If the components of air are `N_(2), 78%, O_(2), 21%, Ar, 0-9%` and `CO_(2), 0-1%` by volume, what would be the molecular weight of air?

Explanation

The volume ratio of the gases will be the same as their mole ratio (Avogadro.s principle)
`therefore` mol. Wt of air `=(78 xx 28 + 21 xx 32 + 0.9 xx 40 + 0.1 xx 44)/(78 + 21 + 0.9 + 0.1)`
(`N_(2) = 28, O_(2) = 32, Ar = 40` and `CO_(2) = 44`)