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One mole of an ideal gas with Cv,m=5/2R undergoes the transformation described in the following list from an initial state described by T=250K and P=1.00 bar. q,w,U,H and S for each process. a) The gas undergoes a reversible adiabatic expansion until the final pressure is half its initial value. b) The gas undergoes an adiabatic expansion against a constant external pressure of 0.500 bar until the final pressure is half its value. c) The gas undergoes an expansion against a constant external pressure of zero bar until the final pressure is equal half of its initial value