Planting more and more trees helps to

Which of the following is a major air pollutant?

Methemoglobinemia is due to

Which of the following gases is not a greenhouse gas?

Have you ever observed any water pollution in your area? What measures would you suggest to control it?

Some reactions of $NO_2$ relevant to photochemical smog formation are:
$NO_{2(g)} \xrightarrow{hv} NO_{(g)} + X$
$X + O_2 \rightarrow Y$
$NO + Y \rightarrow NO_2 + A$
$O + O_2 + M \rightarrow B + M$
Identify $A, B, X$ and $Y$.