PAN is one of the constituents of photochemical smog.(T/F)

Answer

To determine whether the statement "PAN is one of the constituents of photochemical smog" is true or false, we can follow these steps:

### Step-by-Step Solution:

1. **Identify PAN**: PAN stands for Peroxyacetyl Nitrate. It is a chemical compound that can be formed in the atmosphere.

2. **Understand Photochemical Smog**: Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs). This reaction leads to the formation of secondary pollutants.

3. **Identify Constituents of Photochemical Smog**: The major constituents of photochemical smog include nitrogen oxides (NOx), ozone (O3), and unburnt hydrocarbons. These pollutants react under sunlight to form various secondary pollutants, including PAN.

4. **Formation of PAN**: PAN is formed when nitrogen oxides (NOx) react with unburnt hydrocarbons in the presence of sunlight. This reaction is part of the complex series of reactions that occur in photochemical smog.

5. **Conclusion**: Since PAN is formed as a result of reactions involving the major pollutants of photochemical smog, we can conclude that PAN is indeed a constituent of photochemical smog.

Thus, the statement "PAN is one of the constituents of photochemical smog" is **True**.

### Final Answer:
**True**