All Free Chemical Engineering MCQs with Answers
Every Chemical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
6,983 questions · page 291 of 350
- A. Diffusion co-efficient
- B. None of these
- C. NTU
- D. Mass transfer co-efficient
Explanation: A wetted wall column provides a controlled contact area and is commonly used to determine gas-side or liquid-side mass-transfer…
Correct answer: Mass transfer co-efficient- A. Wetted wall
- B. Packed
- C. Bubble cap plate
- D. Spray
Explanation: In a wetted-wall column, the interfacial area is defined geometrically by the wetted wall, making it easier to measure accurately than the…
Correct answer: Wetted wall- A. Increased relative volatility
- B. Thermal decomposition of bottoms
- C. Erosion of the tower
- D. Very efficient operation
Explanation: High pressure raises the boiling temperature of the bottoms liquid, increasing its exposure to severe thermal conditions.
Correct answer: Thermal decomposition of bottoms- A. Large surface per unit volume
- B. Large free cross-section
- C. Low weight per unit volume
- D. Large weight of liquid retained
Explanation: A good packing should retain little liquid because excessive holdup increases pressure drop, inventory, and operating cost.
Correct answer: Large weight of liquid retained- A. Lewis relationship
- B. Galileo number
- C. Weber number
- D. Dean number
Explanation: The Lewis relationship connects heat and mass transfer in gas-liquid contact and is fundamental to psychrometric calculations.
Correct answer: Lewis relationship- A. 1
- B. ∞
- C. 0
- D. None of these
Explanation: At the boiling point, the saturation vapour pressure equals the total pressure, so the denominator in the saturation-humidity expression…
Correct answer: ∞- A. Caustic solution
- B. Dilute HCl
- C. Dilute ammoniacal liquor
- D. Ethanolamine
Explanation: Ammonia is a basic, highly water-soluble component of coke-oven gas and is absorbed in dilute ammoniacal liquor during scrubbing.
Correct answer: Dilute ammoniacal liquor- A. No change in theoretical
- B. None of these
- C. Major decrease in the number of
- D. Marginal decrease in the number of
Explanation: Ethanol-water separation becomes increasingly difficult near the azeotropic composition, so reducing the distillate specification from 95%…
Correct answer: Marginal decrease in the number of- A. Porosity
- B. Durability
- C. Size
- D. Cost
Explanation: High porosity provides more open passage for gas flow, reducing pressure drop and delaying flooding while allowing liquid to contact the…
Correct answer: Porosity- A. Time of contact between the two phases should be less
- B. Interfacial surface between liquid and gas phase should be large
- C. Gas velocity should be very low
- D. Liquid entrainment should be severe
Explanation: Tray efficiency improves when the interfacial area between gas and liquid is large, because mass transfer then has more area to occur.
Correct answer: Interfacial surface between liquid and gas phase should be large- A. Liquid stream should be distributed uniformly
- B. Gas stream should be distributed uniformly
- C. Both gas as well as liquid streams should be distributed uniformly
- D. By passing should be completely avoided
- E. Answer: Option C
Explanation: Uniform distribution of both gas and liquid prevents dry zones, channeling, and bypassing, so the entire column cross-section contributes…
Correct answer: Both gas as well as liquid streams should be distributed uniformly- A. Binary mixture is represented by the apex
- B. Binary mixture is represented by any point inside
- C. Ternary mixture is represented by the sides
- D. Pure component is represented by the apex
Explanation: In an equilateral ternary diagram, each apex represents a pure component, each side represents a binary mixture, and interior points…
Correct answer: Pure component is represented by the apex- A. Pachuca tanks
- B. Centrifugal extractor
- C. Bollman extractor
- D. None of these
Explanation: Pachuca tanks are agitated vessels commonly used for leaching ores, including uranium and gold ores.
Correct answer: Pachuca tanks- A. Equal to the heat of formation of surface compound
- B. Equal to the heat of wetting
- C. Zero
- D. Called integral heat of adsorption
Explanation: For physical adsorption, the adsorption heat exceeds the condensation heat because adsorption also includes the heat released when the…
Correct answer: Equal to the heat of wetting- A. Percentage
- B. Relative
- C. Molal
- D. None of these
Explanation: Standard humidity charts plot humidity ratio or molal humidity against dry-bulb temperature, so the ordinate gives the amount of water…
Correct answer: Molal- A. Of slope = 1
- B. Of slope = 0.1
- C. None of these
- D. Tangential to the equilibrium curve
Explanation: At the minimum liquid rate, the operating line just touches the equilibrium curve, creating a pinch point and requiring an infinitely…
Correct answer: Tangential to the equilibrium curve5817. Separation of two volatile liquids by distillation makes use of their________________________?
- A. Relative volatility
- B. Selectivity
- C. Solubility
- D. Density difference
Explanation: Distillation separates volatile liquids because the more volatile component preferentially enters the vapour phase.
Correct answer: Relative volatility- A. End of falling
- B. Beginning of constant
- C. Beginning of falling
- D. None of these
Explanation: At the critical moisture content, the constant-rate period ends and the falling-rate period begins.
Correct answer: Beginning of falling- A. √T
- B. T
- C. T3
- D. T2
Explanation: In a diffusion-controlled falling-rate period, the drying time follows the characteristic diffusion time, which varies as length squared.
Correct answer: T2- A. Temperature
- B. Composition
- C. Total pressure
- D. All A., B. and C.
Explanation: Dew point is determined by vapour composition and total pressure, not by the mixture's present temperature.
Correct answer: Temperature