PAN (Peroxyacety Nitrate) is an important constituent of photochemical smog is a

Options

A. primary pollutant
B. secondary pollutant
C. natural pollutant
D. Corrollary pollutant

Answer

To determine the classification of PAN (Peroxyacetylnitrate) as an important constituent of photochemical smog, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding PAN**:
- PAN stands for Peroxyacetylnitrate, which is a chemical compound that plays a significant role in air pollution, particularly in photochemical smog.

2. **Identifying Pollutants**:
- Pollutants can be classified into two main categories: primary pollutants and secondary pollutants.
- **Primary pollutants** are those that are directly emitted into the atmosphere from sources like vehicles, industrial processes, and natural events.
- **Secondary pollutants** are not directly emitted but are formed through chemical reactions in the atmosphere, often involving primary pollutants.

3. **Formation of PAN**:
- PAN is formed when nitrogen oxides (NOx) react with hydrocarbons (HC) in the presence of sunlight.
- This reaction is a photochemical process, which means it requires light to occur.

4. **Classifying PAN**:
- Since PAN is produced from the reaction of primary pollutants (NOx and hydrocarbons), it is classified as a secondary pollutant.
- Therefore, the correct classification of PAN in the context of photochemical smog is that it is a secondary pollutant.

5. **Evaluating Options**:
- Option 1: Primary pollutant - Incorrect, as PAN is formed from primary pollutants.
- Option 2: Secondary pollutant - Correct, as PAN is a result of reactions involving primary pollutants.
- Option 3: Natural pollutant - Incorrect, as PAN does not occur naturally but is formed through human activities.
- Option 4: Corollary pollutant - Incorrect, as this term is not commonly used in the context of air pollution classification.

### Conclusion:
The correct answer is that PAN (Peroxyacetylnitrate) is a **secondary pollutant**.

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