below them in the reactivity series. For example, when mangnese dioxide is heated with aluminium powder then following reaction takes place.

Question 9.
How will you extract metals which are low in the activity series?
Answer:Metals low in the activity series are less reactive and can be obtained from metal oxides simply by heating. Cinnabar (Hgs) an ore of mercury (Hg) when heated change to mercuric oxide (HgO), on heating it further it is reduced to mercury.

Question 10.
Explain the reactions of metals with water.
Answer:
On reacting with water, metals form metal oxide and produce hydrogen. These dissolve in water to form metal hydroxide. But all metals do not react with water.

Metals like sodium and Potassium react with cold water, vigorously. The reaction of sodium and Potassium is very vigorous and exothermic that hydrogen produced starts burning simultaneously.
2K (s) + 2H₂O (l) → 2KOH (aq) + H₂(g) + heat
2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂(g) + heat

Reaction of calcium with water is slow. Heat produced in this reaction is not enough to burn the hydrogen produced in the reaction.
Ca (s) + 2H₂O(l) → Ca (OH)₂ + H₂(g)

Metals like iron, aluminium, zinc etc. do not react with cold water and not even with hot water. But they react with steam to form metal oxide and produce, hydrogen.
2Al(s) + 3H₂O(g) → Al₂O₃(S) + 3H₂(g)
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
Metals like lead, copper, silver and gold etc. do not react with water.

Question 11.
How do metals react with :
1. Oxygen
2. Dilute acids
3. Chlorine
4. Hydrogen.
Answer:
I. Reaction of metals with oxygen: Metals combine with oxygen to form metal oxides. Metal atoms lose their loosely bound electrons to form positive ions where as oxygen atoms gain electrons to form negative oxide ions. These metal oxide are basic in nature. Since all metals have different level of reactivity therefore they combine with oxygen at different temperatures.
1. Na and K Combine with oxygen at normal temperature to form oxides which dissolve in water to form hydroxide.
4 Na (s) + O₂(g) → 2Na₂S(s)
Na₂O(s) + H₂O → 2NaOH (or)

2. If magnesium is burned in air it forms magnesium oxide.
Mg → Mg²⁺ + 2e-
O + 2e^– → O^2-
Mg²⁺ + O^2- → MgO

3. Copper and iron combine with oxygen at high temperature in dry air.

II. Reaction of metals with dilute acids. Metals reacts with dilute acids to produce hydrogen gas. Rate of reactivity is different.
1. Na, K, Zn, Mg, Fe etc. are reactive in decreasing order.
2Na + HCl → 2NaCl + H₂ ↑
Mg + 2HCl → MgCl₂ + H₂↑
Zn + H2SO₄ → ZnSO₄ + H₂↑

2. Dilute nitric acid reacts with metals like Cu, Ag, Pb, Hg to form NO (nitrogen oxide).
Cu + 8HNO₃ → 3Cu (NO₃)₂ + 2NO + 4H₂O
3Ag + 4HNO₃ → 3AgNO₃ + NO + 2H₂O

3. Dilute nitric acid reacts with Mg and Mn to produce hydrogen gas.
Mg + 2HNO₃ → Mg (NO₃)₂ + H₂ ↑

4. Gold and platinum do not react with dilute acids.

III. Reaction of metals with chlorine. Metals combines with chlorine to form electrovalent chlorides.
Ca + Cl₂ → CaCl₂

IV. Reaction of metals with hydrogen. Reactive metals like Na, K, Ca etc. react with hydrogen to form hydrid.
2Na + H₂ → 2NaH
Ca + H₂ → CaH₂

V. Reaction of metals with water:
1. Water at normal temperature react with Na, K and Ca to liberate hydrogen gas.
2Na + 2H₂O → 2NaOH + H₂ ↑
Ca + 2H₂O → Ca (OH)₂ + H₂ ↑

2. Mg, Zn and Fe react with boiling water to form oxide.
Mg + H₂O → MgO + H₂ ↑
3Fe + 4H₂O → Fe₃O₄ + 4H₂ ↑

Question 12.
What is roasting? When do you use it?
Answer:
Roasting. After enrichment of ore, it is heated in the presence of dir, this process is called roasting sulphides or carbonates of some metals are converted into oxides, because extraction of metal is easy from oxides. Carbonates and sulphides of zinc and lead are converted into oxides by roasting.

Question 13.
If a copper plate remains immersed in silver nitrate solution for some time then what happens? Write the ionic equation for the reaction.
Answer:
Copper is more reactive than silver. Copper will displace silver from the solution and silver gets deposited on copper. Colour of the solution becomes blue.

Question 14.
Copper sulphate solution is stored in an iron container. After some days holes were seen in the container. Write the reaction. Explain the reaction on the basis of activity series.
Answer:
Iron is more reactive than copper and is placed before copper in the activity series. Therefore iron can displace copper from copper sulphate solution, due to this reaction holes were seen in the container.
CuSO₄ + Fe → FeSO₄ + Cu
Cu²⁺ (aq) + Fe(s) → Fe²⁺ (aq) + Cu(s)
Thus iron displaced copper.

Question 15.
Why copper becomes green if left open in air. Why?
Answer:
Copper reacts with moist carbon dioxide which is present in air. This makes its surface dull and a green layer is seen on the surface of copper. This green substance is copper carbonate.

Question 16.
What is 24 carat gold?
Answer:
Pure gold is called 24 carat gold. It is very soft. It can be used to make ornaments. Small amount of silver or copper is mixed with it to make it harder. In our country usually 22 carat gold is used to make ornaments. This means 22 pure gold is mixed with 2 parts of copper or silver.

Question 17.
Which process is used for the enrichment of sulphide ore. Explain in brief two steps involved in the extraction of metal from enriched sulphide ore.
Answer:
Sulphide ore is finely grounded to get powder. This is then enriched by using ‘Froth floation process’.

Steps involved in the extraction of metal from enriched sulphide ore :
1. Roasting: Enriched ore is heated in the presence of air to get oxides. This process is called roasting.

2. Reduction. Oxide of the enriched ore is heated with reducing agent to extract the metal.

Question 18.
Give differences :
(i) Hydraulic washing and liquation.
Answer:

Hydraulic Washing	Liquation
1. This process is used for concentration of an ore.	1. The process is used for refining of metals.
2. Ore is washed with washing.	2. This is used for refining metal having low melting points.

(ii) Electrolytic reduction and reduction by carbon.
Answer:

Electrolytic reduction	Reduction by carbon
1. Here cathode acts as reducing agent. It converts metal ions into metals by providing electrons.	Carbon is used as reducing agent.
2. This method is used to reduce the salts of highly reactive metals.	2. This method is used to reduce the oxides of metals which are in the middle of activity series.

Question 19.
An alloy of yellow’ colour is made up of two metals A and B. When this alloy was dipped in dilute sulphuric acid, a layer dissolved in acid and formed colourless solution. B did not dissolve in it and the surface of alloy attained red brown colour. What is A and B?
Answer:
Yellow coloured alloy is brass which is mixture of zinc and copper. In this A is zinc and B is copper.
Zn + H₂SO₄ → ZnSO₄ + H₂

Question 20.
Sulphur dioxide (SO₂) gas is produced when a certain ore is heated. Write the method involved in the extraction of metal from this ore.
Answer:
SO₂ gas is produced when copper pyrites an ore of copper is heated.

Following steps are involved in the extraction of metal from this ore :
1. Ore is ground to get powder. It is mixed with water and pine oil. Compressed air is blown to separate impurities. This way ore gets enriched, this method is called froth floatation method.

2. Now the enriched ore is roasted. A part of CuS converts to CuO

Copper is in liquid state and is purified by electric refining.

3. Electrical refining. In this process impure copper rod is taken as anode and pure copper plate is taken as cathode. Electric current is passed through copper sulphate solution in the presence of acid

Question 21.
What is Thermite process? Write its uses.
Answer:
Some displacement reactions are highly exothermic. The quantity of heat produced is so high that metals obtained are in molten state. When Iron (III) oxide (Fe₂O₃) reacts with aluminium then a large amount of heat is produced.
Fe₂O₃(s) + 2Al(s) → 2Fe(l) + Al₂O₃(s) + heat

This is known as thermite process. This process is used to weld the rails and to join the cracks in machines.

Question 22.
Give five uses of non-metals.
Answer:

• Hydrogen is used in the preparation of vegetable oil.
• Carbon is an important non-metal which is main constituent of vitamins, proteins, carbohydrates, enzymes etc. Graphite is used as an electrode in various cells.
• Nitrogen is used in ammonia, Nitric acid and fertilizers. Its presence in air controls the rate of combustion.
• Presence of oxygen is the base of our life. Combustion is also possible in the presence of oxygen.
• Sulphur is used in many medicines and is also used to make explosives.

Question 23.
Differentiate Roasting and Calcination.
Answer:

Roasting	Calcination
1. Roasting is used for sulphide ores.	1. Calcination is used for carbonate and hydrated ores.
2. Ore is heated in the presence of air.	2. Ore is heated in the absence of air.
3. SO2 gas is produced.	3. CO2 gas is produced.

Question 24.
How is ionic compound sodium chloride, forms from sodium and chlorine?
Answer:
Sodium and chloride ions are oppositely charged and thus attract each other
They are bound together by strong electrostatic force of attraction and exist in the form of sodium chloride (NaCl). Sodium chloride does not exist as a molecule but as a set of ions :

Question 25.
Ionic compounds are insulators when in solid state whereas when in aqueous solution they become conductors. Why?
Answer:
There exist a strong force of attraction between positive and negative ions of the ionic compounds, due to which these compounds are solid and hard. Due to their firm and rigid structure ions cannot move. But in molten state or in aqueous solution the force between opposite ions become weak and the ions can move freely. Therefore electricity can pass through ionic compounds when in liquid form.

