Question

Photochemical smog occurs in warm, dry and sunny climate. One of the following is not amongst the components of photochemical smog, identify it.

• A. ${\mathrm{SO}}_2$
• B. ${\mathrm{NO}}_2$
• C. ${\mathrm{O}}_3$
• D. Unsaturated hydrocarbon

Answer 1

The correct option is A

${\mathrm{SO}}_2$

The explanation for the correct answer:

Photochemical smog:

1. This smog is basically the mixture of the pollutants which are formed when the Nitrogen oxides and some other volatile organic compounds will react to the sunlight or within the sunlight.
2. After this reaction, there would be a creation of brown haze all over.
3. Nitrogen dioxide coming from the vehicle exhausts is just photolyzed by the ($\mathrm{UV}$) radiations coming directly from the sun, and further will decompose to the Nitrogen oxide with oxygen radical.
4. This whole process would be held in continuation just for the temporary increase in the net ozone production.
5. Reactions involved:-

$\underset{\mathrm{Nitrogen}\mathrm{dioxide}}{{\mathrm{NO}}_2\left(\mathrm{g}\right)}\stackrel{\mathrm{h\nu }}{\to }\underset{\mathrm{Nitric}\mathrm{oxide}}{\mathrm{NO}\left(\mathrm{g}\right)}+\mathrm{O}\left(\mathrm{g}\right)$

$\mathrm{O}\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\leftrightarrow {\mathrm{O}}_3\left(\mathrm{g}\right)$

${\mathrm{O}}_3\left(\mathrm{g}\right)+\mathrm{NO}\left(\mathrm{g}\right)\to {\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

$3{\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{O}}_3\left(\mathrm{g}\right)\to \underset{\mathrm{Formaldehyde}}{3{\mathrm{CH}}_2=\mathrm{O}\left(\mathrm{g}\right)}+3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Therefore, the correct option is (A):- ${\mathrm{SO}}_2$