The photochemical smog does not generally contain

We need to identify which compound is generally NOT found in photochemical smog.

Photochemical smog is formed by the action of sunlight on nitrogen oxides ($$NO_x$$) and volatile organic compounds (VOCs) released mainly by automobile exhaust.

The key components of photochemical smog include:

- Nitrogen oxides: $$NO$$ and $$NO_2$$

- Ozone ($$O_3$$)

- Formaldehyde ($$HCHO$$) and other aldehydes

- Peroxyacetyl nitrate (PAN)

- Various organic peroxides

$$SO_2$$ (sulphur dioxide) is a component of classical smog (also called London smog or reducing smog), which is caused by burning of coal and is associated with cool, humid conditions. It is NOT a typical component of photochemical smog.

Hence, the correct answer is Option C.