A sealed vertical cylinder fitted with a frictionless, massless piston contains an ideal gas. The cylinder can exchange heat only through its curved sidewall; the top and bottom are perfectly insulated. The system undergoes the following two-step cycle in a laboratory at 300K.
Step 1 (Isothermal Compression): The gas is compressed very slowly until its volume is halved while it remains at 300K. During this step, 1.5kJ of work is done on the gas, and an equal amount of thermal energy leaves the gas through the sidewall to Reservoir A located at 300K.
Step 2 (Adiabatic Expansion): Immediately after Step 1, the sidewall is covered with perfect insulation. The gas then expands rapidly, doing 1.5kJ of work on the piston. No heat is exchanged with any reservoir during this step.
Ignore any changes in kinetic or potential energy of the piston. Answer the following questions about entropy changes.
(a) For Step 1, state the sign (positive, negative, or zero) of the entropy change for (i) the gas, (ii) Reservoir A, and (iii) the universe. Justify each answer qualitatively.
(b) For Step 2, state the sign of the entropy change for (i) the gas, (ii) the surroundings other than the gas (including the piston), and (iii) the universe. Provide justification.
(c) Determine the sign of the net entropy change of the universe for the complete two-step cycle. Discuss whether the overall process is reversible, irreversible, or impossible, supporting your answer with reasoning based on your previous results.