You have two identical containers at a fixed temperature. In one you have water vapor (H2O) and in the other you have carbon dioxide (CO2). In the high-temperature, classical limit for vibrations and rotations, meaning that (rotation angle << T) and (vibration angle <
The molar heat capacity of the water is larger than the molar heat capacity of the carbon dioxide.
The molar heat capacity of the carbon dioxide is larger than the molar heat capacity of the water
The molar heat capacity of the water and the carbon dioxide are the same.