PSEB 7th Class Science Solutions Chapter 9 Soil

Punjab State Board PSEB 7th Class Science Book Solutions Chapter 9 Soil Textbook Exercise Questions and Answers.

PSEB Solutions for Class 7 Science Chapter 9 Soil

Science Guide for Class 7 PSEB Soil Intext Questions and Answers

Think and Answer (Textbook Page No. 103)

Question 1.
What is the chemical nature of the soil having pH is 3 ?
Answer:
The chemical nature of soil with pH value is acidic.

Question 2.
What is the chemical nature of soil having pH 10 ?
Answer:
Soil with pH value of 10 is alkaline.

Question 3.
Write down the pH of neutral soil.
Answer:
Neutral soils have pH of 7.

Think and Answer (Textbook Page No. 104)

Question 1.
In which type of soil rate of percolation is highest ?
Answer:
Sandy soils have the highest water leaching (leakage) rate.

Question 2.
Which soil has maximum water retention capacity ?
Answer:
Clay by soil has the highest water retention capacity.

Think and Answer (Textbook Page No. 106)

Question 1.
Why is soil tilled or ploughed ?
Answer:
Soil is ploughed to make the soil loose and porous.

Question 2.
What is the use of air present in soil ?
Answer:
The roots of the plants use the air present in the soil.

PSEB 7th Class Science Guide Soil Textbook Questions and Answers

1. Fill in the Blanks:

(i) The top layer of earth upto a depth of 30-40 cm where crops can grow is called ………………..
Answer:
Soil

(ii) A section of earth shows …………………. of soil.
Answer:
Layers

(iii) Acidic nature or alkaline nature of soil can be tested by using a …………………. .
Answer:
pH paper

(iv) ………………… has the finest particles which can even pass through muslin cloth.
Answer:
Clayey soil

(v) ………………. soil has least water retention capacity.
Answer:
sand

(vi) ……………….. soil is best for growing crops.
Answer:
Loamy and clayey

(vii) In western states of India like Gujarat and Maharashtra, the soil is of ………………… colour.
Answer:
Black

(viii) ………………… is used by potters for making earthen pots.
Answer:
Clay

(ix) The soil which is used for making cement is ………………….. .
Answer:
Clayey soil

(x) Bricks are made from ………………….. .
Answer:
sandy soil

2. State True or False:

(i) pH paper is used to test the acidic or alkaline nature of soil.
Answer:
True

(ii) Below a depth of 100 cm, the layer of earth is called soil.
Answer:
False

(iii) All crops grow better in sandy soil.
Answer:
False

(iv) Overgrazing of pasture lands is also responsible for soil erosion.
Answer:
True

(v) Mining can check soil erosion.
Answer:
False

(vi) Water can easily percolate through clayey soils.
Answer:
False

3. Match the Column ‘A’ with Column ‘B’:

Column ‘A’	Column ‘B’
1. Water can easily percolate through	(a) Pollution of soil
2. This soil is best for growing cotton.	(b) Soil erosion
3. Polythene, plastic and use of insecticides cause	(c) Clay
4. Mining, overgrazing and deforestation cause	(d) Black Soil
5. This soil is used in the manufacture of cement	(e) Sandy Soil

Answer:

Column ‘A’	Column ‘B’
1. Water can easily percolate through	(e) Sandy Soil
2. This soil is best for growing cotton.	(d) Black Soil
3. Polythene, plastic and use of insecticides cause	(a) Pollution of soil
4. Mining, overgrazing and deforestation cause	(b) Soil erosion
5. This soil is used in the manufacture of cement	(c) Clay

4. Choose the Correct Answer:

Question (i)
Which of these does not cause soil erosion ?
(a) Deforestation
(b) Building of check dams
(c) Grazing cattle
(d) Mining.
Answer:
(b) Building of check dams.

Question(ii)
Soil is polluted by:
(a) Rotation of crops
(b) Use of manure
(c) Use of insecticides and chemical fertilizers
(d) Using green manure.
Answer:
(b) Use of manure.

