8. Soil
1. Choose the correct option.
a) __________ is/are considered as the best soil for agriculture and gardening. R
i) Loamy soil ii) Sandy soil
iii) Clayey soil iv) Both sandy and clayey soil
ans: Loamy soil
b) B-horizon consists of: R
i) top soil ii) subsoil
iii) parent rock iv) substratum
ans: subsoil
c) Which crop is grown in black soil? An
i) Lentils ii) Gram
iii) Paddy iv) Cotton
ans: Cotton
d) ________ layer does not allow percolation of water. U
i) O-horizon ii) E-horizon
iii) A-horizon iv) R-horizon
ans: R-horizon
2. Give two examples for each of the following. U
a) Crops grown in acidic soil.
ans: potatoes, cabbage, radishes, carrots, cucumbers
(examples may vary, accept all correct answers)
b) Microorganisms that grow on the surface of the rocks.
ans: bacteria, algae, lichens
(examples may vary, accept all correct answers)
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c) Crops grown in alkaline soil.
ans: onions, spinach
(examples may vary, accept all correct answers)
3. In following questions, the Assertion and Reason have been put forward. Read
the statements carefully and choose the correct alternative from the
following: An/E
(A) Both Assertion and Reason are true and the Reason is a correct explanation
of the Assertion.
(B) Both Assertion and Reason are true but the Reason is not a correct
explanation of the Assertion.
(C) Assertion is true but the Reason is false.
(D) Both Assertion and Reason are false.
a) Assertion: Sandy soil is used in construction along with cementing materials.
Reason: Sandy soil does not get sticky and has a light and loose structure.
ans: (A) Both Assertion and Reason are true and the Reason is a correct
explanation of the Assertion.
b) Assertion: A vertical section of the soil from the surface downwards to the
parent rock is known as soil profile.
Reason: There are eight different types of horizons generally found in a soil
profile.
ans: (C) Assertion is true but the Reason is false.
4. Answer the following questions:
a) Explain the term weathering. R
ans: Weathering is the process of weakening and breaking down of rocks by
both living and non-living factors.
b) Why is humus essential for plants? An/E
ans: Humus provides the plants with essential nutrients. It also helps in the
retention of moisture in the soil and loosens the soil allowing better
aeration.
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c) What is meant by the retention capacity of the soil? U
ans: The ability of soil to retain water is known as absorption capacity or
retention capacity of the soil.
d) Differentiate between clayey soil and loamy soil based on the following
criteria: An
(a) Composition
(b) Particle size
ans: Criteria Clayey soil Loamy soil
Composition It contains
about 60% of
clay particles.
It contains a balance of all the three
types of soil particles, i.e. sand, silt
and clay.
Particle size Smallest particle
size
Particle size is smaller than sandy soils
but larger than clayey soils
5. Give reasons for each of the following statements. E
a) We should try to reduce plastic waste as much as possible.
ans: Plastic waste is non-degradable and persists in soil year after year
causing pollution. The productivity of polluted soil reduces over time
and it cannot sustain any life forms thereby becoming useless.
b) Clayey soil is used for pottery and for baking bricks.
ans: Clayey soil is used for pottery and for baking bricks as it naturally forms
lumps with water and can be moulded easily.
6. Maria collected three soil samples (loamy soil, sandy soil and clayey soil) and tested
each of them to see how much water they could hold. The same amounts of soil
and water were added to each funnel and allowed to drain for 5 minutes. Ap, An/E
a) Which soil sample retained the maximum amount of water?
ans: Clayey soil
b) Which soil sample has the maximum amount of space between the soil
particles? Give a reason for your answer.
ans: Sandy soil
It retained the least amount of water as there are huge spaces
between the soil particles.
c) Maria observed that, in 5 minutes, 50 ml of water percolated through loamy
soil. Calculate the rate of percolation of water.
ans: Amount of water = 50 ml
Time taken to percolate = 5 min
The percolation rate =
=
= 10 ml/ min
Set up 1 Set up 2 Set up 3
Loamy soil Sandy soil Clayey soil
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7. Amish visited his village in Meghalaya and observed that people had created steps
on mountain slopes to carry out farming. Ap , U
a) What is this type of farming known as?
ans: Terrace farming
b) State one benefit of this farming practice.
ans: Terrace farming prevents water runoff from the slopes, thus it helps to
reduce soil erosion and conserve soil.
8. Complete the boxes with the help of the clues provided: Ap
a) The type of weathering that involves the breaking down of rocks due to the
action of living organisms.
ans:
b) The gradual transformation of habitable land into deserts.
ans:
9. Higher Order Thinking Skills (HOTS)
Soil X is made of particles with diameters between 0.002 to 0.05 mm while soil Y is
made of particles with diameters more than 2 m. An/E
Which of these soil samples can be silt?
ans: Soil X
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