An ideal gas undergoes a reversible isothermal expansion from state I to state II followed by a reversible adiabatic expansion from state II to state III . The correct plot s representing the changes from state I to state III is(are) ( p : pressure, V : volume, T : temperature, H : enthalpy, S : entropy)

Step-by-step solution

Reversible isothermal expansion from I → II during this process T = constant ΔH = ΔU = 0 H = constant. ΔS ≠ 0 Entropy will increase PV = constant. and during adiabatic reversible expansion. q = 0 ΔU = w = − ve so T will decrease ΔH = nc p ΔT = - ve H will decrease ΔS = 0 (isoentropic process) S = constant. and pv r = constant. Keeping in mind correct graph are 1,2 and 4.