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Periodic table

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Air is made up of a mixture of gases. The major component of air is nitrogen gas followed by oxygen

Name Chemical formula Percentage composition by volume  
Nitrogen
N2
78.1 %  
Oxygen
O2
20.9 %  
Argon
Ar
0.9 %  
Carbon dioxide
CO2
0.03 %  
Neon
Ne
0.002 %  
Helium
He
0.0005 %  
Methane
CH4
0.0002 %  
Krypton
Kr
0.0001 %  
Hydrogen
H2
0.00005 %  
Xenon
Xe
0.000009 %  

The first two gases nitrogen and oxygen make up 99.0% of the atmosphere by volume.

Nitrogen is fairly inert because of its strong triple bond holding the atoms together in the molecule.

Oxygen gas is produced by photosynthesis and removed by combustion and respiration.