One mole of an ideal gas is initially at 400K and occupies a volume V0. The gas undergoes the following two-step reversible process:
• Step A: It isothermally compressed at 400K until its volume becomes 2V0.
• Step B: It is then placed in contact with a 300K reservoir and allowed to expand isothermally and reversibly back to the original volume V0.
(i) For Step A, calculate the heat exchanged with the surroundings and the corresponding change in entropy of the gas.
(ii) For Step B, calculate the heat exchanged with the surroundings and the change in entropy of the gas.
(iii) Determine the net entropy change of (a) the gas, (b) the surroundings, and (c) the universe for the entire two-step process.
(iv) Comment on whether the overall two-step process is reversible or irreversible, giving reasons based on your answer to part (iii).