Ozone depletion is due to the formation of the following compound in Antarctica:

Water is considered to be polluted if the dissolved oxygen $(D.O.)$ content is less than $...$ $ppm$ :

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

Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

Which of the following methods can be used to control water pollution?

Which one of the following statements is $NOT$ correct?