the density of moist or humid air is less than the density of dry air why - Physics -

Question

the density of moist or humid air is less than the density of
dry air why

Rahul Verma · Accepted Answer

density=Mass/Volume
The molecular weights of O2 , N2 and
H2O are 32, 28, and 18 atomic mass units for a certain
volume in moist air H2O molecule will be substitute for
a O2 or N2 molecule which will decrease the
total mass of air for that volume of air Since the volume is same
for both moist air and dry air the density of water-containing air
must be less than the density of dry air