Question 1

Dinitrogen is a robust compound, but reacts at high altitude to form oxides. The oxide of nitrogen that can damage plant leaves and retard photosynthesis is :

Accepted Answer

N _2( ~g )+ O _2( ~g ) 2 NO ( g ) 2 NO ( g )+ O _2( ~g ) 2 NO _2( ~g ) Higher concentration of NO _2 damage the leaves and retard the rate of photosynthesis.

Question 2

Photochemical smog formed in congested metropolitan cities mainly consists of

Accepted Answer

Photochemical smog O _3, PAN , NO _x

Question 3

The photochemical smog does not generally contain:

Accepted Answer

Photochemical smog contains nitrogen dioxide ( NO _2 ), Ozone ( O _3 ), PAN (peroxyacetylnitrate), and compounds containing - CHO group.

Question 4

Biochemical oxygen demand(BOD) value can be a measure of water pollution caused by the organic matter. Which of the following statements is correct?

Accepted Answer

Clean water has BOD value less than 5 ppm . Polluted water has BOD value higher than 10 ppm .

Question 5

The greenhouse effect is because of the

Accepted Answer

Green house gases such as CO _ 2 , ozone, methane, the chlorofluorocarbon compounds and water vapour form a thick cover around the earth which prevents the IR rays emitted by the earth to escape. It gradually leads to increase in temperature of atmosphere.

Environmental Chemistry — Previous Year Questions & Solutions