431. Gibbs free energy at constant pressure and temperature under equilibrium conditions is
A. ∞
B. 0
C. Maximum
D. Minimum
✅ The correct answer is option D.
Thermodynamics MCQs
432. Any substance above its critical temperature exists as
A. Saturated vapour
B. Solid
C. Gas
D. Liquid
✅ The correct answer is option C.
433. Helmholtz free energy (A) is defined as
A. A = H – TS
B. A = E – TS
C. A = H + TS
D. None of these
✅ The correct answer is option B.
434. At __________ point, all the three phases (i.e.solid, liquid and gas) co-exist.
A. Eutcetic
B. Triple
C. Plait
D. Critical
✅ The correct answer is option B.
435. Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is
A. 1
B. 4
C. 2
D. 3
✅ The correct answer is option C.
436. Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will
A. Increase
B. Decrease
C. Remain unchanged
D. First fall and then rise
✅ The correct answer is option A.
437. For a real gas, the chemical potential is given by
A. RT dlnP
B. RT dlnf
C. R dlnf
D. None of these
✅ The correct answer is option B.
438. Which of the following will increase the volume of a real gas by four times ?
A. Doubling the absolute temperature as well as pressure of the gas
B. Reducing pressure to one fourth at constant temperature
C. Reducing temperature to one fourth at constant pressure
D. Reducing the temperature to half and doubling the pressure
✅ The correct answer is option B.
439. Van Laar equation deals with the activity co-efficients in
A. Binary solutions
B. Ternary solutions
C. Azeotropic mixture only
D. None of these
✅ The correct answer is option A.
440. What is the value of ln y (where y = activity co-efficient) for ideal gases?
A. Zero
B. Unity
C. Infinity
D. Negative
✅ The correct answer is option A.