Question 26.
What is aqua regia? Explain.
Answer:
Aqua regia is a mixutre of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3 : 1. It can dissolve gold where no single acid can do this. Aqua regia (Latin word for Royal water) is highly corrosive and fuming liquid. It can also dissolve platinum.

Question 27.
Give two main ores of aluminium. Also give two alloys of aluminium.
Answer:
Two ores of aluminium are :

1. Bauxite, Al₂O₃. 2H₂O
2. Cryolite, Na₃ (AlF₆).

Two alloys of aluminium are :

1. Duralium
2. Magnalium.

Question 28.
Give uses of pure metals.
Answer:

• Copper and aluminium wires are used in the transmission of power (electricity).
• Utensils, Machines etc. are made up of iron, aluminium and copper.
• Gold and silver are used to make ornaments, these are also used in sweets in the form of silver foil.
• Metals like cadmium, titanium, zinconium etc. are used in nuclear energy and space science projects.
• Aluminium foil is used to wrap eatables.
• Titanium and its alloys are used in airplane, airplane structure and engine, chemical reactor.
• Metals are used in broken bones and body parts.

Question 29.
Which gas is produced, when reactive metals come in contact with dilute hydrochloric acid? Write the chemical reaction between iron and dil. H₂SO₄.
Answer:
When reactive metals come in contact with dil. hydrochloric acid then (H₂) hydrogen gas is produced.
Hydrogen gas is produced when iron reacts with dil. H₂SO₄.
Fe + H₂SO₄ → FeSO₄ + H₂ ↑

Question 30.
What is the function of cryolite in the electrolytic reduction of alumina?
Answer:
Cryolite has two functions in the extraction of aluminium :

• To reduce the melting point of alumina.
• Alumina is bad conductor of electricity on mixing cryolite (Na₂AlF₃), Al²⁺ ions are produced from alumina.

Question 31.
How do iron and aluminium react with water?
Answer:
Aluminium and iron do not react with cold or hot water. But react with steam to form metal oxide and hydrogen.
2Al(s) + 3H₂O(g) → Al₂O₃(s) + 3H₂(g)
3Fe(s) + 3H₂O(g) → Fe₃O₄(s) + 3H₂(g)

Question 32.
What happen when :
(i) Iron oxide is heated with coke?
Answer:
Iron oxide is readuced to iron.

(ii) Magnesium is treated with dilute sulphuric acid?
Answer:
Hydrogen is produced

(iii) Zinc is added to blue vitriol solution?
Answer:
Blue colour of solution gradually faders away

Question 33.
What is rust? Explain it with the help of a chemical reaction.
Answer:
If iron is left open in moist air, a brown layer is produced on its surface. This brown coloured layer is of Ferric oxide and ferric hydroxide. This is called rust. This makes iron weak.
4Fe + 3O₂ + 3H₂O → Fe₂O₃ + 2Fe(OH)₃

Question 34.
Write names of main alloys and their constituents?
Answer:

Alloys	Constituents	Uses
1. Steel	Iron, carbon	used in airplanes, buildings vehicles etc.
2. Stainless steel	Iron, Carbon, Chromium	utensils, machine parts, knife, blade, food and milk industry, nuts, bolts, taps etc.
3. Brass	Copper, Zinc	utensils, idols, airplanes, medals, steam driven train parts etc.
4. Bronze	Copper, tin	utensils and other apparatus.
5. Solder	Lead, tin	For joining/welding electric wires.
6. German Silver	Copper, Nickel, zinc	Airplane wings, utensils used in kitchen of airplanes and other mate­rials.
7. Bell metal	Copper,tin	For making bells.
8. Duralium	Aluminium, copper magnesium and mangnese in very small amount.	In airplane
9. Magnoleum	Aluminium, magnesium	Light weight tools and cheap utensils.
10. Gun metal	Copper, tin, zinc	For making gears of vehicles and machines.

Question 35.
Write the names of metals found in Bronze and Duralium, give uses of these alloys.
Answer:
Bronze. It is 90% copper and 10% tin. It is used in idols, medals, coins and vessels used for cooking food.
Duralium. It consists of 95% aluminium, 4% copper, 0.5% magnesium and 0.5% manganese. It is used in aeroplanes, space crafts, kitchen vessels.

Question 36.
What is rust? What is its chemical formula?
Answer:
When iron is left open in air, then a layer of iron oxide is formed on the surface of iron. This brown matter is rust. It corrodes the metal. Its chemical formula is Fe₂O₃. xH₂O.

Question 37.
What are metals?
Answer:
The elements which are on the left and in the middle of the periodic table and have metallic lustre are called metals. These are usually ductile, malleable, good conductor of electricity and heat, hard and have high density. They form basic oxides. Examples of metals are gold, iron, silver, copper, platinum etc.

Question 38.
What is ihe reason of catching fire by potassium and sodium on their own?
Answer:
Potassium and sodium reacts with water vigorously and violently. The reaction is very violent and highly exothermic that hydrogen produced in the reaction catches fire on its own.

Question 39.
Observe the figure given below and name the gas produced. Also give the chemical equation.

Answer:
Hydrogen gas is produced

Question 40.
What is indicated by the following figure?
Or
With the help of a labelled diagram prove that both oxygen/air and water are necessary for rusting of iron.

Answer:
Both air and moisture are required for rusting of iron.

Question 41.
Why the substance obtained by mixing small amount of carbon in iron is used largely for various purposes?
Answer:
When small amount of carbon is mixed with iron it changes to steel. This is stronger than iron. It can be used in ships, vehicles, dams.

Question 42.
Write a chemical equation for the reaction taking place in the test tube. How does the colour of solution change? What is change in colour of iron nails?

Answer:

The colour of the solution changes from blue to light green. The colour of Iron nails changes from grey to brown.

Very Short Answer Type Questions

Question 1.
Give one example of metal which is liquid at room temperature.
Answer:
Mercury.

Question 2.
Name one metal and one non-metal which is liquid at room temperature.
Answer:
Metal-Mercury.
Non-Metal—Bromine

Question 3.
Name one non-metal which has bright lustre.
Answer:
Iodine.

Question 4.
Name one non-metal which does not have bright.
Answer:
Phosphorus.

Question 5.
Which of the following metal are liquid at body temperature (37° C): Gallium, Magnesium, Caesium, Aluminium.
Answer:
Gallium and Caesium.

Question 6.
Name one non-metal which is a good conductor of electricity?
Answer:
Graphite (Carbon).

Question 7.
Arrange the following metals in the decreasing order of reactivity,
Fe, Zn, Cu, Na, Ag.
Answer:
Na > Zn > Fe > Cu > Ag.

Question 8.
Out of Sodium, Calcium, Aluminium, Copper and Magnesium name the metal which reacts with
(i) Boiling water
Answer:
Magnesium

(ii) Steam.
Answer:
Copper.

Question 9.
Sodium metal is kept under kerosene oil, why?
Answer:
This is because sodium reacts with moist air as well as water.

Question 10.
A non-metal X, exists in two forms Y and Z. Y is the hardest substance and Z is a poor conductor of electricity. What are X, Y and Z?
Answer:
Y = Diamond Z = Graphite X = Carbon
Y and Z are allotropic forms of carbon.

Question 11.
An element, A form two oxides AO and AOa. AO is neutral and AO₂ is acidic : Indicate whether A is metal or non-metal.
Answer:
A is non-metal.

Question 12.
Name the reaction to convert metal into its oxide .
Answer:
Oxidation.

Question 13.
Ionic solids have high melting points, why?
Answer:
In ionic solids, there are strong electrostatic forces of attraction between the oppositely charged ions and a large amount of energy required to overcome these forces.

Question 14.
An element X reacts with oxide to form oxide, X₂O which dissolves in water and turns red litmus solution blue. Give the nature of oxide and indicate X is metal or non-metal.
Answer:
X₂O is basic. X is metal.

Question 15.
What is the nature of metal oxides?
Answer:
Basic.

Question 16.
Name two noble metals.
Answer:
Gold and platinum.

Question 17.
Name an ore of mercury.
Answer:
Mercury sulphide (Hgs).

Question 18.
Name two metalloids.
Answer:
Arsenic, antimony.

Question 19.
Metals lose lustre when placed in air, why?
Answer:
This is because their surfaces are covered with oxides, carbonates or sulphide layer’s .

Question 20.
Name two metals which can be cut with a knife.
Answer:
Sodium and potassium.

Question 21.
Why do metals aquire different shapes?
Answer:
This is due to malleability and ductility of metals.

Question 22.
Name the metal which is poor conductor of heat.
Answer:
Lead.

Question 23.
Name the metal which offers resistance to the flow of electricity.
Answer:
Mercury.

Question 24.
Which of the following metals can be drawn into wires?
Answer:
Cu, Al, Fe, Pb.

Question 25.
Name four non-metals which are solid at room temperature.
Answer:
Carbon, Sulphur, Phosphorous, and iodine.

Question 26.
Name the elements which are present in abundance in earth’s crust.
Answer:
Oxygen and silicon.

Question 27.
What are alkalies? Give one example.
Answer:
Alkali. It is a metal hydroxide soluble in water Example : Sodium hydroxide (NaOH).

