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:
