You must be thinking of water. It varies a lot, but can be up to about 4%.
Oxygen.
balls
The gas which makes up the greatest percentage of earth's atmosphere is nitrogen with 78.08%.
Nitrogen makes up about 79% of the atmosphere.
N2-Nitrogen
argon
Oxygen.
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Nitrogen, it actually makes up just over 78% of the Earths atmosphere by volume.
Nitrogen makes up most of our atmosphere. Second is Oxygen.
Oxygen (O2)
CARBONDIOXIDE
Nitrogen makes up 78% of the Earth's atmosphere. Oxygen makes up about 21%.
Nitrogen Gas makes up about 80% of Earths atmosphere with Oxygen making up most of the rest (20%).
The gas which makes up the greatest percentage of earth's atmosphere is nitrogen with 78.08%.
gas-gas
Nitrogen makes up about 79% of the atmosphere.