Which of the following is a gaseous pollutant?

The depletion of ozone in Antarctica is caused by the formation of which of the following substances?

In drinking water,if the maximum prescribed concentration of copper is $x \ mg \ dm^{-3}$,the maximum prescribed concentration of zinc will be

Which region of the atmosphere is the domain of all living organisms?

Arrange the following hydrocarbon fuels in increasing order of their polluting strength: $LPG$,$CNG$,and Kerosene.

Given below are two statements :-
Statement $I :$ The value of the parameter "Biochemical Oxygen Demand $(BOD)$" is important for survival of aquatic life.
Statement $II :$ The optimum value of $BOD$ is $6.5 \ ppm$.
In the light of the above statements,choose the most appropriate answer from the options given below: