Which of the following statements is correct for any thermodynamic system

Options

A. The internal energy changes in all processes
B. Internal energy and entropy are state functions
C. The change in entropy can never be zero
D. The work done in an adiabatic process is always zero

Explanation

To determine which statement is correct for any thermodynamic system, let's analyze each statement one by one:

1. **Internal energy changes in all processes.**
- This statement is incorrect. In an isothermal process, the temperature remains constant, which means that the internal energy of an ideal gas does not change. Therefore, this statement does not hold true for all processes.

2. **Internal energy and entropy are state functions.**
- This statement is correct. Both internal energy and entropy are state functions, meaning their values depend only on the current state of the system (defined by parameters such as temperature, pressure, and volume) and not on the path taken to reach that state.

3. **Change in entropy can never be zero.**
- This statement is incorrect. The change in entropy can be zero in a reversible process where the system returns to its original state, or in an isolated system where no processes are occurring. Thus, it is not true that the change in entropy can never be zero.

4. **Work done in an adiabatic process is always zero.**
- This statement is incorrect. In an adiabatic process, there is no heat exchange with the surroundings (Q = 0), but work can still be done on or by the system. Therefore, the work done is not necessarily zero.

Based on the analysis above, the correct statement for any thermodynamic system is:

**Internal energy and entropy are state functions.**