Which of the following oxides of nitrogen is not common air pollutant ?

Options

A. `NO_2`
B. `N_2O`
C. `NO`
D. `N_2O_5`

Answer

To determine which of the following oxides of nitrogen is not a common air pollutant, we can analyze the options given. The common nitrogen oxides that are recognized as air pollutants include:

1. **N2O (Nitrous Oxide)**: This is a greenhouse gas and contributes to air pollution.
2. **NO (Nitric Oxide)**: This is a common pollutant produced from vehicle emissions and industrial processes.
3. **NO2 (Nitrogen Dioxide)**: This is a significant air pollutant that contributes to smog and respiratory problems.

Now, let's look at the other option:

4. **N2O5 (Dinitrogen Pentoxide)**: This is not commonly found in the atmosphere and is not recognized as a significant air pollutant.

Based on this analysis, we can conclude that:

**Answer**: N2O5 is not a common air pollutant.

### Step-by-Step Solution:

1. **Identify the Oxides of Nitrogen**: List the oxides of nitrogen provided in the question.
- N2O
- NO
- NO2
- N2O5

2. **Research Common Air Pollutants**: Understand which of these oxides are recognized as common air pollutants.
- N2O, NO, and NO2 are known to be common air pollutants.

3. **Analyze the Remaining Option**: Look at N2O5 and determine its status as an air pollutant.
- N2O5 is not commonly found in the atmosphere and does not significantly contribute to air pollution.

4. **Conclude the Answer**: Based on the analysis, conclude which oxide is not a common air pollutant.
- The correct answer is N2O5.