Question (iii)
Soil is not used for:
(a) Making insecticides
(b) Making check dams
(c) Making cement
(d) Making earthen pots
Answer:
(c) Making cement.

Question (iv)
Which of the following can check soil erosion ?
(a) Deforestation
(b) Afforestation
(c) Grazing of cattle
d) Mining.
Answer:
(c) Grazing of cattle.

Question (v)
Soil is used for.
(a) Making cement
(b) Growing crops
(c) Making Dams
(d) All of these.
Answer:
(c) Making Dams.

Very Short Answer Type Questions:

Question (i)
What is humus ?
Answer:
Humus. The dead and rotten leaves of plants or plants, insects or dead animals buried in the soil, animal dung, etc. combine to form organic matter of the soil called Humus.

Question (ii)
Name the organic constituents of soil.
Answer
Organic constituents of soil.

1. Dead and decaying leaves of plants
2. Bodies of dead animals
3. Animal dung etc.

Question (iii)
Name the inorganic constituents of soil.
Answer
Inorganic components of Soil.

1. sand,
2. gravel,
3. clay and
4. mineral.

Question (iv)
What do you mean by loamy soil ?
Answer
Loamy soils. Soil whose particle size is between the size of sandy soil and clayey soil. This soil is best for crops.

Question (v)
Define soil erosion.
Answer:
Soil Erosion. Loss of topsoil due to strong winds, heavy rains, floods or other factors is called Soil erosion.

6. Short Answer Type Questions:

Question (i)
What is Soil Profile ?
Answer:
Soil Profile. A horizontal (or flat) Section passing through different layers of soil is called cut soil profile. The soil layout layers are as follows :

1. organic layer,
2. top soil,
3. bottom soil. Soil,
4. rock fragments,
5. rocky solid floor.

Question (ii)
Draw a labelled diagram of a Soil Profile.
Answer:

Layers of Soil Profile:

1. Mulch (organic layer)
2. Top soil
3. Sub soil
4. Rock Fragments
5. Bed rock

Question (iii)
How does sod get polluted ?
Answer:
Soil Pollution.
Soil pollution occurs due to the presence of unwanted and harmful substances in the soil. The soil is polluted by the following human activities:

1. Increased use of pesticides and chemical fertilizers. We use more pesticides and chemical fertilizers for higher crop yields. All these pesticides and chemical fertilizers remain in the soil due to their non-biodegradable nature which leads to soil contamination.

2. Waste of Industry. Many factories dumps their factory toxic waste in the surrounding areas, which results in soil pollution.

3. Polythene and plastic waste. Many chemicals are used in the manufacture of plastics and polythene. All plastics and polythene are non-biodegradable. When we throw plastic or polythene waste here and there then they remain lying in the soil due to which the soil becomes polluted.

Question (iv)
Why should we plant more bamboo plants ?
Answer:
Cattles need to be grazed in north-hilly and semi-mountainous areas. Grass is repeatedly eaten by cattle as a result of which the top layer of soil becomes bare and loose. As a result, the soil erodes quickly. Bamboo plants are very helpful in controlling soil erosion. So to prevent soil erosion plant as many plants as possible.

Question (v)
List the differences between clayey soil and sandy soil.
Answer:
Differences between clayey soil and sandy soil :

Clayey Soil	Sandy Soil
(1) Particles of clayey soil are less than 0.005 mm in size.	(1) Sand particles size vary from 0.05mm to 2mm.
(2) It contains humus.	(2) It doesn’t contain humus.
(3) There is no empty space in its particles.	(3) It has space in between its particles
(4) Doesn’t allow water to percolate.	(4) It allows water to percolate through.
(5) It is used to make toys, utensils and sculptures	(5) It is not used to make toys and utensils.
(6) It is sticky.	(6) It is not sticky.

Question (vi)
What is a Check Dam ? Why is it built ?
Answer:
Check Dam.
Temporary or small dams are built on drains and canals in mountainous areas so that high speed water can be slowed down and used for irrigation. Doing so can help prevent soil erosion and maintain the fertility of the land. Apart from this, water is collected for irrigation for non-rainy days by stopping water during monsoon.

