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 13 of 30
- A. Adiabatic
- B. Isentropic
- C. Isometric
- D. Isothermal
Explanation: As n approaches positive or negative infinity in PV^n = constant, any finite pressure change requires the volume change to approach zero.
Correct answer: Isometric- A. Unity at all pressures
- B. Inversely proportional to pressure
- C. Directly proportional to pressure
- D. None of these
Explanation: An ideal gas has no intermolecular interactions and obeys the ideal-gas reference behaviour, so its activity coefficient is unity.
Correct answer: Unity at all pressures- A. 448
- B. 224
- C. 22.4
- D. Data insufficient; can't be computed
Explanation: Liquid oxygen has approximately 32 g/mol, so 640 g represents 20 mol. At STP, each mole occupies 22.4 L, giving 20 × 22.4 = 448 L.
Correct answer: 448- A. Decrease
- B. Increase
- C. Not alter
- D. None of these
Explanation: The reaction produces two moles of gas from one mole, so lowering pressure shifts equilibrium toward the side with more gas molecules.
Correct answer: Increase- A. CO2
- B. O2
- C. H2
- D. N2
Explanation: Hydrogen has a very low inversion temperature, so at ordinary atmospheric conditions throttling produces heating rather than cooling.
Correct answer: H2246. Compressibility factor-reduced pressure plot on reduced co-ordinates facilitates__________________?
- A. More accurate plotting
- B. Covering of wide range
- C. Easier plotting
- D. Use of only one graph for all gases
Explanation: Reduced pressure and temperature make gases follow a generalized compressibility relationship, allowing one compressibility chart to…
Correct answer: Use of only one graph for all gases- A. μ° + RT ln f
- B. μ°+ R ln f
- C. μ° + T ln f
- D. μ° + R/T ln f
Explanation: For a real gas, fugacity replaces pressure in the chemical-potential expression: μ = μ° + RT ln(f/f°).
Correct answer: μ° + RT ln f- A. V ∝ 1/P
- B. V ∝ 1/T
- C. V/T = Constant
- D. PV/T = Constant
Explanation: Charles' law states that gas volume is directly proportional to absolute temperature at constant pressure.
Correct answer: V/T = Constant- A. Lewis-Randall
- B. Margules
- C. Van Laar
- D. Both B. & C.
Explanation: The Margules and Van Laar equations are activity-coefficient models whose parameters are fitted to experimental vapor-liquid-equilibrium…
Correct answer: Both B. & C.- A. -RT ln 0.5
- B. -2 RT ln 0.5
- C. 0.5 RT
- D. 2 RT
Explanation: The minimum reversible separation work for an ideal mixture is −RTΣxi ln xi.
Correct answer: -RT ln 0.5- A. 72
- B. 92
- C. 142
- D. 192
Explanation: Trouton's rule gives the molar entropy of vaporisation at the normal boiling point as approximately 85 to 90 J/(mol·K) for many liquids.
Correct answer: 92252. 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. The iceberg remains in a warmer condition at the base
- C. Due to the high pressure at the base, its melting point reduces
- D. All A, B. and C
Explanation: Pressure at the base lowers the melting point of ice because ice occupies more volume than liquid water.
Correct answer: Due to the high pressure at the base, its melting point reduces- A. Vapor pressure
- B. None of these
- C. Chemical potential
- D. Partial pressure
Explanation: For an ideal-gas mixture, the fugacity of component i equals its partial pressure, fᵢ = yᵢP.
Correct answer: Partial pressure- A. Both A. and B
- B. Free energy, entropy and enthalpy
- C. Volume, mass and number of moles
- D. None of these
Explanation: Extensive properties depend on the amount of material and are additive, so volume, mass, moles, free energy, entropy, and enthalpy all…
Correct answer: Both A. and B- A. Azeotropic mixture only
- B. Ternary solutions
- C. Binary solutions
- D. None of these
Explanation: The Van Laar equations are primarily used to correlate activity coefficients in binary liquid mixtures.
Correct answer: Binary solutions- A. Molar heat capacity
- B. None of these
- C. Viscosity
- D. Internal energy
Explanation: Internal energy is an extensive property because it increases with the amount of substance present.
Correct answer: Internal energy- A. Internal energy
- B. Enthalpy
- C. Either A. or B
- D. Neither A. nor B
Explanation: At constant volume, boundary work is zero, so the heat supplied equals the change in internal energy, qᵥ = ΔU, assuming only…
Correct answer: Internal energy- A. High pressure & low temperature
- B. Low pressure & high temperature
- C. Low pressure & low temperature
- D. None of these
Explanation: Real gases approach ideal-gas behaviour when intermolecular forces and molecular volume become negligible, which occurs at low pressure…
Correct answer: Low pressure & high temperature- A. ΔF = ΔH + T [∂(ΔF)/∂T]P
- B. ΔF = ΔH - TΔT
- C. d(E - TS) T, V < 0
- D. dP/dT = ΔHvap/T.ΔVvap
Explanation: The Gibbs-Helmholtz relation can be written as ΔG = ΔH + T[∂(ΔG)/∂T]ₚ; the option uses F for the free-energy function.
Correct answer: ΔF = ΔH + T [∂(ΔF)/∂T]P- A. Concentration of the constituents only
- B. Quantities of the constituents only
- C. Temperature only
- D. All A, B. and C
Explanation: For a mixture, the Gibbs free-energy change of mixing depends on composition or concentrations, the amounts mixed, and temperature through…
Correct answer: All A, B. and C