Answer:
1. Evaporation :- The changing of a liquid to a gas.
2. Automobile :- The major source of pollution.
3. Greenhouse effect :- Carbon dioxide and water vapour trapping heat gives off by Earth.
4. Ozonosphere :- Layer absorbing ultraviolet rays.
5. Condensation :- The changing of gas to a liquid.
6. Ionosphere :- Layer responsible for reflecting radio waves.
7. Troposphere :- The layer in which weather changes.