Thermodynamics MCQs Archives

391. Pick out the wrong statement pertaining to the decomposition of PCl5 represented by, PCl5 ⇋ PCl3 + Cl₂.Degree of dissociation of PCl5 will

A. Decrease on addition of Cl₂

B. Increase on addition of an inert gas at constant pressure

C. Decrease on increasing the pressure of the system

D. None of these

✅ The correct answer is option D.

392. If the internal energy of an ideal gas decreases by the same amount as the work done by the system, then the

A. Process must be isobaric

B. Temperature must decrease

C. Process must be adiabatic

D. Both B and C

✅ The correct answer is option D.

393. Equilibrium constant of a reaction varies with the

A. Initial concentration of the reactant

B. Pressure

C. Temperature

D. None of these

✅ The correct answer is option C.

394. “The fugacity of a gas in a mixture is equal to the product of its mole fraction and its fugacity in the pure state at the total pressure of the mixture”. This is

A. The statement as per Gibbs-Helmholtz

B. Called Lewis-Randall rule

C. Henry’s law

D. None of these

✅ The correct answer is option B.

395. Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the __________ equation.

A. Gibbs-Duhem

B. Maxwell’s

C. Clayperon

D. None of these

✅ The correct answer is option C.

396. While dissolving a gas into a liquid at a constant temperature, the ratio of the concentration of the gas in the solution phase and in the gaseous phase is

A. Infinity

B. Unity

C. Constant

D. Negative

✅ The correct answer is option C.

397. Standard temperature and pressure (S.T.P.) is

A. 0°C and 750 mm Hg

B. 15°C and 750 mm Hg

C. 0°C and 1 kgf/cm²

D. 15°C and 1 kgf/cm²

✅ The correct answer is option A.

398. As the entropy of the universe is increasing, day by day, the work producing capacity of a heat engine is

A. Not changed

B. Decreasing

C. Increasing

D. Data sufficient, can’t be predicted

✅ The correct answer is option B.

399. In the equation, PVn = constant, if the value of n = ± ∞, then it represents a reversible __________ process.

A. Adiabatic

B. Isometric

C. Isentropic

D. Isothermal

✅ The correct answer is option B.

400. A large iceberg melts at the base, but not at the top, because of the reason that

A. Ice at the base contains impurities which lowers its melting point

B. Due to the high pressure at the base, its melting point reduces

C. The iceberg remains in a warmer condition at the base

D. All of the above

✅ The correct answer is option B.