Under similar conditions of temperature and pressure,$50 \ mL$ of gas $A$ diffuses through a hole in the same time that $40 \ mL$ of gas $B$ diffuses. If the molar mass of gas $A$ is $64$,what is the molar mass of gas $B$?

At a certain temperature,the time required for the complete diffusion of $200 \ mL$ of $H_2$ gas is $30 \ min$. The time required for the complete diffusion of $50 \ mL$ of $O_2$ gas at the same temperature will be: (in $min$)

$A$ sample of air contains $N_2, O_2$ and $H_2O$. It is saturated with water vapor and the total pressure is $640 \, torr$. The vapor pressure of water is $40 \, torr$ and the molar ratio of gases ${N_2}:{O_2}$ is $3:1$. What is the partial pressure of $N_2$ in the sample in $torr$?

What is the boiling point of $SO_2$ gas (in $K$)?

Helium is added to the oxygen supply used by deep sea divers because

Why are liquids and gases categorised as fluids?