7. Long Answer Type Questions:

Question (i)
Explain how is soil formed ?
Answer:
Formation of Soil.
Many years ago the earth was hard and rocky. With the passage of time, the rocks were broken into small particles by earthquakes. Rain and river water turned these small particles into more fine particles and carried them away with them. This is how soil was formed.

Question (ii)
Explain the various factors responsible for soil erosion.
Answer:
Factors responsible for soil erosion:

• Floods. Floods wash away the fertile topsoil. Sometimes the crops are washed away with flood water.
• Wind and Storms. Very strong winds and storms blow away the topsoil and cause soil erosion.
• Deforestation. When wild trees are failed down or the trees are uprooted, the soil becomes soft and loose and is easily washed away.
• Over grazing. When animals repeatedly graze a grass field, the top layer of soil becomes bare and loose and is easily eroded.
• Mining. Mining sand, gravel, or minerals become major fector for soil erosion.

Question (iii)
How is soil erosion checked ? Explain.
Answer:
The following steps are taken to check soil erosion:
(i) Planting of trees. Maximum number of local trees should be planted on barren hills and on flat lands grass should be grown. Bamboo plants are very, helpful in preventing erosion of the soil. Therefore, bamboo trees should be planted in hilly and semi-hilly areas.

(ii) Controlling the excavation of mines. Mining should be controlled. The digging should be done in such a way that the mining areas do not become pfond to landslides and soil erosion.

(iii) Grazing alternately. Animals should not be grazed continuously in the same area. After a while, the grazed place should be left empty and undisturbed and the animals should be grazed elsewhere.

(iv) Constructing check dams. Check dams should be constructed on small streams and drains in hilly areas. This will help to reduce soil erosion.

Question (iv)
Classify the soil on the basis of size of particles.
Answer:
Soil classification. Depending on the size of the particles, soil classified as sandy, rocky or loamy.

• Clay. It is a soil whose particles are very fine, like dust and can also pass through muslin cloth. When water is added, it turns into mud and hardens on drying. Such clay is used to make pottery and utensils.
• Sandy Soil. It’s particles are larger than clay particles. These particles cannot pass through the muslin cloth. Desert soils are usually sandy. Water is not retained in this type of soil.
• Rocky Soils. Such soil particles are very large and can be picked by hand. Such particles cannot even pass through a filter.
• Loamy Soil. The size of loamy soil particles is between the size of sand and clay particles. This type of soil is best for crops.

PSEB Solutions for Class 7 Science Soil Important Questions and Answers

1. Fill in the Blanks:

(i) The …………………. layer of earth in which crops can be grown is called soil.
Answer:
upper most

(ii) Particle size of ………………. soil lie between particle size of sand and clay.
Answer:
loam

(iii) The pH of ………………. soil lie between 8 to 14.
Answer:
Alkaline

(iv) Loss of top layer of soil is called ………………..
Answer:
soil erosion

(v) Inclusion of unwanted and harmful substances in the soil is called …………………
Answer:
soil pollution

2. Match the Column ‘I’ with Column ‘II’:

Column ‘I’	Column ‘II’
(i) A home for living organisms	(a) Large particles
(ii) Upper layer of soil	(b) All kinds of soil
(iii) Sandy soil	(c) Dark in colour
(iv) Middle layer of the soil	(d) Small particles and packed closely.
(v) Clayey soil	(e) Lesser amount of humus

Answer:

Column ‘I’	Column ‘II’
(i) A home for living organisms	(b) All kinds of soil.
(ii) Upper layer of soil	(c) Dark in colour.
(iii) Sandy soil	(a) Large particles.
(iv) Middle layer of the soil	(e) lesser amount of humus
(v) Clayey soil	(d) Small particles and packed closely.