Question 28.
Name two amphoteric oxide.
Answer:

1. Aluminium oxide (Al₂O₃)
2. Zinc Oxide (ZnO)

Question 29.
What happens when magnesium is heated to ignition temperature?
Answer:
Magnesium burns with white light producing magnesium oxide.

Question 30.
Name the metal which does not react with dil. HCl.
Answer:
Copper.

Question 31.
Name two metals which react with hydrogen.
Answer:
Sodium and potasium.

Question 32.
Give the reaction when a piece of Calcium reacts with water.
Answer:
Ca + 2H₂O → Ca (OH)₂ + 4H₂.

Question 33.
Give the reactions when red hot iron reacts with steam.
Answer:
Ca + 4H₂O → Fe₃O₄ + H₂.

Question 34.
Why is zinc oxide called amphoteric oxide?
Answer:
This is because zinc oxide reacts with both acid as well as base.

Question 35.
The metals Na, K and Ca react with hydrogen to form hydroxide but other metals don’t, why?
Answer:
This is because Na, K and Ca are highly reactive metals.

Question 36.
Give the reactions which occur when zinc plate is added to copper sulphate solution.
Answer:
Zn + CuSO₄ → ZnSO₄ + Cu.

Question 37.
Out of the metals, Na, Cu, Au, which is
(i) Most reactive and
Answer:
Most reactive metal-Sodium (Na)

(ii) Least reactive?
Answer:
Least reactive metal-Gold (Au).

Question 38.
Arrange the following metals in the decreasing order of reactivity, Zinc, Mercury and Aluminium.
Answer:
Al < Zn < Hg.

Question 39.
Name two metals which occur in free state in nature.
Answer:
Gold and Platinum.

Question 40.
Define corrosion of metals.
Answer:
It is the interaction of surface of metal with air and moisture forming a layer of oxide, halide or carbonate layer on its surface.

Question 41.
Name a metal which undergoes corrosion in air.
Answer:
Iron.

Question 42.
Name two metals which are not corroded easily.
Answer:
Gold and silver.

Question 43.
Why does copper utensils turn green on exposure to air?
Answer:
Copper reacts with oxygen, carbon dioxide and moisture to form a green coloured compound (basic copper carlxmate):

Question 44.
Name two metals which are both malleable and ductile.
Answer:

1. Copper
2. Aluminium.

Question 45.
Name the most abundant metal in the earth’s crust.
Answer:
Aluminium.

Question 46.
Name the metal that gives a green coating when exposed to moisture.
Answer:
Copper.

Question 47.
Which is the most lightest metal known to us?
Answer:
Lithium.

Question 48.
Name two metals which occur in free state in nature.
Answer:

1. Gold
2. Platinum.

Question 49.
Name one of the most common ore of aluminium.
Answer:
Bauxite (Al₂O₃. 2H₂O).

Question 50.
What is an amalgam?
Answer:
An amalgam is an alloy of mercury with some other metals.

Question 51.
Name two metals which :
(a) readily burn in air an
Answer:
Metals which readily burn in air are :

1. sodium
2. magnesium.

(b) do not burn.
Answer:
metals which do not burn readily in air are :

1. Copper
2. iron.

Question 52.
Name the metal which is best conductor of electricity.
Answer:
Silver.

Question 53.
Name one metal which reacts with cold water.
Answer:
Sodium.

Question 54.
Name one metal
(i) more reactive than hydrogen and
Answer:
Sodium

(ii) less reactive than hydrogen.
Answer:
Silver.

Question 55.
Write the chemical name of any one compound ore of sulphur.
Answer:
Zinc sulphide (ZnS).

Question 56.
Name the metal used in galvanisation of iron.
Answer:
Zinc.

Question 57.
The metal which is found in nature in the free state is
Answer:
Gold and Platinum.

Question 58.
What chemical process is used for obtaining a metal from its oxide?
Answer:
Reduction process.

Question 59.
Which metals do not corrode easily?
Answer:
The metals which are not attacked by air and moisture don’t corrode easily.

Multiple Choice Questions :

Question 1.
The non-metal which is liquid at room temperature is:
(A) Chlorine
(B) Bromine
(C) Fluorine
(D) Iodine.
Answer:
(B) Bromine

Question 2.
Most reactive metal is:
(A) Na
(B) Mg
(C) Au
(D) K
Answer:
(D) K

Question 3.
The property due to which metals can be beaten into sheets is :
(A) Malleability
(B) Ductility
(C) Metallic lustre
(D) Hardness.
Answer:
(A) Malleability

Question 4.
The axnphoteric oxide is:
(A) ZnO
(B) BaO
(C) K2O
(D) Na2O.
Answer:
(A) ZnO

Question 5.
Copper gets covered with green layer when exposed to air due to the formation of:
(A) CuSO₄
(B) CuCO₃. Cu(OH)₂
(C) Cu (NO₃)₂
(D) CuO.
Answer:
(B) CuCO₃. Cu(OH)₂

Question 6.
During galvanisation, the metal whose layer is deposited is:
(A) Gallium
(B) Aluminium
(C) Zinc
(D) Silver.
Answer:
(C) Zinc

Fill in the blanks:

Question 1.
Brass is an alloy of copper and ____________
Answer:
Zinc.

Question 2.
____________ is the best conductor of electricity.
Answer:
Silver.

Question 3.
All the ores are ____________
Answer:
Minerals.

Question 4.
Copper can be refined by ____________
Answer:
Electrorefining.

Punjab State Board PSEB 10th Class Science Book Solutions Chapter 3 Metals and Non-metals Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Science Chapter 3 Metals and Non-metals

PSEB 10th Class Science Guide Acids, Bases and Salts Textbook Questions and Answers

Question 1.
Which of the following pairs will give displacement reactions :
(а) NaCl solution and copper metal
(b) MgCl₂ solution and aluminium metal
(c) FeSO₄ solution and silver metal
(d) AgNO₃ solution and copper metal?
Answer:
(d) AgNO₃ solution and copper metal?

Question 2.
Which of the following methods is suitable for preventing an iron frying pan from rusting :
(a) applying grease
(b) applying paint
(c) applying a coating of zinc
(d) all of the above :
Answer:
(c) applying a coating of zinc

Question 3.
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be :
(a) calcium
(b) carbon
(c) silicon
(d) iron.
Answer:
(a) calcium

Question 4.
Food cans are coated with tin and not with zinc because :
(а) zinc is costlier than tin
(b) zinc has a higher melting point than tin
(c) zinc is more reactive than tin
(d) zinc is less reactive than tin.
Answer:
(c) zinc is more reactive than tin

Question 5.
You are given a hammer, a battery, a bulb, wires and a switch.
(i) How could you use them to distinguish between samples of metals and non-metals?
(ii) Assess the usefulness of these tests in distinguishing between metals and non-metals.
Answer:
(i) Set up the electric circuit as shown below :

To distinguish between metals and non-metals on the basis of their electrical conductivity.

Insert the sample to be tested between clips A and B
If the bulbs glows, the sample is metal.
If the bulb does not glow, the sample is non-metal.
Thus metals are good conductors of electricity whereas non-metals are poor conductors of electricity.

(ii) If a substance produces a sound when struck beating with a hammer, it is a metal and if no sound is produced, it is a non-metal.
Metals are sonorous whereas non-metals are non-sonorous.

Question 6.
What are amphoteric oxides? Give two examples of amphoteric oxides.
Answer:
Amphoteric oxides. The metal oxide which react both with acids as well as bases to produce salts and water are known as amphoteric oxides.

Examples. Zinc oxide, ZnO Aluminium oxide, Al2O3

Question 7.
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer:
Zinc and magnesium can displace hydrogen from dilute acids. Copper and silver cannot displace hydrogen from dilute acids.

Question 8.
In the electrolytic refining a metal M, what would you take as the anode, the cathode and the electrolyte?
Answer:
During the electrorefining of metal, the impure metal is made as anode, a thin strip of pure metal M is made as cathode. The electrolyte used a soluble salt of metal M. to be refined.

Question 9.
Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it as shown in figure

Collection of Gas
(a) What will be the action of gas on
(i) dry litmus paper?
Answer:
No action.

(ii) moist litmus paper?
Answer:
It turns moist litmus paper red and then bleaches it.

(b) Write a balanced chemical equation for the reaction taking place.
Answer:
S + O₂ → SO₂

Question 10.
State two ways to prevent the rusting of iron.
Answer:
The rusting can be prevented by

1. By painting, oiling, greasing, galvanising, chrome plate or anodising.
2. By forming alloys.

Question 11.
What type of oxides are formed when non-metals combine with oxygen?
Answer:
As they form two types of oxides :
(a) Neutral oxides such as CO, NO etc.
(b) Acidic oxides such as SO₂, CO₂ etc.

Question 12.
Give reasons :
(a) Platinum, gold and silver are used to make jewellery.
Answer:
Platinum, gold and silver are used to make jewellery because these are not attacked by air and moisture. They don’t undergo corrosion and retain their lustre for a long time. Also these metals are malleable and ductile.

(b) Sodium, potassium and lithium are stored under oil.
Answer:
Sodium, potassium and lithium are stored under oil because in contact with moist air containing carbon dioxide, these are covered with a carbonate layer.
e.g. 4Na + O₂ → 2Na₂O
Na₂O + H₂O → 2NaOH
2NaOH + CO₂ → Na₂CO₃ + H₂O

Also they react with water.
e.g. 2Na + 2H₂O → 2NaOH + H₂.
Hence, these metals are stored under oil.

