|N2||is the normal Nitrogen gas, colourless and odourless.|
|NO + NO2||the 'nitrous vapors', yellow brown, suffocating|
|N2O||a colourless gas, in fact a kind of nerve affecting gas.
It causes strange face contractions (kind of laughing) and it helps to anaestesise people (or animals).
It was found in 1860 and applied, for example, by dentists.