Photochemical smog consists of an excessive amount of $X$ in addition to aldehydes,ketones,$PAN$,etc. $X$ is:

The incorrect statement$(s)$ among $(a) - (d)$ regarding acid rain is (are) :
$(a)$ It can corrode water pipes.
$(b)$ It can damage structures made up of stone.
$(c)$ It cannot cause respiratory ailments in animals.
$(d)$ It is not harmful for trees.

The photochemical smog does not generally contain.

An excess of ......... $ppm$ of $F^-$ ions in drinking water is responsible for a disease known as fluorosis.

Which of the following is not an air pollutant?

Which of the following statements is $NOT$ correct regarding tannins?