a factor of $2$ in an expansion against an external pressure of zero $(0).$

$5$

Suppose a perfect gas having $Cv,m=1\mathrm{.}50R$ undergoes the reversible process

$1231.$

The description of the states is as follows: State $1$: $1\mathrm{.}2Ar(g,\frac{12\mathrm{.}5}{b}ar,1L),$

State $2$: $1\mathrm{.}2$ Ar $($g$,37\mathrm{.}5$ bar, $1$ L$),$ State $3$: $1\mathrm{.}2$ Ar $($g$,12\mathrm{.}5$ bar, $3$ L$)$

a$)$ Show the net work on an indicator diagram.

$[3]$

b$)$ Show that $S=0$ for the cycle.

$10$

Consider the decomposition of phosphorus pentachloride represented as: