Which of the statements A–D is false?

Question

A. For an isochoric system, WEC=0, but WS is not necessarily equal to zero.
B. For a steady state system, WEC=0, but WS is not necessarily equal to zero.
C. All isothermal systems are adiabatic, but not all adiabatic systems are isothermal.
D. All isolated systems are adiabatic systems, but not all adiabatic systems are isolated systems.
E. None of the above are false.

Answer 1

A. Incorrect. This statement is true. Isochoric means constant volume, which means there can be no expansion work. But an isochoric system can contain moving parts that add or remove shaft work.
B. Incorrect. This statement is true. In a steady state system, all properties of the system are constant with respect to time. Volume is a property of the system; a steady state system cannot be expanding or contracting. But a steady state system can involve shaft work, such as the pump and turbine in a Rankine cycle.
C. Correct. Isothermal systems are not necessarily adiabatic; in fact, adding or removing heat is often precisely the way a system is maintained as isothermal.
D. Incorrect. This statement is true. Isolated systems have neither energy nor mass crossing the boundaries of the system. Thus an isolated system cannot have heat transfer, and is therefore adiabatic. But an adiabatic system that has mass or work entering or leaving is not isolated.
E. Incorrect. Check again. One of the statements is false.
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