Question

Dry $O_2$ is lighter than moist $O_2$.

• A. True
• B. False

Answer 1

The correct option is B False

The given statement is False.
Dry $O_2$ is heavier than moist $O_2$.
$PM=dRT$
Thus,density is directly proportional to the molecular weight.
The molecular weights of $O_2$ and $H_{2}O$ are 32 g/mol and 18 g/mol respectively. Hence, the average molecular weight of moist $O_2$ is less than the molecular weight of dry $O_2$. Dry air consists mostly of nitrogen and oxygen molecules. This means that moist air has heavier molecules replaced by lighter molecules.

Hence, dry $O_2$ is heavier than moist $O_2$.