(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
Answer:
This is due to the reason that a thin sticking oxide layer of aluminium is formed on its surface which prevents further reaction. Also aluminium is a good conductor of heat and the oxide layer (Al₂O₃) is stable even at high temperatures.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
Answer:
This is because it is easier to obtain a metal from its oxide as compared to its sulphide and carbonate ore.

Question 13.
You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
Answer:
In tarnished copper vessel there is a layer of basic copper carbonate. This basic layer can be cleaned by using sour substances such as lemon or tamarind juice which are acidic in nature and dissolve the basic coat of copper carbonate

Question 14.
Differentiate betw een metals and non-metals.
Or
Differentiate between metals and non-metals on the basis of their chemical properties.
Answer:
Differences between metals and non-metals :

Metals	Non-Metals
1. They form basic oxides.	1. They form acidic or neutral oxides.
2. They displace hydrogen from dilute acids.	2. They don’t displace hydrogen from dilute acids.
3. Usually they don’t combine with hydrogen. Only a few reactive metals combine with hydrogen to form metal hydroxide which are electrovalent compounds.	3. They react with hydrogen to form hydrides which are covalent compounds.
4. They form chlorides which are electrovalent compounds.	4. They react with chlorine to form chlorides which are covalent compounds.

Question 15.
A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Answer:
The solution used by goldsmith to bring back the glitter of old and dull gold ornaments was aqua regia. It is a freshly prepared mixture of cone. HCl and cone. HNOg in the ratio 3 : 1. It can dissolve gold,

Question 16.
Give the reasons why copper is used to make hot water tanks but steel (an alloy of iron) is not.
Answer:
This is because iron present in steel reacts with steam to form ferrosoferric oxide whereas copper has no action with water. As a result of it, the body of the steel tank becomes weaker and weaker in case of iron and not in case of copper.

Science Guide for Class 10 PSEB Metals and Non-metals InText Questions and Answers

Question 1.
Give an example of a metal which :
(i) is a liquid at room temperature
Answer:
Mercury

(ii) can be easily cut with a knife
Answer:
Sodium

(iii) it is the best conductor of heat
Answer:
Silver

(iv) is a poor conductor of heat.
Answer:
Lead.

Question 2.
Explain the meaning of malleable and ductile.
Answer:
Malleable: A substance is said to be malleable, if it can be beaten into sheets. e.g. metals are malleable.
Ductile: A substance is said to be ductile, if it can be drawn into wires e.g. the metals are ductile.

Question 3.
Why is sodium kept immersed in kerosene oil?
Answer:
This is because in contact with moist air containing carbon dioxide, it is covered with a carbonate layer.
4Na + O₂ → 2Na₂O
Na₂O + H₂O → 2NaOH
2NaOH + CO₂ → Na₂CO₃ + H₂O

Also sodium reacts with water.
2Na + 2H₂O → 2NaOH + H₂
Hence, sodium is kept immersed in kerosene oil.

Question 4.
Write equation for the reactions of
(i) iron with steam
Answer:

(ii) calcium and potassium with water.
Answer:
Ca + 2H₂O → Ca(OH)₂ + H₂
2K + 2H₂O → 2KOH + H₂

Question 5.
Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows :

Use the table above to answer the following questions about metals, A, B, C and D.
(i) Which is the most reactive metal?
Answer:
B is the most reactive metal.

(ii) What would you observe if B is added to a solution of copper (II) sulphate?
Answer:
B will displace copper from copper sulphate solution.

(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.
Answer:
The decreasing order of reactivity is B > A > C > D.

Question 6.
Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H₂SO₄.
Answer:
Hydrogen gas is produced when dilute hydrochloric acid is added to a reactive metal.

Question 7.
What would you observe when zinc is added to a solution of iron (II) sulphate? Write the chemical reaction that takes place.
Answer:
When zinc is added to a solution of iron (II) sulphate it will displace iron from it and light green colour of solution gradually fades away.

Question 8.
(i) Write the electron-dot structures for sodium, oxygen and magnesium.
Answer:
Electron-dot structures for sodium, oxygen and magnesium are

(ii) Show the formation of Na₂O and MgO by the transfer of electrons.
Answer:
Formation of Na₂O:

(iii) What are the ions present in the above compounds?
Answer:

Question 9.
Why do ionic compounds have high melting points?
Answer:
In ionic compounds there are strong electrostatic forces of attraction between oppositely charged ion and a considerable amount of energy is required to break the strong interionic attraction.

Question 10.
Define the terms :
(a) mineral
Answer:
Mineral. The compounds of elements occurring in earth’s crust which are associated with earthly impurities are called minerals.

(b) ore
Answer:
Ore. An ore is a mineral from which metal can be extracted conveniently and economically.

(c) gangue.
Answer
Gangue. The earthly impurities such as sand, lime stone, rocks etc. associated with minerals and ores are collectively known as gangue or matrix.

Question 11.
Name two metals which are found in nature in the free state.
Answer:
Gold and Platinum.

Question 12.
What chemical process is used for obtaining a metal from its oxide?
Answer:
Reduction process.

Question 13.
Metallic oxides of zinc, magnesium and copper were heated with the following metals :

Metal	Zinc	Magnesium	Copper
Zinc oxide
Magnesium oxide
Copper oxide

In which cases will you find displacement reactions taking place?
Answer:
Zinc can displace copper from copper oxide

Magnesium can displace zinc from zinc oxide

Also Mg can displace copper from CuO

Question 14.
Which metals do not corrode easily?
Answer:
The metals which are not attacked by air and moisture don’t corrode easily.

Question 15.
What are alloys?
Answer:
Alloys. These are the homogeneous mixtures of two or more metals or metals and non-metals.

Punjab State Board PSEB 10th Class English Book Solutions English Vocabulary Idioms Exercise Questions and Answers, Notes.

PSEB 10th Class English Vocabulary Idioms

I. Use the following idioms in sentences of your own :

1. Off and on
2. In the air
3. To come to light
4. Call it a day
5. In a nutshell
6. Early bird
7. To go to the dogs
8. Cry wolf
9. Down to earth
10. To end in smoke
11. Tooth and nail
12. Hat-trick
Answer:
1. Off and on– Our principal addresses the students off and on
2. In the air — Corruption is in the air all over the country.
3. To come to light – Many strange facts came to light during course of enquiry.
4. Call it a day — It is very late now; we should call it a day.
5. In a nutshell – He explained everything to me in a nutshell.
6. Early bird — He is an early bird. He goes for a morning walk every day.
7. To go to the dogs — Without discipline, any organisation go to the dogs.
8. Cry wolf — Do not trust him. He is in the habit of crying wolf.
9. Down to earth — His down to earth proposal attracted immediate attention.
10. To end in smoke — All my efforts to reform him have ended in smoke
11. Tooth and nail — We shall oppose corruption tooth and nails
12. Hat-trick — Which Indian bowler performed a Hat-trick m the last World Cup?

II. Match the idioms in column A with their meanings in column B :

A — B
1. hard and fast — (a) in detail
2. ill at ease — (b) to happen
3. go up in flames — (c) to bribe
4. to lose face — (d) to blame
5. to foot the bill — (e) rigid
6. to find fault with — (f) uncomfortable
7. to grease the palm — (g) to pay the bill
8. to come to pass — (h) to be destroyed
9. on the cards — to lose prestige
10. at length : — (j) probable
Answer:
1. — (e) 2. — (f) 3. — (h) 4. – (i) 5. — (g) 6. — (d) 7. —(C) 8. — (b) 9. (j) 10. — (a)

शब्दों के ऐसे समूह को idiom या मुहावरा कहा जाता है जिसका अर्थ उसके अलग-अलग शब्दों से स्पष्ट न हो, अपितु पूरे समूह को ही याद करना और उसके अर्थ को जानना होता हो। इस तरह के कुछ शब्द – समूह (idioms) नीचे दिए जा रहे है

1. Above board
This shopkeeper is above board in his dealings.

2. Adam’s ale
Adam’s ale is very necessary for good health.

3. An eyewash
This enquiry is only an eyewash; nothing will come out of it.

4. At par
Death treats the rich and the poor at par.

5. In the air
Terrorism is in the air all over the world.

6. All in all
Our father is all in all in our family.

7. At a discount
They are selling everything at a discount.

8. Apple of one’s eye
The only son was the apple of his parents’ eye.

9. Apple of discord
Kashmir has become an apple of discord between India and Pakistan.

10. All Greek
He spoke in English which was all Greek to the villagers.

11. At a stretch
She can speak for hours at a stretch. At a low
Morality is at a low ebb these days.

13. As easy as ABC
Mathematics for me is not difficult. It is as easy as ABC.

14. Again and again
I have warned him again and again, but he does not care.

15. All of a sudden
He got up all of a sudden and left the room.

16. At large
Her killer is still at large.

17. At length
He talked about his problem at length.

18. Behind one’s back
You should not abuse him behind his back.

19. A bed of roses
Life is not a bed of roses for the poor.

20. Borrowed plums
Borrowed plums don’t make one rich in the real sense.

21. Blue blood
Princess Diana was never proud of her blue blood.

22. A bosom friend
Is he your bosom friend ?

23. To beat about the bush
Do not beat about the bush; come to the point.

24. By virtue of
She got the job by virtue of her greater experience.

25. By leaps and bounds
Our school is progressing by leaps and bounds under the present principal.

26. On the cards
It is on the cards that Indian cricket team will win the World Cup this time.

27. To carry the day
Indian team carried the day against Pakistani team.

28. A cat and dog life
He has been living a cat and dog life with his wife.

29. To call a spade a spade
I have no fear and always call a spade a spade.

30. A clean state
After her divorce she started her life with a clean state.

31. A close shave
They had a close shave in the car accident last night.

32. A cock and bull story
He made up a cock and bull story for being absent.

33. To come to light
During the enquiry, many new facts have come to light.

34. To come to pass
All that you told me has come to pass.

35. Crocodile tears
The wicked wife shed crocodile tears over the death of her husband.

36. Call it a day
After playing for his country for ten years, he decided to call it a day.

37. Call the shots
It is the manager who calls the shots in our company.

38. Charity begins at home
For all politicians these days, charity begins at home.

39. Clear the deck
The Principal asked the students to clear the deck for the welcome of the Chief Guest at the Annual Function of the school.

