Sea-Level Composition of Air

(in percent by volume at the temperature of 15°C and the pressure of 101325 Pa)

NameSymbolPercent by Volume
Nitrogen N2 78.084 %
OxygenO220.9476 %
ArgonAr0.934 %
Carbon DioxideCO20.0314 %
NeonNe0.001818 %
MethaneCH40.0002 %
HeliumHe0.000524 %
KryptonKr0.000114 %
HydrogenH20.00005 %
XenonXe0.0000087 %

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Science Quote

'For the sake of persons of ... different types, scientific truth should be presented in different forms, and should be regarded as equally scientific, whether it appears in the robust form and the vivid coloring of a physical illustration, or in the tenuity and paleness of a symbolic expression.'

James Clerk Maxwell
(1831-1879)