Question

Question 21
Fill in the blanks with the help of words given in bracket after each sentence.
(a) When air is contaminated by___ substances which have a ___ effect on both the ___ and ___, it is referred to as ___. (air pollution, harmful, living, unwanted, non-living, pollutants).
(b) Many ___ are responsible for causing ___ pollution. Petroleum ___ are a major source of ___ pollutants like ___ and ___. (sulphur dioxide, refineries, industries, nitrogen dioxide, gaseous, liquid, people, air).
(c) While ___ your teeth, leaving the ___ running may waste several ___ of water. (tap, litres, brushing, washing, drops)
(d) Water which is suitable for ___ is called ___ water. (washing, bathing, drinking, potable, soft).
(e) Water which looks clean still has disease carrying ___and ___ impurities. (insects, microorganism, particles, dissolved, harmful).

Answer 1

(a)When air is contaminated by unwanted substances which have a harmful effect on both be living and non-living, it is referred to as air pollution.
(b)Many Industries are responsible for causing air pollution. Petroleum refineries are a major source of gaseous pollutants like sulphur dioxide and nitrogen dioxide.
(c)While brushing your teeth, leaving the tap running may waste several litres of water.
(d)Water which is suitable for drinking is called potable water.
(e)Water which looks clean still has disease-carrying microorganisms and dissolved impurities.