Let's check it:
First, we have this formula
[tex]\frac{P_o*V_o}{\eta_o*T_o}=\frac{P_f*V_f}{\eta_f*T_f}[/tex]
The pressures are the same so we can cancel, but don't leave and don't enter any mass so, let's check what stay.
[tex]\frac{V_o}{T_o}=\frac{V_f}{T_f}[/tex]
We know that the final temperature is 2 times the initial temperature
so we can write
[tex]T_f=2T_o[/tex]
Replacing
[tex]\frac{V_o}{T_o}=\frac{V_f}{2T_o}[/tex]
[tex]V_o=\frac{V_f}{2}[/tex]
So
[tex]\boxed{\boxed{\Huge{V_f=2V_o}}}[/tex]
Therefore the volume is doubled.