What is the vapour density of $O_2$ gas?

$A_{(g)} \rightleftharpoons 2B_{(g)} + C_{(g)}$
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)

For the reaction $A \rightleftharpoons B + C$,if we start with $2 \ mol$ of $A$ and $0.5 \ mol$ dissociates,what is the degree of dissociation of $A$?

At $200 \, ^\circ C$,the observed vapour density $(V.D.)$ of $PCl_5$ is $60$. The degree of dissociation $(\alpha)$ of $PCl_5$ is ..........$\%$ (Given: Molar mass of $PCl_5 = 208.5 \, g/mol$).

For the reaction $A \rightleftharpoons \frac{1}{2} B + C$,the degree of dissociation $\alpha$ in terms of vapour density $D_t$ (theoretical) and $D_o$ (observed) is given by:

For the reaction $PCl_5 \rightleftharpoons PCl_3 + Cl_2$,the degree of dissociation is inversely proportional to the square root of the system pressure. Assuming constant temperature,if the volume of the system increases to $16$ times its initial volume,the degree of dissociation becomes ....... times.