The GATE Grind

GATE 2026 MT – Question 30

Metallurgical Thermodynamics · Thermodynamic laws and functions · 1 mark · Multiple select

Choose the correct option(s). Here ‘A’ is the Helmholtz free energy and ‘G’ is the Gibbs free energy.

  1. ‘A’ provides a criterion for equilibrium in a system with constant temperature and constant pressure
  2. ‘G’ provides a criterion for equilibrium in a system with constant temperature and constant pressure
  3. ‘A’ provides a criterion for equilibrium in a system with constant temperature and constant volume
  4. ‘G’ provides a criterion for equilibrium in a system with constant temperature and constant volume

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (B) ‘G’ provides a criterion for equilibrium in a system with constant temperature and constant pressure; (C) ‘A’ provides a criterion for equilibrium in a system with constant temperature and constant volume

Explanation

At fixed temperature and pressure, spontaneous change lowers Gibbs free energy and equilibrium minimizes G. At fixed temperature and volume, Helmholtz free energy A is minimized instead. Thus **B,C** correctly pair each potential with its natural controlled variables; the reversed pairings do not give the appropriate general criterion.