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7 NCERT Science Guide (other chapters)
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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