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
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
1. Soil is the topmost layer of the earth’s surface. It consists of rocks and mineral particles, water and air mixed with the soil organic matter. Soil formation begins with the breakdown of rocks called weathering and other materials into smaller pieces on the surface of the earth; and ends with humification and mineralization process.
2. The layers of the soil are called horizons. The uppermost horizon is known as topsoil layer. The topsoil layer is a mixture of sand, slit, clay and broken down organic matter, is called humus. Humus is rich, highly decomposed organic matter mostly made from dead plants, dead insects and twigs; incomplete decomposed black coloured organic matter.
3. Sandy soils contains mainly sand about 70 - 80% of sand, large particles with large spaces. It contains very few amount of humus. It is found in desert or dried areas. Sandy soil has large particles with large spaces between them which dries out quickly that is not good for plants. Its water holding capacity is very low.
4. The middle layer is called subsoil. Subsoil is the layer of soil under the topsoil on the surface of the ground. It contains lower amount of humus.
5. Clayey soil contains mainly clay about > 50% clay having very small particles with very small spaces. Clayey soil also contains very few amount of humus. Clayey soil is heavy because it has ability to hold more water than the sandy soil.
Popular Questions of Class 7 Science
- Q:-
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food - Q:-
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth
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Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
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Sketch the cross section of soil and label the various layers.
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When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
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Write one similarity and one difference between the nutrition in amoeba and human beings.
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Why does an athlete breathe faster and deeper than usual after finishing the race?
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David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be
(i) 3 m (ii) 5 m
(iii) 6 m (iv) 8 m - Q:-
One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be
(a) 80°C (b) more than 50°C but less than 80°C
(c) 20°C (d) between 30°C and 50°C - Q:-
Stainless steel pans are usually provided with copper bottoms. The reason for this could be that
(a) copper bottom makes the pan more durable.
(b) such pans appear colourful.
(c) copper is a better conductor of heat than the stainless steel.
(d) copper is easier to clean than the stainless steel.
Recently Viewed Questions of Class 7 Science
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Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
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Suppose the two photographs, shown in Fig. 13.1 and Fig. 13.2, had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs, calculate the speed of the blue car.
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Which of the statements given below is correct?
(i) In winter the winds flow from the land to the ocean.
(ii) In summer the winds flow from the land towards the ocean.
(iii) A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it.
(iv) The coastline of India is not vulnerable to cyclones. - Q:-
State similarities and differences between the laboratory thermometer and the clinical thermometer.
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Sketch the reproductive parts of a flower.
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Fill in the blanks with the appropriate answers:
(a) People obtain groundwater through________ and ________. (b) Three forms of water are ________, ________ and ________.
(c) The water bearing layer of the earth is ________.
(d) The process of water seepage into the ground is called ________. - Q:-
In Fig. 17.15, the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels:
clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil, roots, water table.
- Q:-
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth - Q:-
Explain how groundwater is recharged?
- Q:-
An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will
(a) flow from iron ball to water.
(b) not flow from iron ball to water or from water to iron ball.
(c) flow from water to iron ball.
(d) increase the temperature of both.
- NCERT Chapter