181. Melting of wax is accompanied with __________ in entropy.
A. Increase
B. Decrease
C. No change
D. None of these
✅ The correct answer is option A.
Thermodynamics MCQs
182. Which of the following is true for Virial equation of state?
A. Virial co-efficients are universal constants
B. Virial co-efficients
C. Virial co-efficients are function of temperature only
D. For some gases, Virial equations and ideal gas equations are the same
✅ The correct answer is option C.
183. Domestic refrigerator usually works on the __________ refrigeration cycle.
A. Carnot
B. Air
C. Absorption
D. Vapour-ejection
✅ The correct answer is option C.
184. In the decomposition of PCl5 represented by, PCl5 ⇋ PCl3 + Cl₂, decrease in the pressure of the system will __________ the degree of dissociation of PCl5.
A. Increase
B. Decrease
C. Not alter
D. None of these
✅ The correct answer is option A.
185. __________ law of thermodynamics ascertains the direction of a particular spontaneous process.
A. Zeroth
B. First
C. Second
D. Third
✅ The correct answer is option C.
186. Which of the following processes can not be made reversible even under ideal condition of operation?
A. Free expansion of a gas
B. Compression of air in a compressor
C. Expansion of steam in a turbine
D. All of the above
✅ The correct answer is option A.
187. A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system
A. Its internal energy (U) decreases and its entropy (S) increases
B. U and S both decreases
C. U decreases but S is constant
D. U is constant but S decreases
✅ The correct answer is option B.
188. Claussius-Clayperon equation gives accurate result, when the
A. Vapour pressure is relatively low and the temperature does not vary over wide limits
B. Vapour obeys the ideal gas law and the latent heat of vaporisation is constant
C. Volume in the liquid state is negligible compared with that in the vapour state
D. All of the above
✅ The correct answer is option D.
189. The expression, nRT In P₁/P₂ , is for the____of an ideal gas.
A. Compressibility
B. Work done under adiabatic contition
C. Work done under isothermal condition
D. Co-efficient of thermal expansion
✅ The correct answer is option C.
190. If we increase the pressure on a substance (which is at its triple point), then the triple point
A. Increases
B. Decreases
C. Remains unchanged
D. May increase or decrease ; depends on the substance
✅ The correct answer is option C.