Which of the following is secondary pollutant

Options

A. PAN
B. CO
C. `NO_(2)`
D. `SO_(2)`

Answer

To determine which of the following is a secondary pollutant, we need to understand the difference between primary and secondary pollutants.

### Step-by-Step Solution:

1. **Define Primary Pollutants**: Primary pollutants are substances that are directly emitted into the atmosphere from sources such as vehicles, factories, and natural events. Examples include carbon monoxide, nitrogen dioxide, and sulfur dioxide.

2. **Define Secondary Pollutants**: Secondary pollutants are not emitted directly. Instead, they form in the atmosphere through chemical reactions between primary pollutants and other atmospheric components.

3. **Analyze the Options**:
- **Option 1: PAN (Pyroxyacetyl Nitrate)**: This is a secondary pollutant because it forms when primary pollutants like nitrogen oxides react with volatile organic compounds (VOCs) in the presence of sunlight.
- **Option 2: Carbon Monoxide**: This is a primary pollutant, as it is directly emitted from sources like vehicles and industrial processes.
- **Option 3: Nitrogen Dioxide**: This is also a primary pollutant, produced from combustion processes.
- **Option 4: Sulfur Dioxide**: This is another primary pollutant, primarily released from burning fossil fuels.

4. **Conclusion**: Based on the definitions and analysis, the only secondary pollutant among the options provided is **Option 1: PAN (Pyroxyacetyl Nitrate)**.

### Final Answer:
The secondary pollutant is **Option 1: PAN (Pyroxyacetyl Nitrate)**.

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