Acid rain occurs due to the presence of : 

1. $S{O}_2$ in the atmosphere

2. $N{H}_3$  in the atmosphere

3. $C{O}_2$  in the atmosphere

4. $N_{2}O$  in the atmosphere

An increase in ${\mathrm{CO}}_2$ concentration in the atmosphere will result in : 

1. Adverse effects on natural vegetation.

2. Global warming.

3. Temperature decrease in a global atmosphere.

4. Genetic disorders in plants and animals.

The most harmful air pollutant produced by automobiles is- 

1. ${\mathrm{HNO}}_2$

2. NO

3. ${\mathrm{SO}}_2$

4. CO

The most hazardous metal pollutant of automobile exhaust is : 

1. Hg

2. Cd

3. Pb

4. Cu

B.O.D is connected with-

1. Organic matter

2. Microbes

3. Both (1) and (2) 

4. None of the above.

The major contributor to water pollution among the following is- 

1. Sound

2. ${\mathrm{SO}}_2$

3. Salts of arsenic

4. Sewage

The main factor of water pollution is:

1. Smoke

2. Industrial waste

3. Detergent

4. Ammonia

Ozone depletion occurs in : 

1. Tropospheric pollution.

2. Stratospheric  pollution.

3. Air pollution.

4. Photochemical smog.

Major component of acid rain is : 

1. ${\mathrm{HNO}}_3$ 

2. ${\mathrm{H}}_2{\mathrm{SO}}_4$

3. HCl

4. ${\mathrm{H}}_2{\mathrm{CO}}_3$

... is not a greenhouse gas :-
1. Hydrogen
2. Carbon dioxide
3. Methane
4. Nitrous oxide or $N_{2}O$