40. Close-fisted person
He is a close-fisted person and won’t give you any money.

41. Coin money
He is coining money from his new business.

42. Cut one’s coat according to one’s cloth
If you don’t want to get into debt, always cut your coat according to your cloth.

43. Dark horse
The lean and thin boy proved a dark horse when he won the long-distance race.

44. To go to the dogs
His business has gone to the dogs and his family is starving.

45. Down to earth
My approach to life is always down to earth.

46. A dead language
Sanskrit is now a dead language.

47. Die by inches
The poor old man died by inches.

48. Do a good turn
Try to do a good turn every day.

49. To give ear
Give ear to what I am saying.

50. To make both ends meet
It is very difficult for the poor to make both ends meet these days.

51. To end in smoke
All my efforts to reform him have ended in smoke.

52. An eye-opener
You should take your failure as an eye-opener.

53. Now start working hard. Early bird
She is an early bird and goes for a morning walk.

54. To lose face
As a result of his mistakes, he has lost face in his office.

55. To save face
She was dismissed, but she saved face by telling everyone that she had resigned.

56. Face-to-face
I came face-to-face with a burglar when I opened the door of my house.

57. To find fault with
We should not find fault with others.

58. With flying colours
Those who work hard always come off with flying colours in their exams.

59. To foot the bill
Who will foot the bill of this party ?

60. Tooth and nail
We shall oppose the new taxes tooth and nail.

61. To gain ground
Madhuri is gaining ground in her popularity day-by-day.

62. To throw out of gear
Life was thrown out of gear because of the floods.

63. To grind one’s teeth
She grinds her teeth when she is asleep.

64. To grease the palm
In India, you can have anything done by greasing the palm.

65. Go up in flames
The whole house went up in flames with a cracker.

66. A hen-pecked husband
He is a hen-pecked husband; his wife leads him by the nose.

67. A Herculean task
It is a Herculean task to bring up one’s children these days.

68. To lay hands on
No one can dare to lay hands on our soil.

69. To take heart
He took heart, tried again, and was successful.

70. To take to one’s heels
On seeing the policeman, the thief took to his heels.

71. Hard and fast
There are no hard and fast rules of reading a book.

72. To hush up
The minister tried to hush up the bad acts of his son.

73. Ins and outs
He quickly learnt all the ins and outs of his father’s business.

74. Ill at ease
Phatik felt ill at ease at his uncle’s house.

75. To keep an eye on
We requested our neighbours to keep an eye on our house while we were away.

76. To look sharp
Look sharp, or you will miss the train.

77. In a nutshell
Tell me the whole story in a nutshell.

78. To cry over spilt milk
It is no use crying over spilt milk.

Punjab State Board PSEB 10th Class English Book Solutions English Vocabulary Pairs of Words Generally Confused Exercise Questions and Answers, Notes.

PSEB 10th Class English Vocabulary Pairs of Words Generally Confused

Choose the correct word for each blank.

1. He went for a walk in the ………..(wood, woods)
2. She always ……………. good clothes. (wares, wears)
3. Please …………… here for some time. (wait, weight)
4. Bad …………….. of drugs was soon felt. (affect, effect)
5. He was set free on …………….. (bale, bail)
6. Can you ……………… this stick ? (break, brake)
7. ……. off your old shoes. (Caste, Cast)
8. Lata is my ………………. friend.(dear, deer)
9. He does not …… good clothes (wear, ware)
10. The child wanted me to tell a …………(tail, tale)
11. I …………….. whose house is this ! (wander, wonder)
12. He felt .. ……………. after illness. (weak, week)
13. Do not go out in bad ……. (weather, whether)
14. She gave …………….. to a baby girl. (birth, berth)
15. He noted it down in his (diary, dairy)
16. He is opening the garden …………… (gate, gait)
17. If a man is not …………….. he can hardly expect to succeed. (industrious, industrial)
18. He fell a ………………. to disease. (pray, prey)
19. Newton formulated the …………… of gravitation.(principal, principle)
20. He wanted to …………….. an educated girl. (marry, merry)
21. Make a list of all the ……………… members in our staff. (male, mail)
22. She never lost her …………… (tamper, temper)
23. ……………… out the damp clothes. (Ring, Wring)
24. He is in the ……………… of smoking after meals. (custom, habit)
25. Do not ……………… in the class. (doze, dose)
Answer:
1. woods
2. wears
3. wait
4. effect
5. bail
6. break
7. Cast
8. dear
9. wear
10. tale
11. wonder
12. weak
13. weather
14. birth
15. diary
16. gate
17. industrious
18. prey
19. principle
20. marry
21. male
22. temper
23. Wring
24. habit
25. doze.

अंग्रेजी भाषा के कुछ शब्द प्रायः विद्यार्थियों के मन में उलझन पैदा कर देते हैं क्योंकि कई बार वे बोलने में एक जैसे प्रतीत होते हैं, किन्तु उनके अर्थ एक-दूसरे से बहुत भिन्न होते हैं। इस तरह के शब्दों के अर्थ और उनके प्रयोग विद्यार्थियों को अच्छी तरह से समझ लेने चाहिएं। ऐसे कुछ उदाहरण प्रयोग सहित नीचे दिए जा रहे हैं।

1. Accept – He accepted my offer.
Except – All except Mohan were present.

2. Alter – Don’t alter your decision now.
Altar – He bowed his head at the altar.

3. Adapt – You should adapt yourself to new system.
Adopt – Rajni says she will adopt this child.
Adept – She is adept in painting.

4. Access – I have no access to the minister.
Excess – Excess of everything is bad.

5. Advise – He advised me to work hard.
Advice – I shall follow your advice.

6. Angle – Make an angle of 30°.
Angel – Gandhiji was an angel of peace.

7. Incident – It was a sad incident of my life.
Accident – He was killed in a bus accident.

8. Amiable – She has an amiable nature.
Amicable – They reached an amicable settlement.

9. Affect – Overwork affected her health.
Effect – My advice had no effect on him.

10. Artisan – A blacksmith is an artisan.
Artist – A singer is an artist.

11. Bail – He was released on bail.
Bale – I bought two bales of cotton.

12. Bare – Don’t walk around in bare feet.
Bear  – I can’t bear this insult.

13. Battle – Our army won the battle.
War – The world is living in the fear of war.

14. Born – When were you born?
Borne – I have borne many difficulties.

15. Bridal – She has gone for bridal make-up.
Bridle – Can you bridle this horse?

16. Birth – What is your date of birth?
Berth – I got a berth in the train.

17. Break – You shouldn’t break the rules.
Brake – The brakes of my bike don’t work.

18. Canon – It is against the canons of morality.
Cannon – He was killed by a cannon ball.

19. Canvas – He is good at canvas painting.
Canvass – He was canvassing for votes.

20. Carrier – My bicycle has no carrier.
Career – He was successful in his career.

21. Cast – Cast off your old dress.
Caste – He is a Brahmin by caste.

22. Childish – I don’t like her childish ways.
Childlike – Your childlike simplicity is in fact your beauty.

23. Cite – He cited an example to prove his point.
Site – This site is good for a factory.
Sight – The sight of the hills was very lovely.

