Which of the following is absent in polluted water

1. Hydrilla

2. Water hyacinth

3. Larva of stone fly

4. Blue green algae

Maximum green house gas released by which country

(1) India

(2) China

(3) U.S.A

(4) Britain

Ozone layer of upper atmosphere is being destroyed by

(1) Sulphur dioxide

(2) Carbon dioxide

(3) Chlorofluorocarbon

(4) Smog

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

2. Oscillatoria

3. Frankia

4. Rhizobium

The most hazardous metal pollutant of automobile exhaust is : 

1. Hg

2. Cd

3. Pb

4. Cu

$S{O}_2$ pollution is indicated by

(1) Grasses

(2) Mosses

(3) Lichens

(4) Fossils

B.O.D is connected with-

1. Organic matter

2. Microbes

3. Both (1) and (2) 

4. None of the above.

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 $N{O}_2$

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

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