1. The problem statement, all variables and given/known data I managed to do part (i) and first part to (ii): 2. Relevant equations U = Q + W 3. The attempt at a solution for the first part: T/Tf = 1/(2 - y) for (ii): W = yVP Given: (3/2)R = Q/(nΔT), Q = (3/2)nR(ΔT) Therefore U = Q + W U = (3/2)nR(ΔT) + yVP But then, isn't U already equal to (3/2)nR(ΔT) since its a monoatomic gas? Then that gives y = 0, so i'm utterly confused. Here's what the answer writes: W = yVP H = (3/2)nR(Tf - T) (does H here mean U?) Does this imply that heat transferred Q, equals to zero? so W = U? But there's no indication that this is an adiabatic process? How can we assume that?