Name two phenomena that can be explained on the basis of surface tension.

$A$ mixture of $N_2$ and $Ar$ gases in a cylinder contains $7 \ g$ of $N_2$ and $8 \ g$ of $Ar$. If the total pressure of the mixture of gases in the cylinder is $27 \ bar$,the partial pressure of $N_2$ is $......... \ bar$.
[Use atomic masses (in $g \ mol^{-1}$) : $N=14, Ar=40$]

What is the ratio of the rate of diffusion of oxygen $(O_2)$ to hydrogen $(H_2)$?

Dalton's law of partial pressure is not applicable for which of the following mixtures?

It takes $38 \, s$ for $1 \, mol$ of $N_2$ gas to effuse through a pinhole at a pressure of $0.8 \, atm$. It takes $57 \, s$ for $1 \, mol$ of an unknown gas $X$ to effuse through the same pinhole at a pressure of $1.6 \, atm$. Calculate the molar mass of $X$.

$A$ closed container contains a mixture of non-reacting gases $A$ and $B$. The partial pressures of $A$ and $B$ are $4.5 \ bar$ and $5.5 \ bar$ respectively. Find the mole fractions of $A$ and $B$ respectively.