There are compressed $6\mathrm{.}5$ m$3$

$/$min of oxygen from $1$ atmosphere, $27$ oC$,$ to $315$

kPaa by $36$ cm x $36$ cm single$-$stage, single$-$acting, compressor operating at $120$ rpm$.$ If

compression and re$-$expansion processes are isentropic$,$ find a$)$ the volumetric efficiency,

and b$)$ the compressor power input in Hp$.$