24. Cord – I want a piece of cord to hang this picture.
Chord – A chord joins two points on a circle.

25. Course – The question paper was out of course.
Coarse – This cloth is very coarse.

26. Custom – The dowry is a bad custom.
Habit – Smoking is a bad habit.

27. Check – The teacher checked my homework:
Cheque – I gave her a cheque for one thousand rupees.

28. Council – He is a member of the students council.
Counsel – Listen to the counsel of your elders.

29. Dear – Arun is my dear friend.
Deer – A deer can run very fast.

30. Dose – Take your dose of medicine.
Doze – He was dozing in the class.

31. Discover – America was discovered by Columbus.
Invent – Who invented telephone?

32. Disease – Is Diabetes not a serious disease?
Decease – After her father’s decease, she joined the family business.

33. Drown – The boy was drowned in the river.
Sink – The boat sank in the flooded river.

34. Due – This loss was due to your carelessness.
Dew – The dew drops looked very beautiful.

35. Dying – The old man was dying.
Dyeing – He has a dyeing factory

36. Diary – Diary writing is a good habit.
Dairy – We buy milk from a dairy.

37. Envelop – He was enveloped blanket.
Envelope – She received a letter with a torn envelope.

38. Fair – Our prices are always fair.
Fare – Children travel half fare.

39. Feet – I have pain in my feet.
Feat – The magician showed us many feats.

40. Farther – I am tired and can’t go any farther.
Further – Have you any further questions?

41. Flour – The bread is made of flour.
Floor – There was a carpet on the floor.

42. Fore – There was fire in the fore part of the ship.
Four – Two and two make four.

43. Foul – Never play a foul game.
Fowl – The goose is a water fowl.

44. Forth – They set forth at dawn.
Fourth – She got the fourth position.

45. Farm – Mr. Gill has a very big farm.
Form – Please help me fill in this form.

46. Gate – This big building has an iron gate.
Gait – She has a lovely gait.

47. Goal – What is your goal in life?
Gaol – The thief was sent to gaol.

48. Hail – He hails from Delhi.
Hale – He looked hale and hearty.

49. Heel – I have pain in my left heel.
Heal – Your wound will take time to heal.

50. Human – To err is human.
Humane – She has a very humane nature.

51. Hair – She has very long hair.
Hare – The hare can run very fast.

52. Idle – Don’t sit idle…
Idol – Sachin is the idol of many cricket lovers.

53. Industrial – Ludhiana is an industrial town.
Industrious – Punjabis are industrious people.

54. Loose – I like loose clothes.
Lose – Be brave and don’t lose heart.

55. Lesson – I have learnt my lesson.
Lessen – This tablet will lessen your pain.

56. Loin – Let us gird up our loins.
Lion – He is as brave as a lion.

57. Liar – He is a liar by nature.
Lawyer – His father is a lawyer.

58. Mail – I received a letter by mail.
Male – She has one male child.

59. Miner – Seven miners were killed in the accident.
Minor – It is not a minor mistake.

60. Merry – Eat, drink and be merry.
Marry – She doesn’t want to marry.

61. Meet – I meet him almost daily.
Meat – I do not eat meat.

62. Pail – The pail is full of water.
Pale – She turned pale at the sight of a thief in the house.

63. Pain – I have pain in my head.
Pane – Who has broken the window-pane ?

64. Pair – I have bought a pair of shoes.
Pare – Pare your nails.

65. Piece – I gave him a piece of bread.
Peace – We want to live in peace.

66. Practice – Practice makes a man perfect.
Practise – You should practise every day.

67. Quite – I am feeling quite well today,
Quiet – Keep quiet, please.

68. Pray – I pray to God daily.
Prey – The lion is a beast of prey.

69. Principal – The principal of our school is a gentle person.
Principle – He is a man of high principles.

70. Right – He is right in saying this.
Rite – Old rites must go now.
Write – She writes to me off and on.

71. Route – We took the shortest route.
Rout – The enemy was put to rout.

72. Role – She played her role nicely.
Roll – The teacher took the roll.

73. Ring – She was wearing a gold ring.
Wring – Wring out the towel, please.

74. Sale – This house is for sale.
Sail – The ship was in full sail.

75. Sore – My eyes are sore.
Sour – These grapes are sour.
Soar – Prices are soaring these days.

76. Soul – The soul is immortal.
Sole – The sole of my shoe needs mending.

77. Stationary – The sun is stationary.
Stationery – He deals in stationery.

78. Steal – Knowledge is a thing that none can steal.
Steel – The knife is made of steel.

79. Story – He told us a false story.
Storey – This house has three storeys.

80. Son – His son is a doctor.
Sun – The sun gives us light and heat.

81. Tail – A monkey has a long tail.
Tale – She related her sad tale.

82. Their – They have finished their work.
There – We waited there for an hour.

83. Throne – The king was sitting on his throne.
Thrown – Rotten eggs were thrown away.

84. Tamper – Someone has tampered with my books.
Temper – Do not lose your temper.

85. Vacation – We went to Shimla during the summer vacation.
Vocation – Nursing is a noble vocation.

86. Waste – Don’t waste your time. e
Waist – I have pain in my waist.

87. Weak – The old man was too weak to walk.
Week – He is coming here next week.

88. Wonder – I wonder what he wants.
Wander – He keeps wandering all day.

89. Whet – Hard work whets the appetite.
Wet – Don’t wear these wet clothes.

90. Weather – The weather was fine on the hills.
Whether – I want to know whether he will come.

91. Weight – What is your weight ?
Wait – I had to wait for a long time.

92. Ware – He goes from street to street selling his wares.
Wear – She loves to wear loose clothes.

93. Wood – This chair is made of wood.
Woods – He left home and went to live in the woods.

94. Which – Which class are you in ?
Witch – I don’t believe in ghosts and witches.

Punjab State Board PSEB 10th Class Agriculture Book Solutions Chapter 7 Contribution of Agriculture in Economic Development Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Agriculture Chapter 7 Contribution of Agriculture in Economic Development

Agriculture Guide for Class 10 PSEB Contribution of Agriculture in Economic Development Textbook Questions and Answers

(A) Answer in one-two words:

Question 1.
How much population of our country lives in villages?
Answer:
More than two-third.

Question 2.
What proportion of labour force in India is dependent directly on agriculture?
Answer:
54%.

Question 3.
What is the contribution of agriculture in gross domestic product in the country?
Answer:
According to 2012-13 data it was 13.7%.

Question 4.
How much food grains were produced in 1950-51 and how much did it increase to in 2013-14?
Answer:
It was 51 million ton in 1950-51, which was 264 million ton in 2013-14.

Question 5.
Which are the three sectors of Indian economy?
Answer:
Agriculture, Industry and service sector.

Question 6.
Where does India stand in foreign trade?
Answer:
Tenth.

Question 7.
Which country has been left behind by India in the field of rice export?
Answer:
Thailand.

Question 8.
Name the major industries dependent for raft material on agriculture.
Answer:
Textile industry, sugar industry, jute industry.

Question 9.
In which year the Food Security Act was passed?
Answer:
In the year 2013.

Question 10.
What is India’s agricultural balance of trade?
Answer:
According to 2013-14, balance of trade was surplus by 25 billion dollar.

(B) Answer in one-two sentences:

Question 1.
How agricultural development is linked with dependence of population on agriculture?
Answer:
Dependence of people on agriculture helps in good growth and development of economy. As the economy of country develops, dependence on agriculture automatically decreases.

Question 2.
What are the main agricultural exports of India?
Answer:
Cotton, pulses, oil, fruits, tea, coffee, vegetables, cashew, spices, rice, wheat etc.

Question 3.
What are the main agricultural imports of India?
Answer:
Pulses, oil seed, dry fruits, edible oil etc.

Question 4.
Name a few agricultural based enterprises. Or Write the name of any four agriculture based enterprises.
Answer:
Dairy farming, poultry farming, fish farming, piggry, animal husbandry, fish farming, agroforestry etc. are some agricultural based enterprises.

Question 5.
Why a buffer stock of food grains in the country is maintained?
Answer:
This is done to control the rise in prices in case of inflation in future under the fear of fall in supply. Needy families are provided with foodgrains every month from this stock under Public Distribution System (PDS).

Question 6.
What are the main provisions of Food Security Act, passed by Govt of India in year 2013?
Answer:
The main provisions of the food security act is to provide 5 kg of grains per kg per month to 75% rural population and to 25% urban population.

Question 7.
How development of railways is linked to the agricultural development?
Answer:
Railways are used to transport agricultural produce from one part of the country to other parts of country and this way department of railways get income and this helps in the expansion and development of railways.

Question 8.
Name the industries which depend upon agriculture for marketing of their products. Or Write name of four agro-based industries.
Answer:
Tractor, agricultural implements, fertilizers, weedicides, insecticides etc. are used in agricultural sector. Those industries which manufacture them or produce them depend on agriculture sector for marketing these products.

Question 9.
What type of unemployment do we find in agriculture?
Answer:
Unemployment found in agriculture sector is seasonal and .hidden or disguised unemployment.

Question 10.
What are the benefits of allied activities of agriculture?
Answer:
Allied activities of agriculture are helpful to farmers in the sense these fulfil their daily needs by providing them with better and nutritious diet and also as source of extra income, e.g. milk, eggs, meat, fish, honey etc. are the products which they obtained from these allied activity, consume market and sell these and this helps in adding to their income also.

(C) Answer in five-six sentences

Question 1.
What is the contribution of agriculture in economic development of India?
Answer:
Nearly two-third population of our country depends on agriculture and 54% of the labour force directly depend on agriculture. GDP of the nation from agriculture was 13.7% in the year 2012-13. Several industries are based on agriculture e.g. sugar, jute and textile industries. Products from many industries are used in agriculture.

Transportation, godowns, warehouses add to the economy of the country. Several agricultural products are exported and country gain in terms of dollars. Due to export of agricultural products central government gain from export duty. State government earns from land taxes and also from irrigation. Marketing fees also adds to the government treasury. Agriculture adds to the economy of the country.

Question 2.
What is the significance of agriculture in India’s foreign trade?
Answer:
Foreign trade of India is very deeply dependent on agriculture. Several agriculture products are imported e.g. tea, coffee, spices, oil, cotton, fruits, vegetables, pulses, cashew and now wheat and rice,also. In 2012, India was at the top in the export of rice by leaving behind-Thailand. India is at 10th place in export of grains in the world. Some materials like cotton fibre, yam, readymade cloth, jute products etc. are also exported. In year 2013-14 gross export of agricultural products was 42 billion dollar and in the same year import was of 17 billion dollar. This way India’s balance of trade was surplus by 25 billion dollar.

Question 3.
What were the main reasons of Green Revolution in the country?
Answer:
After the independence of India, for many decades we remained dependent on other countries for grain. Hard work of farmers of India, researched by scientists, improved seeds, agricultural implements, fertilizers, pesticides etc. helped in bringing green revolution. Grain production became so large that now we export wheat, rice and other agricultural products.

