1. The problem statement, all variables and given/known data for number 3,4,5 i'm still trying 2. Relevant equations PV/T = PV/T q = ΔU + W W = P ΔV 3. The attempt at a solution (3) I used PV/T = PV/T to find the ΔT for each process for A→B I find PV/TA = P3V/TB ----- TB = 3TA (T increase) for B→C I find P3V/TB = 4P3V/TC ----- TC = 4TB (T increase) for C→D I find 4P3V/TC = 4PV/TD ----- TD = ⅓TC (T decrease) for D→A I find 4PV/TD = PV/TA ----- TA = ¼TD (T decrease) so I drew a conclusion that among 4 process , gas received from outside max at process B→C are the answer and the reason right? (4) at process B→C there's no ΔV. So, W = 0 q = ΔU + 0 q = the amount of heat added or removed from system So, the question for (4) Is to find q at process B→C ? q for monoatomic gas is 3/2nKT but what's the n (mol) known? can you give me some clue to answer (4)? (5) now the heat that gas emits, I thought there are 2 W : W at A→B = P.(3V - V) = 2PV W at C→D = 4P(V-3V) = -8PV (minus ?) can you give me some clue to answer (5)?