For each of the following processes, state which of ∆U, ∆H, ∆S, ∆Suniv, ∆A, and ∆G must be...

For each of the following processes, state which of ∆U, ∆H, ∆S, ∆Suniv, ∆A, and ∆G must be zero, (a) A nonideal gas undergoes a Carnot cycle, (b) Hydrogen is burned in an adiabatic calorimeter of fixed volume, (c) A nonideal gas undergoes a Joule-Thomson expansion, (d) Ice is melted at 0°C and 1 atm.