The main component of photochemical smog isans.Water vapour Oxides of nitrogenAll of the aboveSulphur dioxide

The main component of photochemical smog is Oxides of nitrogen.

Here's a step-by-step explanation:

1. Photochemical smog is a type of air pollution that is a result of the reaction between sunlight and pollutants like nitrogen oxides and volatile organic compounds.

2. Nitrogen oxides are released from car exhaust, coal power plants, and factory emissions. Volatile organic compounds are released from gasoline, paints, and many cleaning solvents.

3. When the sunlight hits these chemicals, it causes a reaction that forms new compounds, primarily Peroxyacetyl nitrates (PANs) and Ozone.

4. These new compounds create a foggy, often yellowish or brownish haze in the air, which we refer to as photochemical smog.

5. Therefore, the main component of photochemical smog is Oxides of nitrogen.