The depletion of ozone in the stratosphere is caused by .......

Which of the following statements is correct?

Which among the following has the highest concentration of $PAN$?

Rain water is considered as acid rain if its $pH$ is less than.......

If water pollution continues at its present rate,it will eventually

Identify the reactions that occur in photochemical smog.
$(i)$ $CH_2=O + H_2 \longrightarrow CH_3OH$
$(ii)$ $NO_{2(g)} \xrightarrow{h \nu} NO_{(g)} + O_{(g)}$; $O_{(g)} + O_{2(g)} \longrightarrow O_{3(g)}$
$(iii)$ $CH_4 + 2O_3 \longrightarrow CH_2=O + 2H_2O$
$(iv)$ $NO_{(g)} + O_{3(g)} \longrightarrow NO_{2(g)} + O_{2(g)}$