Atmospheric air has `78 % N_(2) , 21 % O_(2) , 0.9 % Ar and 0.1 % CO_(2)` by volume. What is the molecular mass of air in the atmosphere ?

Explanation

Molar mass of mixture of gases in air
`= sum("% of each gas")/(100)xx"Molar mass of the gas"`
`=(78)/(100)xx(28u)+(21)/(100)xx(32u)+(0.9)/(100)xx(40u)+(0.1)/(100)xx(44u)`
`=21.84+6.72+0.36+0.04=28.96 u`.