What is the vapour density of pure ozone $(O_3)$?

For which of the following reactions,the degree of dissociation cannot be calculated from the vapour density data?
$I. \ 2HI_{(g)} \rightleftharpoons H_{2(g)} + I_{2(g)}$
$II. \ 2NH_{3(g)} \rightleftharpoons N_{2(g)} + 3H_{2(g)}$
$III. \ 2NO_{(g)} \rightleftharpoons N_{2(g)} + O_{2(g)}$
$IV. \ PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$

$A$ 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?

Total number of moles for the reaction $2HI \rightleftharpoons H_2 + I_2$ at equilibrium,if $\alpha$ is the degree of dissociation,is:

Which of the following equations is correct for the vapour density of completely dissociated ammonium chloride?

At $T$ $K$,consider the following gaseous reaction,which is in equilibrium: $N_2O_5 \rightleftharpoons 2NO_2 + \frac{1}{2}O_2$. What is the fraction of $N_2O_5$ decomposed at constant volume and temperature,if the initial pressure is $300 \ mm \ Hg$ and pressure at equilibrium is $480 \ mm \ Hg$? (Assume all gases as ideal)