Photochemical smog consists of excessive amount of X in addition to aldehydes, ketones, PAN etc.X is

Options

A. methane
B. carbon monoxide
C. carbon dioxide
D. ozone

Explanation

To solve the question regarding photochemical smog, we need to identify the component "X" that is present in excessive amounts along with aldehydes, ketones, and PAN (peroxyacyl nitrate).

### Step-by-Step Solution:

1. **Understanding Photochemical Smog**:
Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants such as volatile organic compounds (VOCs) and nitrogen oxides (NOx). This reaction produces secondary pollutants.

2. **Identifying Components of Photochemical Smog**:
The main components of photochemical smog include:
- Nitrogen dioxide (NO2)
- Ozone (O3)
- Aldehydes
- Ketones
- Peroxyacyl nitrate (PAN)

3. **Analyzing the Role of Ozone**:
Ozone is a significant component of photochemical smog. It is formed when sunlight reacts with pollutants like NOx and VOCs. Ozone can oxidize unsaturated hydrocarbons, leading to the formation of aldehydes and ketones.

4. **Recognizing Excessive Amounts**:
In the context of photochemical smog, ozone is often found in excessive amounts. This is because it is a secondary pollutant formed from the reaction of primary pollutants in the presence of sunlight.

5. **Conclusion**:
Based on the analysis, the excessive amount of "X" in photochemical smog, in addition to aldehydes, ketones, and PAN, is ozone (O3).

### Final Answer:
X is Ozone (O3).

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