One mole of an ideal monatomic perfect gas at 10 atm and 200 K is to be transformed to 0.15 atm and 900 K. Calculate AS, AS2, and the total entropy change for the system which occurs along each of the following two-step reversible paths: a. Isobaric expansion and isochoric temperature drop. b. Isobaric expansion and adiabatic temperature drop. c. Isothermal expansion and isochoric temperature increase. d. Isothermal expansion and isobaric temperature increase.