Free Mass Transfer Operations MCQs with Answers
669 Mass Transfer Operations 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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669 questions · page 9 of 34
- A. 5
- B. 15
- C. 40
- D. 60
Explanation: Wax sweating works best when the oil content is not excessive, because retained oil interferes with separation during controlled heating.
Correct answer: 40- A. Perforated plate
- B. Packed bed
- C. Fluidised bed
- D. Bubble-cap
Explanation: Bubble-cap trays provide good vapour-liquid contact and tolerate changes in liquid and vapour rates, making them a traditional choice for…
Correct answer: Bubble-cap- A. 30-80
- B. 5-10
- C. 150-250
- D. 350-400
Explanation: Vacuum crude distillation commonly operates at about 30–80 mm Hg absolute to lower boiling temperatures and prevent thermal cracking of…
Correct answer: 30-80- A. Pressure
- B. Both A. & B.
- C. Temperature
- D. Neither A. nor B.
Explanation: Knudsen diffusivity varies approximately with the square root of absolute temperature because molecular velocities increase with…
Correct answer: Temperature- A. Measures the catalyst surface area directly
- B. Operates at very high pressure
- C. Is made entirely of stainless steel
- D. None of these
Explanation: BET apparatus determines specific surface area from gas adsorption data, rather than measuring the area directly.
Correct answer: None of these- A. Both A. and B.
- B. Liquid hold-up
- C. Specific inter-facial area
- D. None of these
Explanation: Gas-liquid reactor performance depends strongly on the interfacial area available for transfer and on liquid hold-up, which determines…
Correct answer: Both A. and B.- A. Langmuir adsorption isotherm
- B. Adsorption isobar
- C. Freundlich adsorption isotherm
- D. None of these
Explanation: An adsorption isobar shows the amount adsorbed as temperature changes at constant pressure.
Correct answer: Adsorption isobar- A. Increases
- B. Decreases
- C. Remains unchanged
- D. Increases exponentially
Explanation: For bulk gas diffusion, increasing pressure increases molecular collision frequency and reduces the mean free path, so the diffusivity…
Correct answer: Decreases- A. T
- B. T2
- C. 1/√T
- D. √T
Explanation: Knudsen diffusivity is controlled by molecular-wall collisions and varies as the mean molecular speed.
Correct answer: √T170. _____________ gas is normally employed in B.E.T. method of finding out the surface area of catalyst?
- A. He
- B. H2
- C. CO2
- D. N2
Explanation: Nitrogen adsorption is conventionally used in the BET method because N₂ has suitable size, readily forms a measurable monolayer at…
Correct answer: N2- A. Langmuir's assumption applies to every adsorbed layer
- B. (except the first one) is involved in each of the evaporation process
- C. The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer
- D. There is no dynamic equilibrium between successive layer
- E. None of these
Explanation: BET theory assumes dynamic equilibrium between successive adsorbed layers, so the statement that no such equilibrium exists is not a BET…
Correct answer: There is no dynamic equilibrium between successive layer- A. Sparkler
- B. Pre-coat
- C. Vacuum leaf
- D. Plate and frame
Explanation: A pre-coat of filter aid forms a porous filtering layer that prevents gelatinous solids from sealing the filter medium or plugging the…
Correct answer: Pre-coat- A. Recovery/rejection
- B. Recovery
- C. None of these
- D. Rejection
Explanation: Screen efficiency is generally the product of recovery of the wanted fraction and rejection of the unwanted fraction, not their ratio or…
Correct answer: None of these- A. Stainless steel
- B. Wooden plank
- C. High speed steel
- D. Cast iron
Explanation: Plate-and-frame filter supports are conventionally made of cast iron because it provides a strong, rigid, economical support for the…
Correct answer: Cast iron- A. Plate and flame filter
- B. Leaf filter (Moore filter)
- C. Rotary drum filter
- D. Sand filter
Explanation: A plate-and-frame filter is a pressure filter because slurry is forced through the filter cloth by applied pressure.
Correct answer: Plate and flame filter- A. Nylon
- B. Cotton fabric
- C. Metal cloth of monel or stainless steel
- D. Glass cloth
Explanation: Cotton fabric is unsuitable for strongly corrosive liquids because it can be chemically attacked and degraded.
Correct answer: Cotton fabric- A. Agitation
- B. Filtration
- C. Size enlargement
- D. Humidification
Explanation: Humidification transfers water vapour into air and is therefore a gas-liquid mass-transfer operation, not a mechanical operation.
Correct answer: Humidification- A. Sand
- B. Shell & leaf
- C. Plate & frame
- D. Rotary vacuum
Explanation: A sand filter is effective for clarifying a large water flow containing only a small concentration of suspended precipitate.
Correct answer: Sand- A. 0.5
- B. < 1
- C. 1
- D. √3
Explanation: Sphericity equals the surface area of an equal-volume sphere divided by the actual particle surface area, and it is 1 only for a sphere.
Correct answer: < 1- A. Sodium silicate
- B. Lime
- C. Quartz
- D. Alumina
Explanation: Quartz is an inert mineral and is not normally used as a surface-active or conditioning agent in flocculation.
Correct answer: Quartz