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 28 of 30
- A. Decreases
- B. May increase or decrease, depends on the system
- C. Remains unchanged
- D. Increases
Explanation: A pure liquid boils when its vapour pressure equals the system pressure.
Correct answer: Increases- A. 1
- B. > 1
- C. 0
- D. ∞
Explanation: At an azeotrope, the vapour and liquid have the same composition, so their relative volatility is 1.
Correct answer: 1- A. Methyl ethyl ketone
- B. Water
- C. Carbon dioxide
- D. Carbon tetrachloride
Explanation: Carbon dioxide is the standard supercritical extraction solvent because it has a mild critical temperature, is nonflammable, inexpensive…
Correct answer: Carbon dioxide- A. P vs. log T
- B. log P vs. log T
- C. T vs. P
- D. log P vs. T
Explanation: A Cox chart plots the logarithm of vapour pressure against temperature, commonly using log P versus T.
Correct answer: log P vs. T- A. Endothermic
- B. Exothermic
- C. Not possible
- D. None of these
Explanation: SO3 reacts with concentrated sulfuric acid to form oleum, and this absorption releases substantial heat.
Correct answer: Exothermic- A. Exchange of heat with colder stream
- B. Adiabatic expansion through a throttle valve (Joule-Thomson expansion)
- C. Merely compressing it beyond critical pressure
- D. Adiabatic expansion against a piston or in a turbine
Explanation: Pressure alone cannot liquefy a gas when the temperature is above its critical temperature, even if the pressure exceeds the critical…
Correct answer: Merely compressing it beyond critical pressure- A. Increases
- B. Increases linearly
- C. Decreases
- D. Decreases linearly
Explanation: Oxidation of SO2 to SO3 is exothermic, so increasing temperature shifts equilibrium toward the reactants.
Correct answer: Decreases- A. Less changes in fluidity of oil with temperature
- B. Substantially high change in fluidity of oil with temperature
- C. Its unsuitability under varying temperature conditions
- D. None of these
Explanation: A high viscosity index means the oil's viscosity changes relatively little as temperature changes.
Correct answer: Less changes in fluidity of oil with temperature- A. Merely compression of gas beyond its critical pressure
- B. Adiabatic expansion against a piston or in a turbine
- C. Heat exchange with colder stream
- D. Joule-Thomson expansion cooling
Explanation: The Claude liquefaction process combines heat exchange with expansion in an engine or turbine, producing cooling through nearly adiabatic…
Correct answer: Adiabatic expansion against a piston or in a turbine- A. Inerts
- B. Pressure
- C. Temperature
- D. All A., B. & C.
Explanation: For a given reaction, the thermodynamic equilibrium constant depends only on temperature.
Correct answer: Temperature- A. Low temperature and high pressure
- B. Low temperature and low pressure
- C. High temperature and low pressure
- D. High temperature and high pressure
Explanation: SO2 oxidation to SO3 is exothermic, so lowering temperature favours equilibrium conversion, while the reduction in gas moles makes high…
Correct answer: Low temperature and high pressure- A. Exchange of heat with colder stream
- B. Adiabatic expansion through a throttle valve (Joule-Thomson expansion)
- C. Adiabatic expansion against a piston or in a turbine
- D. Merely compressing the gas beyond its critical pressure
Explanation: The Linde process cools compressed gas by regenerative heat exchange and Joule-Thomson throttling, which is approximately isenthalpic…
Correct answer: Adiabatic expansion through a throttle valve (Joule-Thomson expansion)- A. High pressure & high temperature
- B. Low pressure & high temperature
- C. High pressure & low temperature
- D. Low pressure & low temperature
Explanation: High pressure brings molecules closer together and low temperature reduces their kinetic energy, both favouring condensation.
Correct answer: High pressure & low temperature- A. None of these
- B. H2SO4 and 80kg of SO3
- C. SO3 for each 100 kg of H2SO4
- D. SO3 and 80kg of H2SO4
Explanation: A 20% oleum contains 20 kg of free SO₃ in every 100 kg of oleum, with the remaining 80 kg treated as H₂SO₄ in this convention.
Correct answer: SO3 and 80kg of H2SO4- A. P
- B. √P
- C. P2
- D. 1/P
Explanation: The reaction 2SO₂ + O₂ ⇌ 2SO₃ reduces the total number of gas moles by one, so increasing pressure favours SO₃ formation.
Correct answer: √P- A. Is always less than 1
- B. Is always greater than 1
- C. Depends on the choice of the standard state
- D. Can be 5
Explanation: Gas activity is defined relative to a chosen standard-state fugacity, commonly as a/f° or f/f°.
Correct answer: Depends on the choice of the standard state- A. None of these
- B. Temperature
- C. Volume
- D. Pressure
Explanation: The ideal gas-turbine, or Brayton, cycle consists of compression and expansion at approximately constant pressure during heat addition and…
Correct answer: Pressure- A. Carbon dioxide
- B. Oxygen
- C. Helium
- D. None of these
Explanation: Carbon dioxide can pass directly from vapour to solid as dry ice by deposition, without a liquid phase at pressures below its triple-point…
Correct answer: Carbon dioxide- A. 3171Pa
- B. 3567Pa
- C. 1.01 x 10^5Pa
- D. 5000Pa
Explanation: Using the integrated Clausius–Clapeyron relation, ln(f₂/f₁) = ΔHvap/R(1/T₁ − 1/T₂), raises the fugacity from about 3171 Pa at 298 K to…
Correct answer: 3567Pa- A. Remain same
- B. Increases
- C. Decreases
- D. May increase or decrease
Explanation: The latent heat of vaporisation falls as pressure rises because the saturated-liquid and saturated-vapour states become more alike near…
Correct answer: Decreases