【題組】

9. Which of the following statement is correct?
(A) The

law of thermodynamics states that two systems in thermalcontact always reach thermal equilibrium in the end.
(B) The entropy of any macroscopic system never decreases overtime.
(C) The entropy of an idcal gas is doubled if its volume is doubled at the same temperature.
(D) Any irreversibleengine always has a smaller efficiency than any reversible engine.
(E) By choosing a suitable definition of Kelvin, theBoltzmann constant has an exact value that does not have to be determined by experiments.