chemistry

NCERT CLASS 7^TH Q&A SOIL

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:

Question: 4. Explain how soil is formed.

Answer: Soil is formed by the process of weathering. The breaking down of rocks because of the action of wind, rain, ice, etc. is called weathering.

Question: 5. How is clayey soil useful for crops?

Answer: Clayey soil can retain much water and consequently contains lot of moisture even in summer. That’s why it is most useful for crops like paddy which requires lot of water. Clayey soil is useful for wheat also.

Question: 6. List the differences between clayey soil and sandy soil.

Answer:

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:

Given, Time = 40 minute

VolumeVolume of water = 200 ml

Question: 9. Explain how soil pollution and soil erosion could be prevented.

Answer: Soil pollution and soil erosion could be prevented using following:

Plantation

Better farming method, like crop rotation and mixed farming

Use of manure instead of synthetic fertilization.

Use of natural pesticides.

Avoid dumping non-biodegradable items in soil.

Terrace farming in hilly areas.

Question: 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.

Answer: