Q44 of 50 Page 181

Assertion (A): Excessive use of chlorinated syntheticpesticides causes soil and water pollution.

Reason (R): Such pesticides are non-biodegradable.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv) A is not correct but R is correct.


(i) Both A and R are correct and R is the correct explanation of A.

Explanation: Excessive use of chlorinated synthetic pesticides causes soil and water pollution. This is due to the fact that fertilizers slowly get accumulated in the water bodies and start hindering with others too. This in turn cause several problems as they start migrating from one place to other water bodies with the help of rain. Also, pesticides are chemicals which can not be decomposed or degraded using the microorganisms. Therefore, they are non-biodegradable.


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42

Assertion (A): Carbon dioxide is one of the important greenhouse gases.

Reason (R): It is largely produced by respiratory function of


animals and plants.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv) A is not correct but R is correct


 43

Assertion (A): Ozone is destroyed by solar radiation in upper stratosphere.

Reason (R): Thinning of the ozone layer allows excessive UV radiations to reach the surface of earth.


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv) A is not correct but R is correct


 45

Assertion (A): If BOD level of water in a reservoir islessthan 5 ppm it is highly polluted.

Reason (R): High biological oxygen demand means low activity ofbacteria in water


(i) Both A and R are correct and R is the correct explanation of A.


(ii) Both A and R are correct but R is not the correct explanation of A.


(iii) Both A and R are not correct.


(iv) A is not correct but R is correct.


 46

How can you apply green chemistry for the following:

(i) to control photochemical smog.


(ii) to avoid use of halogenated solvents in drycleaning and that of chlorine in bleaching.


(iii) to reduce use of synthetic detergents.


(iv)to reduce the consumption of petrol and diesel.