The formation of `O_3` in upper part of atmosphere is catalyzed by

Options

A. `N_2`
B. `NO`
C. CO
D. `CO_2`

Answer

To solve the question regarding the catalysis of ozone formation in the upper atmosphere, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Ozone Formation**:
Ozone (O₃) is formed in the upper atmosphere when oxygen molecules (O₂) are exposed to ultraviolet (UV) light. The energy from the UV light causes the oxygen molecules to dissociate into individual oxygen atoms (O).

2. **Role of Catalysts**:
Catalysts are substances that speed up a chemical reaction without being consumed in the process. In the case of ozone formation, certain substances can act as catalysts to facilitate the reaction.

3. **Identifying the Catalyst**:
It is known that nitrogen oxides (NOx), particularly nitrogen dioxide (NO₂), can act as a catalyst in the formation of ozone. When NO₂ is present in the atmosphere and exposed to sunlight, it can help convert O₂ into O₃.

4. **Evaluating Options**:
The question provides multiple-choice options. We need to identify which one correctly represents the catalyst involved in the formation of ozone:
- Option 1: Not specified in the transcript, but we can assume it is incorrect.
- Option 2: NO₂ (Nitrogen Dioxide) - This is the correct answer.
- Option 3: CO (Carbon Monoxide) - This is incorrect.
- Option 4: CO₂ (Carbon Dioxide) - This is also incorrect.

5. **Conclusion**:
Based on the information provided, the formation of ozone in the upper part of the atmosphere is catalyzed by nitrogen dioxide (NO₂).

### Final Answer:
The formation of O₃ in the upper part of the atmosphere is catalyzed by **NO₂ (Nitrogen Dioxide)**.

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