Chhattisgarh State Board Class 7 Science Chapter 19 Soil Exercise Multiple Choice, Questions and Answers here.
Answer these
(1) What is known as soil erosion?
Answer:- The roots of the plants hold fast the soil. Most of the nutrients in the soil is in its upper layer. Due to which the soil becomes fertile. Strong wind and rains wash away or erode this fertile layers. Loss or destruction of this upper fertile layer is known as soil erosion.
(2) Write three causes of soil pollution?
Answer:- Causes of soil pollution:-
(1) things which are made of metals, glass piece, polythene bags, and things, made of plastic as buckets, bottles, boxes etc are also there. Decomposition of these things by the micro-organisms is very slow or even negligible. This is a causes of pollution and waste products make the soil pollution.
(2) Waste product from the factories can also polluted the soil.
(3) Agriculture is the basis of life, excessive spraying of the germicides and fungicides on the crops is a cause of soil pollution.
(3) How will you preserve soil of your neighborhood?
Answer:- (1) The formation of soil is not possible. Its formation is by nature. Therefore it must be used carefully, so that the soil is not destroy.
(2) By stopping unnecessary cutting of trees in neighboring forest.
(3) All carbonic waste (cow dung, leaves, left over of crops etc) must be returned to the soil as biological manure.
(4) By using pits dug for the extraction of mineral must be filled.
(4) What is the effect of the cutting of trees, on soil?
Answer:- The effect of the cutting of trees, on soil is –
(1) Cutting of trees causes soil erosion
(2) Cutting of trees increase deforestation
(3) Due to soil erosion, there are losses other than destruction of the fertile layer
(4) Erosion of soil can also lesson the absorption of water by the ground which increase the dangers of droughts.
Question for practice
(1) Fill in the blanks:-
(1) The biggest particles of the soil is ——.
Answer:- Sandy soil.
(2) —— soil has the maximum property of water retention.
Answer:- Clayey and loamy.
(3) Breaking up of rocks into small particle is called. ——-.
Answer:- Weathering of rocks.
(4) Loss of the upper fertile layer of the soil is called ——–.
Answer:- Soil erosion.
(5) ——- soil is good for growing cotton.
Answer:- Sandy loam.
(2) Write true and false for the statements give below and also correct the false statements.
(1) The soil with humus is not fertile.
Answer:- False. The soil with humus is fertile.
(2) Loamy soil has gravel and clay particles in it.
Answer:- True.
(3) All types of soil have same property of water retention.
Answer:- False, all type of soil have different property of water retention.
(4) Soil must be porous for a good crop.
Answer:- True.
(5) Plant and trees increase soil erosion.
Answer:- False. Plant and trees decrease soil erosion.
(3) Answer the following question.
(1) How can you prove that soil has micro organisms in it?
Answer:- (1) Soil has micro-organisms as bacteria fungus, insect, earthworms etc.
(2) Micro-organisms in the soil release carbon-dioxide through respiration.
(3) By testing two sample of soil in a laboratory.
(2) How can you stop soil from being polluted.
Answer:- Soil pollution can be stopped by
(1) By using easily biodegradable things which do not effect soil.
(2) Waste from the factories dispose properly to avoid soil pollution.
(3) Stop using polythene bag, bottles, it is hard to decomposite it.
(4) How will you test the capability of water retention in red sandy soil, red loamy soil and black soil found in Chhattisgarh.
Answer:- The capability of water retention:-
Material required:- 3 funnels, 3 measuring cylinder, glasses, slimy soil, sandy soil and loamy soil, filter paper and cotton.
Procedure:- (i) Place the filter paper in the funnel and put cotton on it.
(ii) Put 50 g of each soil in different funnel.
(iii) Pour 50 ml water in each sample of the soil slowly on the upper surface.
(iv) After sometime when the water-drops stop falling in the measuring cylinder, measure the quantity of the water collected in the cylinder.
(v) From these we get the capacity of water retention in red sand soil is very less. Slimy soil have high capacity of water retention.
(5) What will happen if soil disappear from the earth?
Answer:- (1) Soil is also a basis of life as air and water.
(2) Plant and animals use air and water present in the pores of the soil.
(3) If soil disappear there is no fields, and no cultivation of crops and plant.
(4) So, no one can survive on the earth.
(6) Which type of soil is suitable for rice crops
Answer:- (1) Clayey and loamy soils are both suitable for growing rice crop.
(2) Because such soil are good at retaining water.
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