Free Chemical Engineering Thermodynamics MCQs with Answers
598 Chemical Engineering Thermodynamics MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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598 questions · page 11 of 30
- A. RT ln K
- B. -RT ln K
- C. -R ln K
- D. T ln K
Explanation: At equilibrium, the standard Gibbs free-energy change is related to the equilibrium constant by ΔG° = −RT ln K.
Correct answer: -RT ln K- A. Stirling
- B. Brayton
- C. Both B. and C
- D. Rankine
Explanation: The ideal Brayton cycle adds heat at constant pressure in its combustor, and the ideal Rankine cycle adds heat at approximately constant…
Correct answer: Both B. and C203. The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for___________________?
- A. Expansion of a real gas
- B. Cooling of a real gas
- C. Heating of an ideal gas
- D. Reversible isothermal volume change
Explanation: For a reversible isothermal change of an ideal gas, integrating dS = -nR dP/P gives ΔS = -nR ln(P2/P1), equivalently nR ln(V2/V1).
Correct answer: Reversible isothermal volume change- A. Path functions
- B. State functions
- C. Intensive properties
- D. Extensive properties
Explanation: Heat and work depend on the path followed between two states, so they are path functions rather than state functions.
Correct answer: Path functions- A. (atm)Δx, when Δx is negative
- B. (atm)Δx, when Δx is positive
- C. Dimensionless, when Δx = 0
- D. (atm)Δx2, when Δx > 0
Explanation: For gaseous reactions, the pressure dependence of Kp is proportional to (pressure unit)^Δx, where Δx is moles of gaseous products minus…
Correct answer: (atm)Δx2, when Δx > 0- A. Decreases
- B. Decreases exponentially
- C. Remain constant
- D. Increases
Explanation: In a stable homogeneous solution, increasing a component's mole fraction increases its chemical potential and hence its fugacity at fixed…
Correct answer: Increases- A. Freon
- B. Liquid sulphur dioxide
- C. Methyl chloride
- D. Ammonia
Explanation: Large centrifugal refrigeration compressors have historically used Freons such as R-11 and R-12 because of their suitable pressure and…
Correct answer: Freon- A. n = y = 1.4
- B. n = 1
- C. n = 0
- D. n = 1.66
Explanation: For compression between the usual specified inlet and outlet pressures, isothermal compression, n = 1, requires the least work because…
Correct answer: n = 1- A. 2HI ⇌ H2 + I2
- B. 2SO2 + O2 ⇌ 2SO3
- C. N2O4 ⇌ 2NO2
- D. None of these
Explanation: The relation Kp = Kc(RT)^Δn shows that Kp is greater than Kc for the textbook case Δn > 0.
Correct answer: N2O4 ⇌ 2NO2- A. Either B. or C; depends on the type of alloy
- B. Equal to
- C. More than
- D. Less than
Explanation: The total vapour pressure of an alloy or liquid mixture is the sum of the partial pressures of its constituents, so each individual…
Correct answer: Less than- A. Decreases in all spontaneous (or irreversible) processes
- B. Change during a spontaneous process has a negative value
- C. Remains unchanged in reversible processes carried at constant temperature and pressure
- D. All A, B. and C
Explanation: A suitable free energy decreases for an irreversible spontaneous change and remains constant for a reversible change at the relevant fixed…
Correct answer: All A, B. and C- A. 0
- B. 1
- C. 2
- D. 3
Explanation: The phase rule is F = C − P + 2. For a one-component triple point, C = 1 and P = 3, giving F = 0, so temperature and pressure are fixed.
Correct answer: 0- A. Ordinary vapour compression cycle
- B. Carnot cycle
- C. Air cycle
- D. Vapour compression with a reversible expansion engine
Explanation: The Carnot refrigerator has the maximum possible COP, while reversible expansion improves vapour-cycle performance.
Correct answer: Air cycle214. With increase in temperature, the atomic heat capacities of all solid elements_________________?
- A. Decreases linearly
- B. Decreases
- C. Remains unchanged
- D. Increases
Explanation: The heat capacity of a solid generally rises with temperature as additional lattice vibrational modes become excited, approaching the…
Correct answer: Increases- A. Pressure and temperature
- B. Number of intermediate chemical reactions involved
- C. State of combination and aggregation in the beginning and at the end of the reaction
- D. None of these
Explanation: Enthalpy is a state function, so the overall enthalpy change depends only on the initial and final states, not on how many intermediate…
Correct answer: Number of intermediate chemical reactions involved- A. O2
- B. N2
- C. He
- D. H2
Explanation: Helium has extremely weak intermolecular attractions and therefore shows very small departures from ideal-gas behaviour under ordinary…
Correct answer: He217. For a multi-component system, the term chemical potential is equivalent to the ___________________?
- A. Molal concentration difference
- B. Molar free energy
- C. Molar free energy change
- D. Partial molar free energy
Explanation: Chemical potential is defined as the partial molar Gibbs free energy, mu_i = (partial G/partial n_i) at constant temperature, pressure…
Correct answer: Partial molar free energy- A. Carnot refrigeration cycle
- B. Air refrigeration cycle
- C. Vapor compression cycle using expansion engine
- D. Vapor compression cycle using expansion valve
Explanation: For fixed evaporator and condenser temperatures, the Carnot refrigerator has the maximum possible COP because it is fully reversible.
Correct answer: Carnot refrigeration cycle- A. Mole fraction
- B. Pressure
- C. Activity
- D. Activity co-efficient
Explanation: The fugacity coefficient is defined as phi = f/P, so it compares a real substance's fugacity with its pressure.
Correct answer: Pressure- A. Not changed
- B. Increasing
- C. Decreasing
- D. Data sufficient, can't be predicted
Explanation: Increasing entropy generation destroys available work, or exergy, when the heat-engine system and surroundings are considered under…
Correct answer: Decreasing