Q23 of 32 Page 106

Find out the wrong statements and write them in their correct form.

(1) We can survive for some time without air but we cannot survive even for a few minutes without food.


(2) A brick kiln emits lot of smoke and other harmful gases causing air pollution.


(3) Carbon monoxide is produced by complete burning of fuels such as coal, petrol, diesel.


(4) Chlorination is a commonly used chemical method for killing germs in water.


(5) Water which is suitable for drinking is called soft water.


Statements (b) and (d) are correct statements.


The correct form of statements (a), (c) and (e) are as follows:


(a) We can survive for some time without food but we cannot survive even for a few minutes without air.


(c) Carbon monoxide is produced by incomplete burning of fuels such as coal, petrol, diesel.


(e) Water which is suitable for drinking is called potable water.


More from this chapter

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21

Fill in the blanks with the help of words given in the bracket after each sentence.

(1) When air is contaminated by ________ substances which have a ________ effect on both the ________ and _______, it is referred to as ________.


(2) 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 ).


(3) While ________ your teeth, leaving the ______ running may waste several ______ of water.


(tap, litres, brushing, washing, drops ).


(4) Water which is suitable for _______ is called _______ water.


(washing, bathing, drinking, potable, soft).


(5) Water which looks clean still has disease carrying _______ and _______ impurities.


(insects, micro organism, particles, dissolved, harmful).


 22

Match the items of Column A with those of Column B. Table

 24

In the following statements the underlined words are jumbled up. Write them in their correct form

(1) Air contains 78% ginroten and 21% goncxy.


(2) Vehicle produce high level of pollutants like carbon dioxide, nitrogen oxide, nobrac moondexi and mosek.


(3) Carbon dioxide, thaneme, nitrous oxide and water vapour are known as heengrouse sesga.


(4) Gangotri glacier in Himalaya has started melting because of lablog ringwam.


(5) Whenever harmful substances such as wagese, toxic chemicals, silt, etc. get mixed with water, the water becomes potdulle.


 25

What do CFCs stand for? Name some devices where CFCs are used. Why CFCs are considered as pollutants?