Which one of the following is mainly responsible for the depletion of the ozone layer?

Consider the following reactions involving some atmospheric pollutants:
$NO + O_3 \rightarrow NO_2 + O_2$
$NO_2 \xrightarrow{h \nu} NO + O$
$O + O_2 \rightarrow O_3$
$4 NO_2 + O_2 + 2 H_2 O \longrightarrow 4 HNO_3$
$3 CH_4 + 2 O_3 \longrightarrow 3 H_2 C = O + 3 H_2 O$
Based on the above,the formation of formaldehyde from methane in the atmosphere will be controlled by:

Rain water is called as acid rain when its $pH$ is below

The average atmospheric residence time is lowest for which of the given greenhouse gases?

The growth of fish gets inhibited,if the concentration of dissolved oxygen is below $X \ ppm$. The value of $X$ is

Which of the following statements is incorrect?