(c) $\frac{T_{2}}{T_{1}} = \left( \frac{V_{1}}{V_{2}} \right)^{\gamma - 1} = 2 \Rightarrow \left( \frac{V_{2}}{V_{1}} \right)^{\gamma - 1} = \frac{1}{2} \Rightarrow \frac{V_{2}}{V_{1}} = \left( \frac{1}{2} \right)^{\frac{1}{\gamma - 1}} < \frac{1}{2}$
$\Rightarrow V_{2} < \frac{V_{1}}{2}$