Which of the following is true for an ideal gas undergoing an irreversible adiabatic expansion against constant external
For an irreversible adiabatic expansion (q = 0), Δ U = w = -Pext Δ V. Since Δ V > 0, w < 0, and thus Δ U < 0.
Ref: NCERT Class 11 Chemistry > Chapter 5: Thermodynamics > Topic: Heat Capacity and Calorimetry and Measurement of Enthalpy