Soil, NCERT (CBSE) Class 7 Science | CBSE Guess Sample questions answers

 



CBSE Class 7, NCERT Science Solutions and Guide

Chapter 9, Soil

CBSE Guess - CBSE Guide - Solutions of CBSE Sample Questions


CBSE Sample Questions (1 mark)

Question.1: What are the important constituents of soil?
Solution: Air, water, minerals, and organic matter (humus).
Question.2: Define:
(a)    Soil profile
(b)    Humus
(c)    Soil
Solution:
(a)    Soil Profile: See answer of Q.No.3 of Long Questions below.
(b)    The rotting dead matter is called humus.
(c)    The mixture of rock particles and humus make soil. It is the outer most layer of the earth’s crust.
Question.3: Give one feature of well aerated soil.
Solution: Sufficient space for air movement.
Question.4: What are the factors that influence soil formation?
Solution: See the answer of the Q.No.4 of NCERT Textbook Exercise above.

CBSE Sample Questions (3 – 4 marks)

Question.5: What are the organic and inorganic components of soil?
Solution: The inorganic components of soil comprise minerals which are derived from fragmentation and weathering of rocks.  The pore spaces between the mineral particles of soil are occupied by water and gases.
The organic components of soil comprise organic wastes, dead animals, plants and products formed by their decomposition 
Question.6: List out the various types of vegetation grown on different types of soil.
Solution: The various types of vegetation grown on different types of soils are listed below:
(i)    Clayey and loamy soils are suitable for growing cereals like wheat, gram etc. These types of soils are good at retraining water.
(ii)    For paddy, soils rich in clay and organic matter and having a good capacity to retain water are ideal.
(iii)    For lentils and other pulses, loamy soil is better since they can drain water easily.
(iv)    For cotton, sandy loam or loam which drain water easily and can hold good amount of air are more suitable.
Question.7: What is soil profile? Discuss the layers found in the soil profile.
Solution: Soil formation over a period of time results in vertical stratification of horizontal layers one over the other. Such a vertical section of soil comprising different layers starting from the top mature soil to underlying bed-rock is called a soil profile. Each layer differs from another in texture, colour, depth and chemical composition. These layers are called ‘horizons’. There are three horizons in the soil profile as described below:
(a)   A-horizon - This is the uppermost layer or top soil. It is generally dark in colour because of its rich humus contents. The large content of humus makes it more fertile and provides nutrients to growing plants. This layer is generally soft, porous and has the highest water holding capacity. It provides shelter to many living organisms such as, worms, rodents, moles and beetles.
(b)   B-horizon - This is the middle layer and has lesser amount of humus but more of iron oxide and minerals. This layer is little harder and more compact due to formation of aggregation of iron and aluminium compounds.
(c)   C-horizon - This layer is made up of small lumps of rocks which have cracks and crevices. This horizon thus, represents weathered parent material which has not become true soil. 
(d)   Bedrock - It is hard and difficult to dig with a spade.

Objective type CBSE Questions (1 mark questions)

Question.8: Fill in the blanks:
(a)         Soil is formed by ______ of rocks.
(b)         A dark soil is usually rich in ______.
(c)         Soil erosion can be stopped by ____.
(d)         ______ soil is used to make pots, toys and statues.
(e)         _______ portion of soil contains air.
(f)         Percolation rate of water is highest in _____ soil and least in ____ soil.
(g)   The proportion of sand, silt and clay in a soil sample determines ______ of soil.
(h)         Particle size of sandy soil range between ______.
(i)         Particle size greater than 2.0 mm is known as ______.
(j)         Deep ploughing and over grazing can cause ______.
Solution: (a) weathering (b) humus (c) plantation (d) clayey (e) upper (f) clayey, sandy (g) texture (h) 0.05-2.0 mm (i) gravel (j) soil erosion.
Answer: Ghana.

 Further study ­(NCERT answers)     
For Answers of NCERT (CBSE) Science Textbook Exercise Questions of this Chapter ‘SOIL’ and also other Class and Subject wise chapters visit:

 

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