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:

Equal volume of $2$ gases $A$ and $B$ diffuse in $20 \ s$ and $10 \ s$ respectively. If molar mass of $A$ is $80$,then the molar mass of $B$ is:

For the diffusion of a gas at pressure $P$,the rate of diffusion is expressed by :

At $T(K)$,a gaseous mixture containing $H_2, He$ and $O_2$ exerted a pressure of $1 \ bar$. The weight percentage of $H_2$ and $He$ is $20$ and $16$ respectively. The partial pressure (in bar) of $H_2, He$ and $O_2$ is respectively

$50 \ mL$ of hydrogen gas diffuses through a small hole in a container in $20 \ min$. How much time (in $min$) will $40 \ mL$ of oxygen take to diffuse under the same conditions?

At higher altitudes,the boiling point of water lowers because: