Soil | Science | Chapter 9 | Class 7th | Questions and Answers |

JANDKNCERT | Science | Class 7th |

Soil | Science | Chapter 9 | Class 7th | Questions, and Answers |

 

Chapter 9: Soil

EXERCISE

 

Tick the most suitable answer in questions 1 to 5.

Q1. 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. (iii) Minerals, organic matter, air, and water

 

Q2. The water holding capacity is the highest in

(i) Sandy soil

(ii) Clayey soil

(iii) Loamy soil

(iv) A mixture of sand and loam

Ans. (ii) Clayey soil

 

Q3. The process of soil formation is called

(i) Conservation

(ii) Weathering

(iii) Erosion

(iv) Pedogenesis

Ans. (ii) Weathering

 

Q4. Soil profile consists of

(i) Two layers

(ii) Three layers

(iii) Four layers

(iv) Five layers

Ans. (iii) Four layers

 

Q5. Humus is present in

(i) A-Horizon

(ii) B-Horizon

(iii) C-Horizon

(iv) Bedrock

Ans. (i) A-Horizon

 

Q6. 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

 

Ans.

 

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

 

Q7. Explain how soil is formed.

Ans. Soil is formed by the process of weathering. Weathering is a process of breakdown of rocks by the action of wind, water, and climate.

 

Q8. How is clayey soil useful for crops?

Ans. Clayey soil is useful for crops because it is rich in humus and has a good holding capacity of water.

 

Q9. List the differences between clayey soil and sandy soil.

Ans.

 

Clayey Soil	Sandy Soil
1. It is rich in organic matter. 2. Its particles are fine and tightly packed. 3. It holds a good amount of water. 4. Less air is trapped between particles.	1. It is not rich in organic matter. 2. Its particles are large and loosely packed. 3. Its water holding capacity is low. 4.More air is trapped between particles.

 

Q10. Sketch the cross-section of soil and label the various layers.

Ans.

 

  

Q11. 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.

Amount of water = 200 mL

Percolation time = 40 min

Percolation rate = Amount of water in mL / Percolation time in minutes

Therefore,

Percolation rate = 200 mL / 40 min

That is, 5 mL/min

 

Also Read: More about your body structure

 

Q12. Explain how soil pollution and soil erosion could be prevented.

Ans. Soil pollution can be prevented by avoiding using plastics and polythene things and by controlling the use of chemical fertilizers and pesticides.

Soil erosion can be prevented by stopping the cutting of trees and overgrazing of animals and by planting more trees.

 

Q13. Solve the following crossword puzzle with the clues given:

 

 

1
		2
												3
		4		5
							6
				7

 

 

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 the 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.

 

Ans.

 

W

I

E

R

O

S

I

O

N

N

W

D

H

S

P

O

L

Y

T

H

E

N

E

A

R

A

N

O

T

D

F

C

L

A

Y

Y

I

L

E

A

R

T

H

W

O

R

M