If the vapor density of a volatile substance relative to $CH_4$ is $4$,then find the molecular mass of that substance.

$A$ mixture of $NO_2$ and $N_2O_4$ has a vapour density of $38.3$ at $300 \ K$. What is the number of moles of $NO_2$ in $100 \ g$ of the mixture?

The degree of dissociation of $PCl_5$ $(\alpha)$ obeying the equilibrium $PCl_5 \rightleftharpoons PCl_3 + Cl_2$ is related to the pressure at equilibrium $(P)$ by:

If in the reaction $N_2O_4 \rightleftharpoons 2NO_2$,$\alpha$ is the fraction of $N_2O_4$ that dissociates,then the total number of moles at equilibrium is:

$3.2 \text{ moles of hydrogen iodide are heated in a closed vessel at } 444^{\circ}C \text{ until equilibrium is reached. If the degree of dissociation at this temperature is } 22\%, \text{ then the number of moles of hydrogen iodide remaining at equilibrium will be:}$

$A_{(g)} \rightleftharpoons 2B_{(g)} + C_{(g)}$
For the given reaction,if the initial pressure is $450 \ mm \ Hg$ and the total pressure at time $t$ is $720 \ mm \ Hg$ at a constant temperature $T$ and constant volume $V$. The fraction of $A_{(g)}$ decomposed under these conditions is $x \times 10^{-1}$. The value of $x$ is $......$. (nearest integer)