chemical engineering mass transfer MCQs – Page 26

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 Review each marked answer and report any item that may be outdated or unclear.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
501. Humid volume, at a given temperature is a/an _______________ function of humidity?
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A. Logarithmic

B. Exponential

C. Inverse

D. Linear
502. In a distillation column, with increase in the reflux ratio, the heat removed in the cooler ______________________?
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A. Decreases

B. Remains unaffected

C. Increases

D. And the heat required in reboiler decreases

503. Tea percolation employs___________________________?
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A. Leaching

B. Liquid-liquid extraction

C. Absorption

D. None of these

504. Ordinary diffusion process is also called ______________ diffusion?
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A. Concentration

B. Pressure

C. Forced

D. Thermal

505. Steam distillation is used for separation of high boiling ____________________?
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A. Substances from non-volatile impurities

B. Volatile impurity from still higher boiling substances

C. Both A. and B.

D. Neither A. nor B.

506. During constant rate drying period, vaporisation rate per unit drying surface area _____________________?
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A. Does not change with time

B. Increases with time

C. Does not affect the moisture content of the wet solid

D. Decreases with time

507. Fractional solvent extraction______________________?
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A. Results in low interfacial tension

B. Employs only one solvent

C. None of these

D. Employs two solvents
508. Selectivity of the solvent used in solvent extraction should be)_________________?
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A. > 1

B. 1

C. < 1

D. 0

509. Tray spacing in a distillation column of dia 10-12 ft. used in petroleum refinery may be around _____________ inches?
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A. 100

B. 60

C. 30

D. 5

510. The feed to fractionating column is changed from saturated vapour to saturated liquid. If the separation and reflux ratio remains unchanged, the number of ideal stages will______________________?
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A. Depend on saturated boiling point; may increase or decrease

B. Increase

C. Remain same

D. Decrease

511. During bottling of cold drinks (e.g. Pepsi), the main resistance to mass transfer for the absorption of carbon dioxide in water lies in the___________________?
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A. None of these

B. Liquid-gas interface

C. Liquid film

D. Gas film

512. When the ____________________ the relative humidity of air decreases, despite an increase in the absolute humidity?
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A. Temperature falls

B. Temperature rises

C. Pressure rises

D. Pressure falls

513. The efficiency of a plate column will be maximum, when the flow is ideal __________________ the plate?
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A. Across

B. Above

C. Both A. & B.

D. Neither A. nor B.

514. Flights in a rotary dryer are provided to________________?
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A. Reduce the residence time of solid

B. Increase the residence time of the solid

C. Lift and shower the solids thus exposing it thoroughly to the drying action of the gas

D. None of these

515. The relation, Sc = Pr = 1, is valid, when the mechanism of ______________ transfer is same?
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A. Heat and mass

B. Heat and momentum

C. Mass and momentum

D. Heat, momentum and mass

516. In the absorption of ammonia in water, the main resistance to absorption is by the _________________ phase?
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A. Liquid

B. Gas

C. Both A. & B.

D. Neither A. nor B.

517. Separation of a mixture of two gases by absorption in the liquid solvent depends upon the difference in their____________________?
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A. Density

B. Relative volatility

C. Solubility

D. Viscosity

518. In case of non-ideal gases and liquids, the molal diffusivity ________________?
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A. Is independent of pressure

B. Is equal to the volumetric diffusivity

C. Varies directly as the pressure

D. Varies inversely as the pressure

519. Which of the following is not a unit of mass transfer co-efficient ?
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A. Moles transferred/ [(time) (area) (pressure)]

B. None of these

C. Moles transferred/ [(time) (area) (mole fraction)]

D. Moles transferred/ [(time) (area) (mass A/mass B)]

520. Which of the following equipments is not used for liquid dispersion ?
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A. Wetted wall towers

B. Agitated vessels

C. Venturi scrubbers

D. Packed towers