The correct options are
A The work done on the gas is maximum when it is compressed irreversibly from
(p2,V2) to
(p1,V1) against constant pressure
p1.
B The work done by the gas is less when it is expanded reversibly from
V1 to
V2 under adiabatic conditions as compared to that when expanded reversibly from
V1 to
V2 under isothermal conditions.
C If the expansion is carried out freely, it is simultaneously both is isothermal as well as adiabatic.
(A)
ω=−PextΔVWork done on gas when compressed
ω= is positive
∴ equation becomes
ω=PextΔV
(B) under adiabatic conditions
ω=(P2V2−P1V1)(γ−1)
since equation V2>V1
∴ω=+ve (work done on system)
for reversibly condition (Isothermal)
ω=−nRTlnV2V1
=V2>V1
ω=−ve (work done on system)
ω=−ve (for adiabatic reversibly work done by gas)
ω=+ve (for isothermal reversibly work done by gas)
(C) As free expansion in there (irreserible)
∴Pext=0
ω=(−Pext×ΔV)=0 (Isothermal irreversible process)
In adiabatic ΔU=−ve
ΔU=q+ω
−=0+ω
ω=−negative
similarly, ΔG=ΔH−TΔs
gas expand ∴Δs=+ve
ΔG=ΔH−Ve
=ΔV+pΔV−ve
=q+w+pΔc−ve
=o+w+w−ve
=−ve+(−ve)−ve
ΔG=−ve
∴ It is spontaneous process
∴ both take place simultaneously