These elements are continuously utilized by living beings. But these elements undergo a cyclic process which ensures that they are returned to the atmosphere through various processes. This cyclic process of utilizing various elements and returning them to the atmosphere is called biogeochemical cycle. Due to this, the percentage of oxygen, nitrogen and carbon dioxide remains almost the same in the atmosphere.

The moon does not have atmosphere. Due to this, there is no mechanism to prevent overheating of the surface during daytime; unlike what happens on the earth. Moreover, lack of atmosphere allows all the heat to escape during night. Due to this there are wide variations in temperature on the moon

In coastal areas, sea breeze blows during daytime. The sea breeze has ideal speed for kite flying. Hence, people love to fly kites near the seashore.

Mathura refinery releases toxic gases (like oxides of sulphur) which causes acid rain and hence corrosion of the marbles of Taj Mahal.

It is a bio-indicator and sensitive to SO2 pollution from automobiles. Delhi has maximum number of automobiles, hence has a highly polluted environment.

Marine water is not useful for human and plant life directly. Uneven distribution of limited fresh water resources need conservation to cater to the demands.

 (i) Thermal pollution
(ii) Addition of poisonous (mercury) compounds in water
(iii) Due to blockage of gills with any pollutant. 

Lichens release chemical substances to break the rocks into smaller particles and hence make soil.