When a bottle of perfume is opened in a closed room of $1000\,m^3$,the fragrance spreads throughout the room. Which property of gases is responsible for this?

The rate of diffusion of $SO_3$,$CO_2$,$PCl_3$ and $SO_2$ gases are in the following order:

$A$ gas diffuses $1/5$ times as fast as hydrogen. Its molecular weight is

Explain the vapour pressure of a liquid.

If $P_1$ is the partial pressure of a gas and $x_1$ is its mole fraction in a mixture,then the correct relation between $P_1$ and $x_1$ is:

$A$ 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 $torr$?