複選題

45. Consider 1.0 mole of a monatomic ideal gas in a container fitted with a piston. The initial
conditions are V = 5.0 L and P = 4.0 atm at some constant T. These two processes are
performed isothermally:
(a) The external pressure is suddenly changed to 2.0 atm to allow expansion of the gas.
(b) Followed by process (a), the external pressure suddenly changes back to 4.0 atm to
compress the gas.
Which of the following statements about these two processes are NOT TRUE?
(A) In process (a), expansion of the gas is spontaneous.
(B) In process (b), compression of the gas is nonspontaneous.
(C) The sign of free energy change (△G) can be used to predict spontaneity of these two
processes.
(D) In process (a), the change of internal energy (△E) is zero during the gas expansion.

(E) In process (b), the sign of is negative during the gas compression.