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

Which of the following 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 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) $C{O}_2$ and CO

(3) $S{O}_3$ and CO

(4) $S{O}_2$ and $N{O}_2$

B.O.D is connected with-

1. Organic matter

2. Microbes

3. Both (1) and (2) 

4. None of the above.

$S{O}_2$ pollution is indicated by

(1) Grasses

(2) Mosses

(3) Lichens

(4) Fossils

The most hazardous metal pollutant of automobile exhaust is : 

1. Hg

2. Cd

3. Pb

4. Cu

The common nitrogen-fixer in paddy fields is
1. Azospirillum

2. Oscillatoria

3. Frankia

4. Rhizobium

Ozone layer of upper atmosphere is being destroyed by

(1) Sulphur dioxide

(2) Carbon dioxide

(3) Chlorofluorocarbon

(4) Smog