3. Choose the Correct Answer:

Question (i)
The removal of top layer of soil by water and wind is called ……………………. .
(a) Soil pollution
(b) Soil erosion
(c) Soil profile
(d) Weathering.
Answer:
(b) Soil erosion.

Question (ii)
Which soil is the best for agriculture ?
(a) Loamy
(b) Sandy
(c) Clayey
(d) Sandy & Loamy.
Answer:
(a) Loamy.

Question (iii)
Which soil is better for pulse s ?
(a) Clayey
(b) Sandy
(c) Sandy and Loamy
(d) Loamy.
Answer:
(d) Loamy.

Question (iv)
Which layer of the soil is rich in minerals ?
(a) A-Horizon
(b) B-Horizon
(c) C-Horizon
(d) None of the above.
Answer:
(b) B-Horizon.

Question (v)
Which soil is well aerated ?
(a) Clayey
(b) Loamy
(c) Sandy and Loamy
(d) Sandy.
Answer:
(d) Sandy.

Question (vi)
The uppermost laver of earth’s crust is called
(a) Soil
(b) Wind
(c) Water
(d) None of the above.
Answer:
(a) Soil.

State True or False:

(i) Chemical fertilizers pollute the soil.
Answer:
True

(ii) From surface 30-40 cm deep layer of Earth in which plants can grow is called soil.
Answer:
True

(iii) The soil which contains iron salts is good for growing cotton.
Answer:
True

(iv) It only takes a few months for the top layer of soil to form.
Answer:
False

Very Short Answer Type Questions

Question 1.
What is soil ?
Answer:
Soil. The uppermost layer of earth’s crust is soil.

Question 2.
Are all the particles of soil of same size ?
Answer:
No, all the particles of soil are not of same size even the shape and colour of different soils is different.

Question 3.
On which factors, soil layers can be differentiated ?
Answer:
Soil colour, texture, depth and chemical composition.

Question 4.
Name the organisms found is soil.
Answer:
Worms, rodents, moles, beetles.

Question 5.
What is nature of bed rock ?
Answer:
Bed rock is hard in nature.

Question 6.
Which soil is well aerated ?
Answer:
Sandy soil.

Question 7.
Which soil is good for rice ?
Answer:
Clayey soil.

Question 8.
Which soil can retain more water ?
Answer:
Top soil.

Question 9.
Which type of soil is good for pulses ?
Answer:
Loamy soil.

Short Answer Type Qucstions

Question 1.
Explain the soil as a medium for growth of plants.
Answer:
Plants need soil to grow in as roots of plant take water and minerals from the soil. Soil also holds firmly the roots of plants, thus giving them support.

Question 2.
How can you call soil as a natural resource ?
Answer:
Soil as a natural resource. Soil is one of the most important natural land resource. Greenary on earth is possible only due to soil. Plants need soil to grow, for support and for nutrients.

Soil is main vital support to the living world. It provides the basic building material for shelter, bricks and mortar. Soil is also source of many elements such as aluminium, potassium etc. It also acts as good habitat for many organisms.

Question 3.
How is clayey soil useful for crops?
Answer:
Clayey soil has more power of retaining water. Clayey soil is rich in humus and is, therefore, very fertile. So it is good for crops.

Question 4.
Explain how soil pollution and soil erosion could be prevented.
Answer:
Prevention of Soil pollution:

1. Ban on plastic and polythene bags.
2. Treatment of waste before dumping it in the soil.

Prevention of soil erosion:

1. Growing trees (cultivation)
2. Crop rotation.
3. Embankment of rivers.
4. Afforestation.

Long Answer Type Question

Question 1.
Write uses of soil.
Answer:
Soil is the topmost layer of the earth’s crust. It is formed due to the breaking down of rocks by the action of heat from the sun, wind, and water.
Different uses of soil are:

• Soil is one of the most important natural resources.
• Soil supports the growth of plants by holding the roots firmly and supplying water and nutrients.
• Soil is the home of many organisms.
• Soil is essential for agriculture. Agriculture provides food, clothing, and shelter for all.
• Soil is thus an inseparable part of our life.