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 283 of 350
- A. Low pressure drop
- B. High pressure drop
- C. Low velocity of the liquid
- D. High temperature
Explanation: Flooding occurs when the gas or vapour velocity becomes so high that it entrains liquid and prevents proper downward flow, producing a…
Correct answer: High pressure drop- A. Gilliland
- B. Stefan
- C. Toor and Marcello
- D. Fick
Explanation: The film-penetration model combines the ideas of a stagnant interfacial film and penetration by fluid elements, and is associated with…
Correct answer: Toor and Marcello- A. Stanton
- B. Sherwood
- C. None of these
- D. Peclet
Explanation: The product of Reynolds and Schmidt numbers is the mass-transfer Peclet number, \(Pe=Re\,Sc\), which compares convective transport with…
Correct answer: Peclet- A. Increases
- B. Decreases
- C. Remain same
- D. May increase or decrease; depends on system
Explanation: During constant-reflux batch distillation, the more volatile component is removed preferentially, so its concentration in the still…
Correct answer: Decreases- A. Decoction
- B. Percolation
- C. Elutriation or elution
- D. None of these
Explanation: When the soluble material is concentrated on the surface of an insoluble solid, the solvent mainly washes it away rather than dissolving…
Correct answer: Elutriation or elution5646. The recovery of penicillin from the acidified fermentation broth is done by__________________?
- A. Distillation
- B. Evaporation
- C. Absorption
- D. Liquid extraction
Explanation: Acidification converts penicillin into a form that preferentially partitions into an immiscible organic solvent, so liquid-liquid…
Correct answer: Liquid extraction- A. > 1
- B. 1
- C. < 1
- D. ≤ 1
Explanation: The absorption factor must exceed unity for the specified absorption to be feasible with a finite number of stages.
Correct answer: > 1- A. Liquid-solid
- B. Fluid-solid
- C. Gas-solid
- D. Solid-solid
Explanation: Adsorption occurs when a solute from a fluid phase accumulates on a solid surface, so it is generally classified as a fluid-solid…
Correct answer: Fluid-solid- A. Avoiding deposition on cooler surfaces
- B. Formation of nuclei
- C. Crystal growth
- D. All A., B. and C.
Explanation: Agitation keeps crystals suspended, improves heat and mass transfer, reduces deposition on cooled surfaces, and promotes controlled…
Correct answer: All A., B. and C.- A. Thermal diffusivity to mass diffusivity
- B. Mass diffusivity to momentum diffusivity
- C. Momentum diffusivity to thermal diffusivity
- D. None of these
Explanation: The Lewis number compares thermal diffusivity with mass diffusivity: Le = α/D.
Correct answer: Thermal diffusivity to mass diffusivity- A. Sherwood
- B. Schmidt
- C. Peclet
- D. Stanton
Explanation: The Sherwood number, Sh = kL/D, compares convective mass transfer with molecular diffusion.
Correct answer: Sherwood- A. Evaporator
- B. Distillation column
- C. Dryer
- D. Crystalliser
Explanation: A Cox chart gives vapour-pressure or boiling-point relationships for components and is used in estimating relative volatility for…
Correct answer: Distillation column- A. √T and T3/2
- B. T and T3/2
- C. T3/2 and T
- D. T3/2 and √T
Explanation: Gas-phase binary diffusivity increases approximately as T raised to the 3/2 power at fixed pressure, while liquid diffusivity is commonly…
Correct answer: T3/2 and T- A. At ambient temperature
- B. None of these
- C. In its vapor form
- D. At its boiling point
Explanation: Decoction is extraction using a solvent heated to its boiling point, commonly used to withdraw soluble constituents from solid materials.
Correct answer: At its boiling point- A. Pressure
- B. Concentration
- C. Thermal
- D. Forced
Explanation: Ordinary diffusion is caused by a concentration gradient, so it is also called concentration diffusion.
Correct answer: Concentration- A. Perforated tray
- B. Bubble cap
- C. Wetted wall
- D. Packed
Explanation: A wetted-wall tower has only a thin liquid film and no trays, packing, or bubbling resistance, so its gas-side pressure drop is the lowest…
Correct answer: Wetted wall- A. Selectivity
- B. Distribution co-efficient
- C. Both A. and B.
- D. Neither A. nor B.
Explanation: A useful extraction solvent should have high selectivity and a favourable distribution coefficient, not values below one.
Correct answer: Neither A. nor B.- A. Agitated vessels
- B. Packed towers
- C. Venturi scrubbers
- D. Wetted wall towers
Explanation: Agitated vessels are conventionally classified mainly as gas-dispersion or mechanically mixed contactors, whereas wetted-wall, packed, and…
Correct answer: Agitated vessels- A. Thermal diffusivity
- B. Mass transfer co-efficient
- C. Kinematic viscosity
- D. Volumetric diffusivity
Explanation: The diffusion coefficient has units of m²/s, like thermal diffusivity, kinematic viscosity, and volumetric diffusivity.
Correct answer: Mass transfer co-efficient- A. > 1 and ≈ 1
- B. 1 and 0
- C. < 1 and ≈ 1
- D. 0 and ≈ 1
Explanation: For air, the Schmidt number is approximately 0.7, hence less than one, while the Lewis number is close to unity because mass and thermal…
Correct answer: < 1 and ≈ 1