CBSE Science Class 7 -chapter 9- Soil – NCERT Exercise Solution (Question-Answer) is given below. Total 9 Questions, all are solved here.
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
(i) A home for living organism
(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
(i)A home for living organism
(b)All kinds of soil
(ii)Upper layer of the soil
(c)Dark in colour
(iv)Middle layer of the soil
(e)Lesser amount of humus
(d)Small particles and packed tight
Q4. Explain how soil is formed.
Answer: Soil is formed by the process of weathering of rocks. Weathering is the mechanical and chemical process by which rocks on the Earth’s surface are broken down into smaller piece due to natural forces such as wind, water, frost and roots of plants. Climate regulates soil formation.
Formation of soil is an extremely slow process. It takes 500 years to produce just under an inch of topsoil, which is the most productive layer of soil.
Q5. How is clayey soil useful for crops?
Answer: clayey soil is useful for crops for the following properties:
(i) It retains moisture and becomes wet. It has very good water holding capacity.
(ii) It is rich in Organic matter.
Q6. List the difference between clayey soil and sandy soil.
More than two third of clayey soil is clay.
More than two third of the soil is sand and about one tenth is clayey.
It is made up of small particles for air and water to circulate.
It is made up of large particles for easy circulation of water. It has large spaces.
It retain moisture and becomes wet. When it dries up, it becomes hard and forms deep cracks.
This soil is good for drainage, as it dries up easily and does not retain water.
It is used for making pots.
It is used to grow fruits and vegetables.
Q7. Sketch the cross-section of the soil and label the various layers.
Q8. Razia conducts 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: Given, amount of water = 200 mL
percolation time = 40 min
Percolation rate = amount of water in mL/ percolation time in min
= 200/40 mL/min
= 5 mL/min
Q9. Explain how soil pollution and soil erosion could be prevented.
Answer:Following are the methods that prevent soil pollution:
(i) We should be segregated before throwing and recyclable waste such as plastic and metal should be recycled.
(ii) Harmful chemicals should not be thrown in the soil.
(iii) Biodegradable waste should be converted into compost and used as manure. This will reduce the usage of chemical fertilisers.
Following are some methods that prevent soil erosion:
(i) Planting more and more tree
(ii) Reduce deforestation
(iii) By preventing overgrazing
(iv) By construction of embankments.
NCERT Solutions of Class 7 Science Chapter 9 – Soil — ended 👍👍👍