$CH_4$ diffuses two times faster than a gas $X$. The number of molecules present in $32 \ g$ of gas $X$ is ($N$ is Avogadro number).

An empty $LPG$ cylinder weighs $14.8 \ kg$. When full,it weighs $29.0 \ kg$ and shows a pressure of $3.47 \ atm$. In the course of use at ambient temperature,the mass of the cylinder is reduced to $23.0 \ kg$. The final pressure inside of the cylinder is $....... \ atm$. (Nearest integer)
(Assume $LPG$ to be an ideal gas)

$A$ $x : 1$ molar mixture of $He$ and $CH_4$ is contained in a vessel at $20 \ bar$ pressure. Due to a hole in the vessel,the gas mixture leaks out. If the composition of the mixture effusing out initially is $8 : 1$,then the value of $x$ will be

At $300 \ K$ and $760 \ torr$ pressure,the density of a mixture of $He$ and $O_2$ gases is $0.543 \ g \ L^{-1}$. The mass percent of oxygen is approximately $(R = 0.0821 \ L \ atm \ K^{-1} \ mol^{-1})$

Which of the following statements is correct?

Assertion : Ice melts faster at high altitude.
Reason : At high altitude,atmospheric pressure is high.