The molar heat capacity at constant pressure is represented by Cp. While Cv is the representation of molar heat capacity at constant volume.
When a gas is heated at a constant volume, the work done on the gas increases the internal energy of the system. At constant pressure, when a gas is heated, work is done to overcome the pressure and there is an expansion in the volume with an increase in the internal energy of the system. Therefore, it can be said that Cp is greater than Cv.