Which of the following is true about photochemical smog ?

Options

A. It is reducing in nature
B. It is formed in water
C. It is a mixture of smoke and fog
D. It causes irritation in eyes.

Answer

To determine which statement is true about photochemical smog, we will evaluate each of the provided options based on the characteristics of photochemical smog.

### Step-by-Step Solution:

1. **Understanding Photochemical Smog**:
- Photochemical smog is a type of air pollution that occurs in the presence of sunlight. It is primarily formed when sunlight reacts with pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the atmosphere.

2. **Evaluating the Statements**:
- **Statement A**: "It is reducing in nature."
- This statement is **false**. Photochemical smog is known to have an oxidizing nature due to the presence of ozone (O3) and other oxidants.

- **Statement B**: "It is formed in water."
- This statement is **false**. Photochemical smog does not form in water; it forms in the atmosphere under specific climatic conditions (warm, dry, and sunny).

- **Statement C**: "It is a form of smoke, a mixture of smoke and coke."
- This statement is **false**. Photochemical smog is not a mixture of smoke and coke; it consists of various pollutants like ozone, nitrogen oxides, and other organic compounds, but not coke.

- **Statement D**: "It causes irritation in eyes."
- This statement is **true**. Photochemical smog can cause various health issues, including irritation in the eyes, throat, and respiratory problems due to the high concentration of harmful pollutants.

3. **Conclusion**:
- The correct answer is **Statement D**: "It causes irritation in eyes."