NCERT Solutions Class 7 Science Chapter 9 Soil

NCERT Solutions for Class 7 Science for chapter 9 Soil

Tick the most suitable answer in questions 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

Ans.1 In addition to the rock particles, the soil contains

(iii) minerals, organic matter, air and water

Q.2 The water holding capacity is the highest in

(i) sandy soil
(ii) clayey soil
(iii) loamy soil
(iv) mixture of sand and loam

Ans.2 The water holding capacity is the highest in (ii) clayey soil

Q.3 Match the items in Column I with those in Column II:

Ans.3 The correctly matched contents of Column I and Column II are as follows:

Q.4 Explain how soil is formed.

Ans.4 Soil is formed by the process of weathering. In this process, rocks are broken into smaller particles by the action of wind, water and various other climatic factors. The slow and continuous action of these factors converts massive rocks into fine particles of soil over a period of millions of years.

Q.5 How is clayey soil useful for crops?

Ans.5 Clayey soil has maximum water holding capacity due to which it retains water for absorption by the plants for longer period of time. Also, clayey soil is rich in humus that provides nutrients to the plants for their growth. Thus, clayey soil is very useful for the crops.

Q.6 List the differences between clayey soil and sandy soil.

Ans.6 The differences between clayey soil and sandy soil are as follows:

Q.7 Sketch the cross section of soil and label the various layers.

Ans.7 Following is the well-labelled sketch of the cross- section of soil and its various layers:

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.

Ans.8 The percolation rate is given by the following expression:

Percolation rate = amount of water (mL)/time taken(min)
Therefore, Percolation rate = 200 mL/40min = 5 mL/min

Q.9 Explain how soil pollution and soil erosion could be prevented.

Ans.9

Ways of preventing soil pollution are as follows:

1. Minimising the use of pesticides and fertilisers
2. Banning the use of polythene
3. Chemicals and other waste products of industries should be treated before releasing them into soil or water
4. Abandoning the practice of defecation in open

Ways of preventing soil erosion are as follows:

1. Planting of trees at large scale
2. Putting check on deforestation
3. Protecting and expanding forest covers

Q.10 Solve the following crossword puzzle with the clues given: