Answer
Please see the work below.
Work Step by Step
We know that:
$n=\frac{PV}{RT}$
$n=\frac{0.97\times 5.4}{0.0821\times 317}$
$n=0.20moles$
Now $M=\frac{m}{n}$
We plug in the known values to obtain:
$M=\frac{7.10}{0.20}=35.1\frac{g}{mol}$