381. Dry ice is
A. Moisture free ice
B. Solid helium
C. Solid carbon dioxide
D. None of these
✅ The correct answer is option C.
Thermodynamics MCQs
382. Refrigeration cycle
A. Violates second law of thermodynamics
B. Involves transfer of heat from low temperature to high temperature
C. Both A and B
D. Neither A nor B
✅ The correct answer is option B.
383. A gas has a volume of 27.3 c.c. at 0°C. Its volume at 10°C (if pressure remains unchanged) will be __________ c.c.
A. 2.73
B. 28.3
C. 273
D. 283
✅ The correct answer is option B.
384. y = specific heat ratio of an ideal gas is equal to
A. Cp/Cv
B. Cp/(CP-R)
C. 1 + (R/CV)
D. All of the above
✅ The correct answer is option D.
385. Equilibrium constant decreases as the temperature
A. Increases, for an exothermic reaction
B. Decreases, for an exothermic reaction
C. Increases, for an endothermic reaction
D. None of these
✅ The correct answer is option A.
386. The expression for entropy change given by, ΔS = – nR ln (P₂/P₁), holds good for
A. Expansion of a real gas
B. Reversible isothermal volume change
C. Heating of an ideal gas
D. Cooling of a real gas
✅ The correct answer is option B.
387. Gibbs free energy of mixing at constant pressure and temperature is always
A. 0
B. ∞
C. + ve
D. – ve
✅ The correct answer is option D.
388. An isentropic process is carried out at constant
A. Volume
B. Pressure
C. Temperature
D. All of the above
✅ The correct answer is option A.
389. If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.
A. 100
B. 50
C. 205
D. 200
✅ The correct answer is option D.
390. __________ increases with increase in pressure.
A. The melting point of wax
B. The boiling point of a liquid
C. Both A and B
D. Neither A nor B
✅ The correct answer is option C.