# Internal energy of a system remains constant when it undergoes?

(A) for cyclic process only (B) for isothermal process only (C) for adiabatic process only (D) any process in which the heat given out by the system is equal to the work done on the system

The internal energy change depends only on the final and initial state of the system, it is zero for the cyclic and isothermal processes.
However, in general, it is zero for any process in which the heat given out is equal to the work done on the system.