Write four main properties of gases.

Write the formula to calculate the pressure of a dry gas collected over water.

The rate of diffusion of a gas is inversely proportional to

When $CH_4$ gas is collected over water,the total pressure is $735 \ torr$ and the temperature is $292 \ ^\circ C$. If the vapor pressure of water at $292 \ ^\circ C$ is $30 \ torr$,then the pressure exerted by the dry methane gas will be .......... $torr$.

The normal boiling point of water at $760 \, mm$ is $373 \, K$. The vapor pressure of water at $298 \, K$ is $23 \, mm$. If the enthalpy of vaporization is $40.656 \, kJ/mol$,then its boiling point at $23 \, mm$ pressure will be ........... $K$.

The interaction energy of $London$ forces between two particles is proportional to $r^{x}$,where $r$ is the distance between the particles. The value of $x$ is: