Gas composition
Pure Gas Name Symbol Percent by Volume
Nitrogen N 2 78.084
Oxygen O 2 20.9476
Argon Ar 0.934
Carbon Dioxide CO 2 0.0314
Neon Ne 0.001818
Methane CH 4 0.0002
Helium He 0.000524
Krypton Kr 0.000114
Hydrogen H 2 0.00005
Xenon Xe 0.0000087
Gas composition of air
To give a familiar example , air has a composition of : [ 1 ]
The Gas composition of any gas can be characterised by listing the pure substances it contains, and stating for each substance its proportion of the gas mixture's molecule count.