Methane gas has a global warming potential approximately $25$ times that of which of the following gases?

$A$ water sample has $ppm$ level concentration of following anions: $F^{-} = 10 \ ppm$,$SO_4^{2-} = 100 \ ppm$,$NO_3^{-} = 50 \ ppm$. The anion/anions that make the water sample unsuitable for drinking is/are:

Which of these reactions is not a part of the breakdown of ozone in the stratosphere?

The chlorine free radical reacts with ozone to form a ..... free radical.

Which of the following is a particulate pollutant?

Which among the following is not a greenhouse gas?