Which of the following chemical reactions is/are related to smog formation in the troposphere?
- $\mathrm{CFCl}_{3}+h v \rightarrow \mathrm{CFCl}_{2}+\mathrm{Cl} \cdot$
- $\mathrm{CH}_{3} \mathrm{O}_{2}+\mathrm{NO}+\mathrm{O}_{2} \rightarrow \mathrm{HCHO}+\mathrm{HO}_{2}+\mathrm{NO}_{2}$
- $\mathrm{NO}_{2}+\mathrm{O}_{2}+h v \xrightarrow{M} \mathrm{O}_{3}+\mathrm{NO}$
- $\mathrm{CH}_{4}+8 \mathrm{O}_{2} \rightarrow \mathrm{CO}+\mathrm{H}_{2} \mathrm{O}+2 \mathrm{OH} \cdot+4 \mathrm{O}_{3}$
