The curve represents an adiabatic reversible process for an

The curve represents an adiabatic reversible process for an ideal gas. Which regions would be reached by an adiabatic irreversible process?

Solution

Clearly,region B (red shaded region),will be reached by an irreversible process.

Because the region below the curve (say in P-V diagram) will always represent the adiabatic reversible process for an ideal gas.