I read the whole thread and it was worth it, for the laughs.
When the OP said that nitrogen was heavier than air, perhaps he forgot that nitrogen makes up about 78% of the air. Oxygen, a heavier atom than nitrogen, makes up about 21% and argon, a much heavier atom, makes up about 1% or the atmosphere.
The other funny one was the bit about moisture being heavier than the N2 molecule. That's probably why I get getting woken up by huge clouds crashing down to ground do to the heavy water vapor molecule. Whoops, water is H2O so when in a vapor state, such as in humid environments, it's lighter than air.
Argon is a noble gas and does not react with anything, it's completely inert and is 38% denser than air, which is why it makes a better medium in a riflescope than nitrogen. It has low thermal conductivity and that's why you find it in double and triple-pane windows.
BTW, March scopes are filled with argon instead of nitrogen.
