$\left(\frac{\mathrm{nRT}}{\mathrm{V}}\right)^{2} \mathrm{V}=\mathrm{constant}$
$\frac{\mathrm{T}^{2}}{\mathrm{V}}=\mathrm{constant}$
$\frac{\mathrm{T}_{1}^{2}}{\mathrm{V}_{1}}=\frac{\mathrm{T}_{2}^{2}}{\mathrm{V}_{2}} \quad \Rightarrow \quad \mathrm{T}_{2}^{2}=\frac{\mathrm{V}_{2}}{\mathrm{V}_{1}} \mathrm{T}_{1}^{2}=2 \mathrm{T}_{0}^{2}$
$\Rightarrow \mathrm{T}_{2}=\sqrt{2} \mathrm{T}_{0}$




$V\propto {T^{\frac{2}{3}}}$ $[R = 1.99\ cal/mol-K]$