Question 4.
Why the pressure on agriculture should be reduced in India? Give reasons.
Answer:
Large proportion of our population depends on agriculture. Nearly 54% of labour force is directly engaged in agriculture sector. An economy can develop and grow in a better way if we can reduce our dependence on agriculture. Seasonal and hidden unemployment is found in agricultural sector it is necessary to provide some other jobs to such workers. As the economy of the country grows, dependence on agriculture decreases automatically and dependence on industry and services sector increases.

Question 5.
How does agricultural and industrial growth depend on each other?
Answer:
If agriculture develops and grows in a country, then various types I of agriculture produces are available in large quantities. There is need to establish various industries for the processing and consumption of these produces. Some parts of our country where these products are not available, these are transported to such parts of the country. The excess grains are stored in warehouses.

Some of the industries based on agriculture are sugar industry, jute industry, shellar, oil extracting industry etc. This way agriculture development helps in the growth of industry. But for sustained agricultural development, some other products and implements etc. are needed in the agriculture sector. Products from various industries e.g. tractor industry, machinery, fertilizers, pesticide and other chemicals etc. are used in agriculture sector. This way industrial development is related to agriculture development.

PSEB 10th Class Agriculture Guide Contribution of Agriculture in Economic Development Important Questions and Answers

Multiple Choice Questions

Question 1.
During the year 2012-13, share for GDP from agriculture sector was:
(a) 13.7%
(b) 15.9%
(c) 11.5%
(d) None.
Answer:
(a) 13.7%

Question 2.
Grain production in India during 2013-14 was:
(a) 264 million ton
(b) 51 million ton
(c) 100 million ton
(d) None.
Answer:
(a) 264 million ton

Question 3.
Main agricultural exports of India:
(a) tea
(b) cotton
(c) pulses
(d) All.
Answer:
(d) All.

Question 4.
Which country has been left behind by the India in the field of rice export?
(a) Thailand
(b) Bhutan
(c) America
(d) Sri Lanka.
Answer:
(a) Thailand

Question 5.
In 2012 buffer stock of food grain was-
(a) 82 million ton
(b) 25 million ton
(c) 52 million ton
(d) 108 million ton
Answer:
(a) 82 million ton

Question 6.
Under provision of Food Security Act-2013, how much grain to be alloted per person per month?
(a) 5 kg
(b) 10 kg
(c) 15 kg
(d) 20 kg.
Answer:
(a) 5 kg

True or False:

1. Many industries get, their raw material from agriculture.
Answer:
True

2. In the year 2012, India got first position in the export of rice leaving behind Thailand.
Answer:
True

3. There is seasonal and disguised unemployment in the field of agriculture.
Answer:
True

4. India’s gross agricultural exports stood at 42 billion dollar in 2013-14.
Answer:
True

5. The yield of food grains increased to about 2125 kg per hectare.
Answer:
True.

Fill in the blanks:

1 is considered to be back bone of Indian economy.
Answer:
Agriculture

2. India is now placed at number in import of agricultural produce and food grains in the world.
Answer:
Ten

3. In the year 2012, our country had a buffer stock of tones of food grains.
Answer:
82 million

4. About of the households are engaged in dairy farming in India.
Answer:
70 million.

Very Short Answer Type Questions

Question 1.
What is agriculture for our country?
Answer:
Back bone of our economy.

Question 2.
How much population is involved in the occupation for dairy farming in our country?
Answer:
70 million families.

Question 3.
Which of the sectors come under the service sectors?
Answer:
Banking services, transportation, storage and warehouses, insurance, tourism etc.

Question 4.
What is the place of our country in the world on the basis of population?
Answer:
2nd place.

Question 5.
How much percentage in household consumption is from agriculture?
Answer:
60%.

Question 6.
What is the yield of grains?
Answer:
2125 kg per hectare.

Question 7.
How much was the stock of grains in the country in the year 2012?
Answer:
82 million tons.

Question 8.
How much wheat would be supplied at a subsidized rate to feed to 82 crores of population every year?
Answer:
61 million ton.

Question 9.
In export of which agriculture product India remained at top in year 2012?
Answer:
Rice.

Question 10.
How much was the total agricultural export in the year 2013-14?
Answer:
42 billion dollar.

Question 11.
How many percent of workers in India are directly engaged in agriculture?
Answer:
50% workers.

Short Answer Type Questions

Question 1.
Which are the small scale industries based on agriculture?
Answer:
Small scale industries based on agriculture are-rice shellar, oil extraction etc.

Question 2.
Which is the third sector of economy? Give example.
Answer:
Third sector is service sector in economy, e.g. Banking services, transportation, warehouses, insurance sector, tourism etc.

Long Answer Type Questions

Question 1.
Country has become self-dependent in the production of grains. Explain by comparison.
Answer:
In the year 1950-51, food grain production was 51 million ton which in the year 2013-14 became 264 million tons. Grain yield has also increased and is approximately 2125 kg per hectare. In the year 2012 country had 82 million ton of food grains in the buffer stock which itself is a record. This shows that country has become self-dependent.

Question 2.
Write any five reasons for the green revolution in the country?
Answer:

• Increased availability and ease of sources of irrigation.
• The use of fertilizers helped in obtaining higher yields.
• Discovery and use of high-yielding varieties.
• Protection of crops against diseases, weeds, and insects became easy.
• Increased use of Agri machinery.

Question 3.
Write any four reasons for the green revolution in India.
Answer:
Do yourself.

Punjab State Board PSEB 10th Class Agriculture Book Solutions Chapter 6 Agroforestry Textbook Exercise Questions and Answers.

PSEB Solutions for Class 10 Agriculture Chapter 6 Agroforestry

Agriculture Guide for Class 10 PSEB Agroforestry Textbook Questions and Answers

(A) Answer in one-two words:

Question 1.
How much area should under forests in Punjab, as per National Forest Policy 1988?
Answer:
20%.

Question 2.
How much area is under forests and tree cover in Punjab?
Answer:
6.49%.

Question 3.
How many major agro climatic zones are there in Punjab on the basis of climate?
Answer:
Three.

Question 4.
In which season acute shortage of fodder is felt in Kandi region of Punjab?
Answer:
In winter.

Question 5.
What is the spacing for planting of poplar on boundary of a field?
Answer:
3 metres.

Question 6.
What types of .soils are there in Kandi region?
Answer:
Soil is undulating that is not uniformly levelled. It has many ups and down.

Question 7.
Name two trees used for fodder in Kandi region.
Answer:
Dhak, Beri, Chhal, Kachnar etc.

Question 8.
What should be the pH of soil for poplar cultivation?
Answer:
6.5 to 8.0.

Question 9.
Name the trees suitable for commercial agroforestry in Punjab.
Answer:
Poplar, Eucalyptus

Question 10.
How many Poplar plants are planted in per hectare?
Answer:
200 trees per acre.

(B) Answer in one-two sentences:

Question 1.
What is the planting time of Poplar in Punjab?
Answer:
Suitable time for planting poplar in Punjab is January-February.

Question 2.
Define Agroforestry.
Answer:
Agroforestry is a land management system in which cultivation of trees and crops is done together in a field along with rearing of animals on the same piece of land.

Question 3.
What type of soil and irrigation facilities are available in Central plain zone in Punjab?
Answer:
In this zone, soil is fertile and irrigation facilities are available here.

Question 4.
What type of trees are found in S-W region of Punjab?
Answer:
Kikar, Tahli, Mango, Dhrek, Nim, Jamun, Toot etc. trees are planted in south-western zone.

Question 5.
Write down planting and spacing requirements of Eucalyptus.
Answer:
Cuttings are used for the propagation of Eucalyptus. Eucalyptus can be planted on the boundaries of the field or in block plantation. Plant to plant spacing on the boundaries should be 2 metres and if planted in block plantation the spacing should be 4 x 2 m.

Question 6.
Write the clones of poplar planted in Punjab.
Answer:
PL-1, PL-2, PL-3, PL-4, PL-5, L-47/88, L-48/89 are clones of poplar.

Question 7.
What is the planting time of Eucalyptus in Punjab?
Answer:
Eucalyptus can be planted in March-April and July-August.

Question 8.
Write down the names of the industries where poplar wood is used.
Answer:
Wood obtained from poplar can be used in Match box industry, ply manufacturing, packing cases etc.

Question 9.
What is the spacing for poplar planting?
Answer:
If poplar is planted on boundaries then plant spacing should be 3 metre and if it is planted in die whole field then spacing should be 8 x 2.5 m or 5 x4m.

Question 10.
Write the name of trees grown in Kandi region.
Answer:
Toot, Nim, Tahli, khair, Kikkar, Bel, Kachnar, Mango, Subabaul, Aijun, Harar, Behra, Phalis and dhak, Dehrek, Sohanjana etc.

(C) Answer in Jive-six sentences:

Question 1.
Write down the clones planted and spacing for poplar planting in Punjab. .
Answer:
PL-1, PL-2, PL-3, PL-4, PL-5, L-47/88, L^18/89 are some of the clones of poplar. If poplar is planted on boundaries then plant spacing should be 3 metre and if it in planted is the whole field then spacing should be 8 x 2.5 m or 5 x 4 m. 200 plants per acre can be planted in the field.

Question 2.
Write down the source of clonal Eucalyptus plants in Punjab.
Answer:
We should plant Eucalyptus plants prepared from cuttings in Agroforestry. These all grow uniformely. These can be obtained from any nursery of department of forests and wildlife preservation, Punjab, PAU, Ludhiana or any other private registered nursery.

