Atmospheric Pollution

To determine which oxide of nitrogen is not a common pollutant introduced into the atmosphere due to natural and human activity, let's evaluate each option:

1. N₂O₅ (Dinitrogen pentoxide): N₂O₅ is not commonly found in the atmosphere as it is a less stable compound compared to other nitrogen oxides. It typically exists in atmospheric reactions as a transient species rather than being directly emitted as a pollutant. Thus, it is not considered a common atmospheric pollutant from natural or anthropogenic sources.
2. N₂O (Nitrous oxide): N₂O is produced naturally in soils by biological processes and can also be emitted from agricultural and industrial activities. It is a well-known greenhouse gas and is considered a significant atmospheric pollutant.
3. NO₂ (Nitrogen dioxide): NO₂ is a common air pollutant that comes from vehicle emissions, industrial activities, and burning of fossil fuels. It is a significant contributor to air pollution and forms acid rain and photochemical smog.
4. NO (Nitric oxide): NO is emitted from combustion processes, including engines and power plants, and it rapidly reacts in the atmosphere to form NO₂. It is also a common pollutant.

Considering the descriptions above, N₂O₅ is not a common atmospheric pollutant introduced by natural and human activities. It is primarily formed through reactions involving other nitrogen oxides and is typically found in the atmosphere only in minimal concentrations.