(a) $TV^{\gamma - 1} =$ constant $\Rightarrow \frac{T_{2}}{T_{1}} = \left( \frac{V_{1}}{V_{2}} \right)^{\gamma - 1}$
$\Rightarrow T_{2} = T_{1}\left( \frac{V_{1}}{V_{2}} \right)^{\gamma - 1}$
$\Rightarrow T_{2} = 300\left( \frac{1}{2} \right)^{0.4} = 227.36\ K$