Class-7 Subject Science Chapter 9 Soil

 Class-7
Chapter 9 – Soil

Question 1:Tick the most suitable answer in question 1 and 2.

In addition to the rock particles, the soil contains

 (i) air and water

(ii) water and plants

(iii) minerals, organic matter, air and water (  √   )

Question 2:The water holding capacity is the highest in

Answer:The water holding capacity is the highest in

(i) sandy soil

(ii) clayey soil (  √   )

(iii) loamy soil

Question 3:Match the items in Column I with those in Column II:

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: 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. 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 soil.

Question 5:How is clayey soil useful for crops?

Answer:Due to the very small size of the particles of clayey soil, particles are packed tightly and therefore can retain water. Clayey soil is also rich in organic matter. 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 kind of crops.

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

Answer:

Clayey soil		Sandy soil
1.	The proportion of fine particles is higher.	1.	The proportion of large particles is higher.
2.	Particles are packed tightly.	2.	Particles are loosely packed.
3.	It can hold good amount of water.	3.	It’s ability to retain water is low.
4.	Water cannot drain quickly.	4.	Water can drain quickly.
5.	It is heavy in weight.	5.	It is light in weight.

 

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

Answer: