Which of the following is not an air pollutant ?

Options

A. `N_(2)`
B. `N_(2)O`
C. `CO`
D. `NO`

Answer

To determine which of the following is not an air pollutant, we need to analyze the options given. Let's break down the solution step by step.

### Step-by-Step Solution:

1. **Understanding Air Pollutants**:
- Air pollutants are substances in the air that can cause harm to humans, animals, and the environment. Common air pollutants include gases like carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), and particulate matter.

2. **Identifying the Options**:
- The question provides a list of gases, among which we need to identify the one that is not an air pollutant.

3. **Analyzing Nitrogen**:
- Nitrogen (N2) makes up about 78% of the Earth's atmosphere. It is a major component of the air we breathe and is generally considered non-toxic and non-polluting under normal atmospheric conditions.

4. **Examining Other Gases**:
- **Nitrogen Oxides (NOx)**: These are pollutants that can come from vehicle emissions and industrial processes. They contribute to smog and respiratory problems.
- **Carbon Monoxide (CO)**: This is another harmful pollutant that is produced from incomplete combustion of fossil fuels. It binds with hemoglobin in the blood, reducing the blood's ability to carry oxygen.
- **Carbon Dioxide (CO2)**: While it is a natural component of the atmosphere, excessive CO2 due to human activities contributes to global warming and climate change.

5. **Conclusion**:
- Since nitrogen is a natural and abundant component of the atmosphere and does not have harmful effects like the other gases mentioned, it is not considered an air pollutant. Therefore, the correct answer is nitrogen.

### Final Answer:
**Nitrogen is not an air pollutant.**

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