The problem that arose my confusion:
One mole of a monatomic ideal gas undergoes a cyclic process as shown in the figure (where $V$ is the volume and $T$ is the temperature). Which of the statements below is (are) true?
(A) Process I is an isochoric process
(B) In process II, gas absorbs heat
(C) In process IV, gas releases heat
(D) Processes I and III are not isobaric
The correct options are
(B) (C) (D),
and I understand
how (A) is false.
My confusion: I was having issues when dealing with the thermodynamical process that the gas undergoes during process II. It seems that statement (B) need not necessarily be true since II can be a free expansion process. If II allows for heat to flow in and out of the system (so now it is an Isothermal expansion), then (B) is a true statement. How does one resolve such a conflict?