351. Mollier diagram is a plot of
A. Temperature vs. enthalpy
B. Temperature vs. enthalpy
C. Entropy vs. enthalpy
D. Temperature vs. internal energy
✅ The correct answer is option C.
Thermodynamics MCQs
352. The expression, ΔG = nRT .In P₂/P₁ , gives the free energy change
A. With pressure changes at constant temperature
B. Under reversible isothermal volume change
C. During heating of an ideal gas
D. During cooling of an ideal gas
✅ The correct answer is option A.
353. The following heat engine produces power of 100000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is
A. 100, 000 kW
B. 160, 000 kW
C. 200, 000 kW
D. 320, 000 kW
✅ The correct answer is option D.
354. Heat requirement for decomposition of a compound into its elements is __________ that is evolved during the formation of that compound from its elements.
A. The same
B. Less than
C. Greater than
D. Different than
✅ The correct answer is option A.
355. Critical compressibility factor for all substances
A. Are more or less constant (vary from 0.2 to 0.3)
B. Vary as square of the absolute temperature
C. Vary as square of the absolute pressure
D. None of these
✅ The correct answer is option A.
356. The internal energy of an ideal gas does not change in a reversible __________ process.
A. Isothermal
B. Adiabatic
C. Isobaric
D. Isometric
✅ The correct answer is option A.
357. If two pure liquid constituents are mixed in any proportion to give an ideal solution, there is no change in
A. Volume
B. Enthalpy
C. Both A & B
D. Neither A nor B
✅ The correct answer is option C.
358. A cylinder contains 640 gm of liquid oxygen. The volume occupied (in litres) by the oxygen, when it is released and brought to standard conditions (0°C, 760 mm Hg) will be __________ litres.
A. 448
B. 224
C. 22.4
D. Data insufficient; can’t be computed
✅ The correct answer is option A.
359. The root mean square speed of molecules of a gas is equal to (where, m = mass of the molecule K = Boltzman’s constant, T = absolute temperature)
A. √(2KT/m)
B. √(3KT/m)
C. √(6KT/m)
D. 3KT/m
✅ The correct answer is option B.
360. All gases during throttling process at atmospheric temperature and pressure show a cooling effect except
A. CO₂
B. H₂
C. O₂
D. N₂
✅ The correct answer is option B.