chemical engineering mass transfer MCQs – Page 29

Practise multiple-choice questions from chemical engineering mass transfer for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering mass transfer Mcqs
561. Separation of two or more components of a liquid solution cannot be achieved by___________________?
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A. Liquid extraction

B. Fractional crystallisation

C. Evaporation

D. Absorption
562. Which of the following unit operations makes use of Thiele-Geddes equation ?
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A. Liquid-liquid extraction

B. Solid-liquid extraction

C. Multi-component distillation

D. Multi-component absorption with chemical reaction

563. The equipment frequently used for adiabatic humidification-cooling operation with recirculating liquid is_________________?
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A. Spray chamber

B. Natural draft cooling tower

C. Induced draft cooling tower

D. None of these

564. (NSh/NRe.NSc) is termed in mass transfer operation as the __________________________?
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A. Stanton number

B. Peclet number

C. Thermal diffusivity

D. Momentum diffusivity

565. Overall efficiency of the distillation column is _____________________?
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A. The ratio of number of ideal plates to actual plates

B. The ratio of number of actual plates to ideal plates

C. Same as the Murphree efficiency

D. Always more than the point efficiency

566. Which of the following remains constant during evaporative cooling process with recirculated water supply ?
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A. None of these

B. Partial pressure of vapour

C. Relative humidity

D. Wet bulb temperature
567. Minimum possible diameter of a packed column is decided mainly by the________________________?
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A. Liquid density

B. Flooding

C. Gas viscosity

D. Liquid hold up

568. Inside the distillation columns, the ________________________?
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A. Driving force for the liquid flow is its weight

B. Vapors are not always at their dew points

C. Highest temperatures is near the feed plate

D. All A., B. and C.

569. _____________ is used as an entrainer for the separation of acetic acid-water mixture by distillation?
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A. Furfural

B. Hexane

C. Butyl acetate

D. Benzol

570. If G = insoluble gas in gas stream and L = non-volatile solvent in liquid stream, then the slope of the operating line for the absorber is___________________?
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A. Always < 1

B. L/G

C. None of these

D. G/L

571. Dew point of a gas-vapour mixture_____________________?
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A. Decreases with temperature rise

B. Increases with increase in pressure

C. Decreases with decrease in pressure

D. Increases with temperature rise

572. Pick out the wrong statement?
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A. The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are the same

B. ws negative deviation from Raoults Law

C. 1 Nm3 of dry air is lighter than 1Nm3 of humid air

D. An Azeotropic mixture of two liquids has boiling point higher than either of them, when it

E. The Lewis number of a mixture is unity, when the thermal diffusivity is equal to the mass

F. fusivity

573. Leaching of sugar from sugar beets is done by___________________?
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A. Lime water

B. Hot water

C. Dilute H2SO4

D. Hexane

574. ______________ column is the most suitable for achieving the best performance for mass transfer operations involving liquid with dispersed solids ?
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A. Plate

B. Packed

C. Wetted wall

D. Spray

575. The binary diffusivity in gases does not depend upon the ___________________?
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A. Pressure

B. None of these

C. Temperature

D. Nature of the components

576. At minimum reflux ratio for a given separation__________________?
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A. Number of plates is infinity

B. Number of plates is zero

C. Separation is most efficient

D. Minimum number of the theoretical plates is required

577. The diffusivity D. in a binary gas mixture is related to the temperature (T) as________________________?
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A. D ? T1.5

B. D ? T2

C. D ? T0.5

D. D ? T

578. Pick out the wrong statement pertaining to leaching ?
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A. Door classifier can be used for leaching of coarse solids

B. Fine solids cannot be leached in a Pachuca tank

C. Very high temperature is not needed for the leaching of sugar beet

D. Vegetable seeds can be leached in either of Bollman extractor, Rotocel or Kennedy extractor

579. The Knudsen diffusivity is dependent on the ______________________?
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A. Molecular velocity only

B. Molecular mean free path only

C. Molecular velocity and pore radius of the catalyst

D. Pore radius of the catalyst only

580. Stacked packing compared to dumped packing_________________?
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A. Provides poorer contact between the fluids

B. Gives lower pressure drop

C. Both A. and B.

D. Gives higher pressure drop