All other variables equal,humid air is less dense than drier air because:
A)water molecules are negatively charged and thus repel other molecules.
B)the molecular weight of water is less than that of either diatomic oxygen or diatomic nitrogen.
C)some of the water in humid air will condense, and the latent heat released will expand the air.
D)water molecules have a lower average velocity than does diatomic nitrogen.

Question

Quizplus · Accepted Answer

The molecular weight of water (H2O, approximately 18 g/mol) is less than that of the primary components of air, diatomic oxygen (O2, approximately 32 g/mol) and diatomic nitrogen (N2, approximately 28 g/mol). Therefore, when water vapor is added to air, it replaces some of the heavier molecules, making the humid air less dense.

All Other Variables Equal,humid Air Is Less Dense Than Drier