To determine which oxide of nitrogen is not a common pollutant introduced into the atmosphere,$\\$we need to analyze each option.$\\$Option 1: $$N$_2$O$\\$• Nitrous oxide (N$_2$O$)$ is a greenhouse gas and is released from agricultural activities,$\\$ combustion of fossil fuels, and certain industrial processes. It is a common atmospheric pollutant.$\\$Option 2: $$NO$_2 \\$• Nitrogen dioxide (NO$_2)$ is a significant air pollutant resulting from vehicle emissions,$\\$ power plants, and industrial activities. It is a common atmospheric pollutant.$\\$Option 3: $$N$_2$O$_5 \\$• Dinitrogen pentoxide (N$_2$O$_5)$ is not typically found as a pollutant in the atmosphere.$\\$ It is more of a laboratory chemical and does not have significant natural or anthropogenic sources.$\\$Option 4: $$NO$\\$• Nitric oxide (NO) is a common pollutant produced by combustion processes,$\\$ such as those in vehicles and power plants. It is a common atmospheric pollutant.$\\$Based on the analysis, the oxide of nitrogen that is not a common pollutant introduced into the atmosphere$\\$both due to natural and human activity is $$N$_2$O$_5. \\$Therefore, the correct option is 3.