Part A
Which of the following statements is a consequence of the second law of thermodynamics? (There may be more than one correct choice.)
A: The efficiency of a heat engine can never be greater than unity.
B: Heat can never flow from a cold object to a hot object unless work is done.
C: Energy is conserved in all thermodynamics processes.
D: Even a perfect heat engine cannot convert all of the heat put into it to work.
Type alphabetically the letters corresponding to the correct statements. For instance, if you think that only statements A, B, and C are consequences of the law, type ABC.
