Final answer:
The change in internal energy of a perfect gas that expands reversibly and adiabatically to twice its volume is that it remained constant.
Step-by-step explanation:
The change in internal energy of a perfect gas that expands reversibly and adiabatically to twice its volume can be inferred as c) It remained constant. In an adiabatic process, there is no heat transfer, so the change in internal energy can be attributed solely to work done on or by the gas.
As the volume doubles, the work done by the gas is equal to the decrease in its internal energy, keeping the internal energy constant. This is in line with the first law of thermodynamics, which states that the change in internal energy is equal to the heat added to or removed from the system minus the work done by or on the system.