Soil conservation is the process where

1. Soil is aerated

2. Soil erosion is allowed

3. Soil is protected against loss

4. Sterile soil is converted into fertile soil

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

The concentration of Peroxy Acetyl Nitrate (PAN) maximum in:-

(1) Fog

(2) Smoke

(3) Smog

(4) Photochemical smog

Soil erosion can be prevented by : 

1. Overgrazing

2. Removal of vegetation

3. Afforestation (Plantation)

4. Increasing bird population

Soil erosion is greater when

(1) No rain occurs

(2) Winds do not blow

(3) The rainfall is evenly distributed

(4) The Rainfall is received in heavy down pour

Acid rain is due to an increase in the atmospheric concentration of : 

1. Ozone, and dust

2. $C{O}_{\mathrm{2,}}$ and CO

3. $S{O}_{\mathrm{3,}}$ and CO

4 $S{O}_{\mathrm{2,}}$ and $N{O}_2$

B.O.D is connected with

(1) Organic matter

(2) Microbes

(3) Both

(4) None

$S{O}_2$ pollution is indicated by

1. Grasses

2. Mosses

3. Lichens

4. Fossils

Most hazardous metal pollutant of automobile exhaust is

(1) Hg

(2) Cd

(3) Pb

(4) Cu

The ozone layer of the upper atmosphere is being destroyed by : 

1. Sulphur dioxide

2. Carbon dioxide

3. Chlorofluorocarbon

4. Smog