What symbol represents the heat capacity at constant volume?

The symbol that represents the heat capacity at constant volume is ( C_V ). Heat capacity is a property that indicates the amount of heat required to change the temperature of a substance by one degree. The subscript ( V ) specifically indicates that this measurement is taken at constant volume, which means that any changes in heat capacity will occur without any work being done on or by the system.

In thermodynamic systems, it is crucial to differentiate between heat capacities measured under different conditions, such as constant pressure (represented by ( C_p )) and constant volume (represented by ( C_V )). When heat is added to a system at constant volume, the internal energy of the system increases, and this relationship can be quantitatively expressed through ( C_V ). In contrast, ( C_p ) would be used when the pressure remains constant while heat is added.

The other symbols have different meanings: ( \Delta H ) represents the change in enthalpy, which is related to heat capacity under constant pressure conditions, and ( U ) represents internal energy, a state function that reflects the total energy of the system, not specifically related to heat capacity. Thus, the correct answer providing the symbol for heat capacity at constant volume is