Phosphine decomposes at $300 \ K$ and $3 \ atm$ as
$4PH_{3(g)} \rightleftharpoons P_{4(g)} + 6H_{2(g)}$
Calculate the vapour density of phosphine if it dissociates to the extent of $30 \%$.

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

For the reaction $N_{2(g)} + O_{2(g)} \rightleftharpoons 2NO_{(g)}$; if $K_C = 2$,then the degree of dissociation of $O_2$ is:

$4 \ mol$ of $PCl_5$ is heated in a closed vessel at a constant temperature. If the degree of dissociation for $PCl_5$ is $0.5$,what will be the total number of moles at equilibrium?

At temperature $T$,the dissociation equilibrium of $AB_{2(g)}$ is given as: $2AB_{2(g)} \rightleftharpoons 2AB_{(g)} + B_{2(g)}$. If the degree of dissociation $x$ is very small compared to $1$,then the expression for the equilibrium constant $K_p$ in terms of $x$ and total pressure $P$ is:

$2SO_3 \rightleftharpoons 2SO_2 + O_2$. Initially,$3$ moles of $SO_3$ were heated. If the degree of dissociation of $SO_3$ is $40\%$,find the total number of moles at equilibrium.