$A$ bottle of ammonia and a bottle of dry hydrogen chloride connected through a long tube are opened simultaneously at both ends. The white ammonium chloride ring first formed will be:

$A$ $He$ atom is twice as heavy as a hydrogen molecule. At $25\,^oC$,the kinetic energy of a $He$ atom is:

$X$ 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 $2$.

At constant volume,for a fixed number of moles of a gas,the pressure of the gas increases with an increase in temperature due to:

Which of the following describes an ideal gas?
$(i)$ The volume occupied by a gas molecule is negligible.
$(ii)$ The collision between ideal gas molecules are elastic.
$(iii)$ Particles are very small compared to the distance between each other.

Assertion $(A)$ At $300 \ K$, kinetic energy of $16 \ g$ of methane is equal to the kinetic energy of $32 \ g$ of oxygen.
Reason $(R)$ At constant temperature, kinetic energy of one mole of all gases is equal.