What is the fourth most gas in air?

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August 19, 2008 12:39PM

Two answers to that one: no question that nitrogen and oxygen are the top two.

The next two are argon (about 1%) and CO2 (at .03%) ... in dry air.

The trickster is water vapor. It varies with temperature and availability of water for evaporation. It can be either number 3 or number 4 or number 5.