Question 3.
How poplar can be planted?
Answer:
Make a pit which is 3 feet deep and have diameter of 15-20 cm. Use chloropyriphos and Emisan-6 against termies and diseases. Plant poplar trees in the month of January and February. Water the plants immediately after planting the poplar tree. If poplar is planted on boundaries then plants spacing should be 3 metre and if it in planted in the whole field then spacing should be 8 x 2.5 m or 5 x 4 m. 200 plants per acre can be planted in the fields.

Question 4.
Where poplar wood is used?
Answer:
Cultivation of poplar is helpful in creating employment and also in small enterprises in which wood is the raw-material. Poplar is used in various industries e.g. it is used in the manufacturing of match sticks. It is also used in the manufacture of plywood and also in the packaging industry to make boxes. This way one can earn by the cultivation of poplar. It sheds off its leaves in winter thus has no harm for Rabi crops.

Question 5.
Why Poplar and Eucalyptus are suitable for commercial Agroforestry? Or Why are Eucalyptus and poplar cultivated as commercial agro forestry in Punjab?
Answer:
Poplar and Eudalyptus are suitable for commercial agroforestry in Punjab. Wood obtained from these trees can be easily marketed. The income from these trees in more than wheat-rice cropping system.

Safeda:
It grows in less time, stem is straight, its branches shed off regularly. Its wood is used as building material, its pulp is used in paper industry, wooden beams are also obtained from it. Therefore it is suitable for cultivation in agroforestry.

Poplar:
It provides employement. Its wood is used in small scale industry; like, ply, match sticks, packing boxes etc. It also does not affect the Rabi crops.

PSEB 10th Class Agriculture Guide Agroforestry Important Questions and Answers

Multiple Choice Questions

Question 1.
According to National Forest Policy 1988, forests should occupy of area in plain states.
(a) 5%
(b) 20%
(c) 50%
(d) 29%.
Answer:
(b) 20%

Question 2.
In central plain region trees are grown.
(a) Poplar
(b) Dek
(c) Eucalyptus
(d) All
Answer:
(d) All

Question 3.
………….. is not a variety of poplar:
(a) PL-5
(b) PL-47/88
(c) PL-858
(d) PL-48/89.
Answer:
(b) PL-47/88

Question 4.
Poplar trees become ready in years for harvesting.
(a) 5 to 7
(b) 1 to 2
(c) 10 to 12
(d) 15 to 25.
Answer:
(a) 5 to 7

Question 5.
pH value for soil for poplar cultivation.
(a) 10
(b) 6.5 to 8.0
(c) 3 to 4
(d) 4 to 5.5.
Answer:
(b) 6.5 to 8.0

Question 6.
In which direction the trees are planted on ridges of the farms for agro forestry?
(a) North-South
(b) East-west
(c) South-east
(d) North-east.
Answer:
(a) North-South

Question 7.
For timber production after how many years Eucalyptus can be harvested?
(a) 13 to 15 years
(b) 6 to 8 years
(c) 4 to 6 years
(d) 2 to 4 years.
Answer:
(a) 13 to 15 years

Question 8.
For batten production, after how many years Eucalyptus can be harvested?
(a) 13 to 15 years
(b) 6 to 8 years
(c) 4 to 6 years
(d) 2 to 4 years.
Answer:
(c) 4 to 6 years

Question 9.
For paper pulp production, after how many years Eucalyptus can be harvested?
(a) 13 to 15 years
(b) 6 to 8 years
(c) 4 to 6 years
(d) 2 to 4 years.
Answer:
(b) 6 to 8 years

True False:

1. Poplar is more successful in Bet area.
Answer:
True

2. Poplar tree become ready for harvesting after 5-7 years.
Answer:
True

3. To save orchards from wild life, Jatropha are grown around the orchards.
Answer:
True

4. Poplar cultivation is successful in Kallar and water logged soils.
Answer:
False

5. Eucalyptus clonal plants should be planted in Agroforestry.
Answer:
False

Fill in the blanks:

1. Poplar wood is used in the manufacture of ……………. .
Answer:
Match sticks

2. For boundaries poplar trees are planted at spacing.
Answer:
3 m

3. …………….. erosion is major problem in sub-mountainous zone.
Answer:
Soil

4. Pl-3 is a …………….. clone.
Answer:
poplar

5. In winter the scarcity of ……………. is felt in submountaneous zone.
Answer:
fodder.

Very Short Answer Type Questions

Question 1.
Why is agroforestry suitable for Punjab?
Answer:
It helps in increasing the area under the forests and trees.

Question 2.
Can we take income from agroforestry?
Answer:
Yes, more than the conventional agricultural practices i.e. more than paddy-wheat cropping system.

Question 3.
In which direction, trees should be planted on the boundaries of fields? (PS.E.B. 2017)
Answer:
In North-South direction.

Question 4.
In how many zones is Punjab divided on the basis of climate?
Answer:
Three zones.

Question 5.
On what basis the farmer in Kandi area grow their crops?
Answer:
Agriculture is based on the rainfall.

Question 6.
Which of the trees are planted to save the orchards?
Answer:
Jatroffa, Karonda, Ipomea.

Question 7.
What type of soil is found in south-western zone?
Answer:
Saline and alkaline soil.

Question 8.
Poplar is not harmful for rabi crops, how?
Answer:
Its leaves shed off in winter and it is not harmful for rabi crops.

Question 9.
What type of soil is not suitable for poplar?
Answer:
Kallar and water-logged.

Question 10.
In which area poplar is must successful?
Answer:
In bet area.

Question 11.
How many poplar trees can be planted in the field?
Answer:
200 trees per acre.

Question 12.
In how many years poplar trees are ready?
Answer:
5 to 7 years.

Question 13.
What type of Eucalyptus plants should be planted?
Answer:
Prepared from cuttings.

Question 14.
How many Eucalyptus plants are planted In the whole field?
Answer:
500 trees per acre.

Question 15.
If Eucalyptus cultivation is for long time, what should be row spacing?
Answer:
8 metre.

Question 16.
After how many years can we get wood for buildings (timber) from Eucalyptus?
Answer:
13 to 15 years.

Question 17.
After how many years is Eucalyptus ready for pulp?
Answer:
6 to 8 years.

Question 18.
After how many years Eucalyptus is ready for battens?
Answer:
4 to 6 years.

Question 19.
Write file name of two trees which are mainly grown in Punjab for commercial agroforestry.
Answer:
Poplar, Eucatyplus.

Short Answer Type Questions

Question 1.
Write the name bf two main models for agroforestry?
Answer:
There are two main models for agroforestry-Boundary plantation and intercropping in block plantation.

Question 2.
Where do farmers plant trees if they use boundary plantation model?
Answer:
They plant trees on the boundaries of fields.

Question 3.
Which of the trees are used for planting on the boundaries?
Answer:
Subabaul, Drek, Toot, Eucalyptus, Poplar, Siris, Lassora, Sohanjana, Nim, Tahli etc. –

Question 4.
Which farmers do the mixed farming of crops and trees?
Answer:
Those farmers who have more agricultural land can do mixed farming.

Question 5.
Which of the trees are suitable for planting in the whole field?
Answer:
Poplar, Eucalyptus, Dhrek and Tun are suitable trees.

Question 6.
In which area is the problem of soil erosion found?
Answer:
Soil found in the Kandi area is not uniform and land has many ups and downs (undulating) therefore problem of soil erosion is also found there.

Question 7.
Which type of soil is suitable for poplar?
Answer:
Well drained, loamy to sandy, fertile soil and which have pH value from 6.5 to 8.0 is suitable for growing popular.

Question 8.
List four uses of wood of Eucalyptus.
Answer:
Batten, pulp, wood used in buildings construction, industry, furniture

Question 9.
Write the name of four trees which are grown in whole field in agroforestry.
Answer:
Poplar, Eucalyptus, Toon, Dhrek.

Question 10.
Why salinity is found in the upper surface of the soil in the South-Western zone?
Answer:
Water under the earth in this zone is saline. This makes upper surface of the soil also saline.

Long Answer Type Questions

Question 1.
Write about trimming and pruning of poplar? Or Write the benefit of correctly pruning poplar plants at the right time.
Answer:
There is no need of trimming in the first year, but in the second year after shedding off the leaves there is a need of pruning of the trees to make it straight and to give it good appearance. If trimming and pruning is done at proper time then the stem remains straight and without nodes.

Question 2.
Which of the qualities of Eucalyptus make it suitable for cultivation in agroforestry? Or For which qualities Eucalyptus is grown in agroforestry?
Answer:
It grows in less time, stem is straight, its branches shed off regularly. Its wood is used as building material, its pulp i§, used in paper industry, wooden beams are also obtained from it. Therefore it is suitable for cultivation in agroforestry.

Question 3.
Define Agroforestry.
Answer:
According to National Forest Policy 1988, to fulfil the needs based on wood and to keep the environment safe, area under the forests should be 20%. But it is not possible to increase the area under the forests therefore this is achieved by agroforestry. Agroforestry is the cultivation of trees and crops together in the same field. The objective behind this, type of cultivation is that farmers can fulfil their needs e.g. cereals, wood, fuel, fodder and also can save the natural resources e.g. soil, water, air etc. There is also an increase in their income.

Question 4.
What do you mean by agroforestry? Explain in detail about the planting trees on farm boundaries in agroforestry.
Answer:
Do it yourself.