9. Soil Science class 7 exercise Additional Questions With Solutions

9. Soil Science class 7 exercise Additional Questions With Solutions ncert book solution in english-medium

NCERT Solutions ⇒ Class 7th

NCERT Books Subjects for class 7th Hindi Medium

9. Soil

topic -1

Chapter Review:

The rotten death material presence in soil is known as humus.
The mixture of rock particles and humus is called the soil.
The breaking down of rocks by the action of wind, water, and climate. This process is called weathering.
A vertical section through different layers of the soil is called the soil profile.
Each layer differ in feel (texture), colour, depth and chemical composition. These layers are referred to as horizons.
The upper layer is generally soft, porous and can retain more water; it is called the topsoil or the A-horizon.
Absorbing water by the soil is known as percolation.
The removal of land surface by water wind or ice is known as soil erosion.
The soil is formed by the breaking down of rocks by the action of wind, water and climate.
The best topsoil for growing plants is loam. Loamy soil is a mixture of sand, clay and another type of soil particle known as silt.
Clayey soil is used to make pots, toys and statues.
Soil is affected by wind, rainfall, temperature, light and humidity.

NCERT Exercise

Exercise NCERT Book

Tick the most suitable answer in questions 1 and 2.

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

Answer:

(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) mixture of sand and loam

Answer:

(ii) Clayey soil.

Q3. 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

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

Q4. Explain how soil is formed.

Answer:

Soil is formed by the breaking down of rocks by the action of wind, water and climate. This process is called weathering and further addition of humus formed by the decomposition of organic matter on the earth's surface make it fertile.

Q5. How is clayey soil useful for crops?

Answer:

Clayey soil retains water to a great extent. Thus the crops which require more water such a soil as, wheat etc. Grow well in clayey soil.

Q6. List the differences between clayey soil and sandy soil.

Answer:

Q7. Sketch the cross section of soil and label the various layers.

Answer:

Q8. 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.

Answer:

Q9. Explain how soil pollution and soil erosion could be prevented.

Answer:

Cutting of trees and deforestayion should be effort should be made to increase the green areas.

Q10. Solve the following crossword puzzle with the clues given:

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 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.

Additional Questions With Solutions

Ques: What is humus?
Ans: The rotten death material presence in soil is known as humus.

Ques: what is weathering?
Ans: The breaking down of rocks by the action of wind, water, and climate. This process is called weathering.

Ques: which are those factors which influence the nature of soil?
Ans:
(i) Rocks from which it has been formed.
(ii) Vegetation that grows in it.

Ques: What is soil profile?
Ans: A vertical section through different layers of the soil is called the soil profile.

Ques: What are Horizons?
Ans: Each layer differ in feel (texture), colour, depth and chemical composition. These l-ayers are referred to as horizons.

Ques: why is the uppermost horizon generally dark in colour?
Ans: As it is rich in humus and minerals.

Ques: Name the layer of the soil which makes the soil fertile.
Ans: Humus.

Ques: What is topsoil?
Ans: The upper layer is generally soft, porous and can retain more water; it is called the topsoil or the A-horizon.

Ques: In how many layers has soil profile been divided?
Ans: Soil profile has been divided in four layers.
(i) topsoil or A-horizon
(ii) B-horizon

C-horizon
Bedrock

Ques: What is called the layer of soil profile which is hard and difficult to dig?
Ans: Bedrock

Ques: What is soil?
Ans: The mixture of rock particles and humus is called the soil.

Ques: What are various classifications of soil?
Ans: The classifications of soil.

Sandy soil.
Clayey soil.
Loamy soil.

Ques: Write three properties of sandy soil.
Ans:

Sandy soils tend to be light.
It is well aerated.
It is rather dry.

Ques: Name the some important climatic factors which affect the soil profile and bring changes in the soil structure.
Ans: Soil is affected by the wind, rainfall, temperature, light and humidity etc.

Ques: What is percolation?
Ans: Absorbing water by the soil is known as percolation.

Ques: What is soil erosion?
Ans: The removal of land surface by water wind or ice is known as soil erosion.

Ques: Explain how soil is formed?
Ans: The soil is formed by the breaking down of rocks by the action of wind, water and climate.

Ques: List the differences between clayey soil and sandy soil.
Ans:

Ques: How is clayey soil useful for crops?
Ans: Clayey soil is useful for crops, because they are rich in humus and are very fertile.