Engineering Thermodynamics
The condition for the reversibility of a cycle is

All of these
All the processes, taking place in the cycle of operation, must be extremely slow
The working parts of the engine must be friction free
The pressure and temperature of the working substance must not differ, appreciably, from those of the surroundings at any stage in the process

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Engineering Thermodynamics
Work-done during adiabatic expansion is given by (where p1 v1, T1 = Pressure, volume and temperature for the initial condition of gas, p2, v2, T2 = Corresponding values for the final condition of gas, R = Gas constant, and γ = Ratio of specific heats)

[m R T1/(γ - 1)][1 - (p2, v2 /p1 v1)]
[m R (T1 - T2)] /(γ - 1)
(p1 v1 - p2, v2)/(γ - 1)
All of these

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