Answer
True, the volume increases by 50%
Work Step by Step
We have 2 CO + O2 --> 2 CO2
In this reaction, we go from 3 moles on the left to 2 moles on the right.
The ideal gas law is PV = nRT
we are told that the piston maintains constant pressure and constant temperature. Therefore, the only thing changing is the number of moles, n, from 3 to 2, which means the volume must increase from 2 to 3. If it was originally 2 and it increases to 3, this is an increase of 1, which is an increase of 50%.