NCERT Solutions for Class 7 Science Chapter 9 Soil
Written by Team Trustudies
Updated at 2021-05-07
NCERT solutions for class 7 Science Chapter 9 Soil Exercise
Tick the most suitable answer in question 1 and 2.
Q.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
NCERT Solutions for Class 7 Science Chapter 9 Soil
Answer :
(iii) Minerals, organic matter, air and water
Q.3 Match the items in Column I with those in Column II:
Column I
(i) A home for living organisms
(ii) Upper layer of the soil
(iii) Sandy soil
(iv) Middle layer of the soil
(v) Clayey soil
Column II
(a) Large particles
(b) All kinds of soil
(c) Dark in colour
(d) Small particles and packed tight
(e) Lesser amount of humus
NCERT Solutions for Class 7 Science Chapter 9 Soil
Answer :
Column I \(\rightarrow \) Column II
(i) A home for living organisms \(\rightarrow \) (b) All kinds of soil
(ii) Upper layer of the soil \(\rightarrow \) (c) Dark in colour
(iii) Sandy soil \(\rightarrow \) (a) Large particles
(iv) Middle layer of the soil\(\rightarrow \) (e) Lesser amount of humus
(v) Clayey soil\(\rightarrow \) (d) Small particles and packed tight
NCERT Solutions for Class 7 Science Chapter 9 Soil
Answer :
(1) The outer layer or the uppermost layer of the earth is formed of soil. The soil is a mixture that contains minerals, organic matter, and living organisms all of which interact slowly yet constantly.
(2) Soil is formed through the process of weathering. Weathering is a process of physical breakdown and chemical decomposition of rocks and minerals near or at the surface of the earth. .
(3) Rock is broken down into small particles. These small particles mix with humus (organic matter) and form soil.
(4) This physical and chemical decomposition is primarily done by wind, water, and climate. As a result of these processes, large rock pieces are converted into smaller pieces and eventually to the soil.
NCERT Solutions for Class 7 Science Chapter 9 Soil
Answer :
Clayey soil is useful for crops for the following reasons:
(1) Due to the very small size of the particles of clayey soil, particles are packed tightly and therefore can retain water.
(2) Clayey soil is also rich in organic matter. Clayey soil is rich in humus and is very fertile. For growing crops such as wheat, gram, and paddy, the soil that is good at retaining water and rich in organic matter is suitable.
Therefore, clayey soils having these characteristics are useful for such kinds of crops.
NCERT Solutions for Class 7 Science Chapter 9 Soil
Answer :
Clayey soil :
(i) Particles are tightly packed.
(ii) It has much smaller particles.
(iii) Very little air is trapped between the particles
(iv) Rich in humus and organic substance.
(v) Good for growing various crops.
Sandy soil :
(I) Particles are loosely packed.
(ii) It has larger particles than clayey soil.
(iii) More air is trapped between the particles.
(iv) Not rich in humus and organic nutrients.
(v) Not suitable for growing crops.
Q.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.
NCERT Solutions for Class 7 Science Chapter 9 Soil
Answer :
Amount of water = 200 ml
Percolation time = 40 minutes
\(\therefore \) Percolation rate =\(\frac{amount of water}{percolation time} \)
= \(\frac{200ml}{40min} \) = 5 ml/min
Therefore, rate of percolation is 5 ml/min
NCERT Solutions for Class 7 Science Chapter 9 Soil
Answer :
Prevention of soil pollution :
(i) Recycling of non-biodegradable wastes. Plastics and polythene bags should be disposed of properly.
(ii) Limiting the use of pesticides and insecticides.
(iii) Making dumping grounds of non-biodegradable wastes far away from fertile land.
(iv) Some waste products from industries and homes pollute the soil.
These pollutants should be treated chemically to make them harmless before they are disposed of.
Prevention of soil erosion:
(i) Planting more and more trees will result in the reduction of soil erosion.
(ii) By stopping deforestation and avoiding overgrazing of animals.
(iii) Reduce cutting down of trees or deforestation.
(iv) Using step farming in hilly regions.
(v) Mulch matting can be used to reduce erosion on the slopes.
(vi) Putting a series of fiber logs to prevent any water or soil from washing away.
Q.10 Solve the following crossword puzzle with the clues given:
Across
2. Plantation prevents it.5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.
Down
1. In desert soil erosion occurs through.3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.
NCERT Solutions for Class 7 Science Chapter 9 Soil
Answer :
Across:
2. Erosion
5. Polythene
6. Clay
7. Earthworm
Down:
1. Wind
3. Wheat
4. Sandy
5. Profile
