NEET 2021 Physics and Chemistry

● Tropospheric pollution: In the presence of pollutant, $\mathrm{SO}_{2}$ cunverts into $\mathrm{SO}_{3}$ $2 \mathrm{SO}_{2}+\mathrm{O}_{2} \rightarrow 2 \mathrm{SO}_{3}$ ● In spring season, sunlight breaks $\mathrm{HOCl}$ and $\mathrm{Cl}_{2}$ to give chlorine radicals. $\mathrm{HOCl} \xrightarrow{hv} \overset{\bullet}{\mathrm{O}} \mathrm{H}(\mathrm{g})+\overset{\bullet}{\mathrm{Cl}}(\mathrm{g})$ These chlorine radicals deplete ozone layer ● High level of sulphur causes acid rain which reacts with marble and causes discolouring and disfiguring $\mathrm{CaCO}_{3}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{CaSO}_{4}+\mathrm{H}_{2} \mathrm{O}$ $+ \mathrm{CO}_{2}$ ● A chain reaction occurs from interaction of NO with sunlight in which NO is converted to $\mathrm{NO}_{2}$ which absorb energy from sunlight and breaks into NO and $\mathrm{O}$, which causes photochemical smong. $\mathrm{NO}_{2}(\mathrm{g}) \xrightarrow{hv} \mathrm{NO}(\mathrm{g})+\mathrm{O}(\mathrm{g})$