Internal energy and pressure for unit volume of gas are related by

Which of the following is an incorrect postulate of the kinetic molecular theory of gases?

Which is not true in case of an ideal gas?

Internal energy and pressure of a gas per unit volume are related as

$X$ and $Y$ are two volatile liquids with molar weights of $10 \ g \ mol^{-1}$ and $40 \ g \ mol^{-1}$ respectively. Two cotton plugs,one soaked in $X$ and the other soaked in $Y$,are simultaneously placed at the ends of a tube of length $L = 24 \ cm$. The tube is filled with an inert gas at $1 \ atmosphere$ pressure and a temperature of $300 \ K$. Vapours of $X$ and $Y$ react to form a product which is first observed at a distance $d \ cm$ from the plug soaked in $X$. Take $X$ and $Y$ to have equal molecular diameters and assume ideal behaviour for the inert gas and the two vapours.
$1.$ The value of $d$ in $cm$,as estimated from Graham's law,is:
$(A) \ 8 \ (B) \ 12 \ (C) \ 16 \ (D) \ 20$
$2.$ The experimental value of $d$ is found to be smaller than the estimate obtained using Graham's law. This is due to:
$(A)$ larger mean free path for $X$ as compared to that of $Y$.
$(B)$ larger mean free path for $Y$ as compared to that of $X$.
$(C)$ increased collision frequency of $Y$ with the inert gas as compared to that of $X$ with the inert gas.
$(D)$ increased collision frequency of $X$ with the inert gas as compared to that of $Y$ with the inert gas.
Give the answer for question $1$ and $2$.

The average kinetic energy of an ideal gas per molecule in $SI$ units at $25\,^oC$ will be