The phenomenon in which atmospheric gases trap the heat radiations from the sun near the earth’s surface and keeps it warm is known as-

1. Natural greenhouse effect

2. Tyndall effect

3. Heating effect

4. Joule’s effect

Pollution is a change in physical, chemical or biological characters of our land and water that may be

(1) Desirable and harmful to human

(2) Desirable and useful to a human

(3) Undesirable and harmful to human

(4) undesirable and useful to a human

Major pollutant in Jet plane emission is -

(1) $S{O}_2$

(2) CFC

(3) CO

(4) $CC{l}_4$

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

1. Sulphur dioxide

2. Carbon dioxide

3. Chlorofluorocarbon

4. Smog