One mole of an ideal gas initially at 400 K and 1.00 atm is subjected to the following cyclic sequence:
1. Isothermal expansion at 400 K from 1.00 atm to 0.25 atm.
2. Cooling at constant volume from 400 K to 200 K.
3. Isothermal compression at 200 K back to 1.00 atm.
4. Heating at constant pressure from 200 K to 400 K.
Which of the following best describes the signs of the entropy changes for the gas in each step and for the complete cycle?
(Signs are listed as Step 1 / Step 2 / Step 3 / Step 4 / Overall)
a) +,0,−,+,+
b) −,−,+,+,0
c) +,−,−,+,0
d) +,−,+,−,0