NCERT Solutions for Class 7 Science Chapter 9 Soil
Exercises
Tick the most suitable answer in questions 1 and 2.
Question:- 1. In addition to the rock particles, the soil contains
(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants
Answer:- (iii) minerals, organic matter, air and water
Question:- 2. The water holding capacity is the highest in
(i) sandy soil
(ii) clayey soil
(iii) loamy soil
(iv) mixture of sand and loam
Answer:- (ii) clayey soil
Question:- 3. Match the items in Column I with those in Column II:
Column I | Column II |
(i) A home for living organisms | (a) Large particles |
(ii) Upper layer of the soil | (b) All kinds of soil |
(iii) Sandy soil | (c) Dark in colour |
(iv) Middle layer of the soil | (d) Small particles and packed tight |
(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 the 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 tight |
Question:- 4. Explain how soil is formed.
Answer:- The process by which soil is created is called weathering. It is the physical deterioration and chemical degradation of rocks and minerals near or on the earth’s surface. Wind, water, and climate are the primary causes of physical and chemical disintegration. Large rock fragments are reduced to smaller fragments and finally to soil as a result of these processes.
Question:- 5. How is clayey soil useful for crops?
Answer:- Clayey soil is beneficial to crops for a variety of reasons.
- It has a large capacity to hold water.
- Organic stuff is abundant in clayey soil.
- Cereals such as wheat grow well in clayey and loamy soils.
- Clayey soil’s water-holding capability helps the growth of crops such as paddy, which require more water to grow.
Question:- 6. List the differences between clayey soil and sandy soil.
Answer:-
Clayey Soil | Sandy Soil |
1. Particles are finer | 1. Particles are larger |
2 Particles are tightly packed | 2. Particles are loosely packed |
3. Holds a good amount of water | 3.Water holding capacity is low |
4. It is heavy in weight | 4. It is light in weight |
5. Rich in humus and organic nutrients | 5. Not rich in humus and organic nutrients |
6. Very little air is trapped between the particles | 6. More air is trapped between the particles |
Question:- 7. Sketch the cross section of soil and label the various layers.
Answer:-
Question:- 8. Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
Answer:-
Question:- 9. Explain how soil pollution and soil erosion could be prevented.
Answer:- The following measures can be used to reduce soil pollution:
- We can prevent soil pollution by lowering our use of plastics.
- We can reduce soil pollution by limiting the use of chemical fertilisers and pesticides.
The following steps can be taken to reduce soil erosion.
- Soil erosion will be reduced by increasing the number of trees planted.
- By halting deforestation and avoiding animal overgrazing.
Question:- 10. Solve the following crossword puzzle with the clues given:
Across
- Plantation prevents it.
- Use should be banned to avoid soil pollution.
- Type of soil used for making pottery.
- Living organism in the soil.
Down
- In desert soil erosion occurs through.
- Clay and loam are suitable for cereals like.
- This type of soil can hold very little water.
- Collective name for layers of soil.
Answer:-
Across:
- Erosion
- Polythene
- Clay
- Earthworm
Down:
- Wind
- Wheat
- Sandy
- Profile
