chemical engineering mass transfer MCQs – Page 17

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 Review each marked answer and report any item that may be outdated or unclear.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
321. Which is the controlling factor for a drum drier ?
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A. Diffusion

B. Heat transfer

C. Both A. and B.

D. Neither A. nor B.

322. Relative humidity is the ratio of the______________________?
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A. Partial pressure of the vapour to the vapour pressure of the liquid at room temperature

B. Partial pressure of the vapour to the vapour pressure of the liquid at gas temperature

C. Actual humidity to saturation humidity

D. None of these

323. Gaseous diffusivity at atmospheric pressure is of the order of _____________________ cm2/second?
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A. 1 to 5

B. > 10

C. 5 to 10

D. 1
324. Mass transfer co-efficient is directly proportional to DAB 0.5, according to ________________ theory ?
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A. Penetration

B. Film

C. None of these

D. Surface renewal

325. If Rm is the minimum reflux ratio, the optimum reflux ratio may be around _________________ Rm ?
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A. 3 to 4

B. 5

C. 2.5 to 3

D. 1.2 to 1.5
326. Molarity is defined as the number of gm moles of solute per ________________ of solvent?
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A. Litre

B. gm

C. c.c

D. kg

327. The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the ______________ temperature?
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A. Dew point

B. Wet bulb

C. None of these

D. Dry bulb

328. For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is___________________?
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A. Known

B. Unknown

C. Calculated

D. Not required

329. Can a cooling tower cool water below the wet bulb temperature of inlet air ?
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A. Yes; but height of cooling tower will be prohibitively high

B. Yes

C. Yes; but the air flow rate should be excessively high

D. No
330. The shanks system of leaching (i.e., counter-current multiple contact leaching) is used for____________________?
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A. Recovery of tannis from the tree barks and woods

B. Leaching sodium nitrate from Chilean nitrate bearing rock

C. Both A. and B.

D. Neither A. nor B.

331. Fenske equation for determining the minimum number of theoretical stages in distillation column holds good, when the_________________?
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A. Mixture (to be separated) shows positive deviation from ideality

B. Mixture (to be separated) shows negative deviation from ideality

C. Relative volatility is reasonably constant

D. Multi-component distillation is involved

332. Unit of molal diffusivity is____________________?
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A. cm2/sec gm . mole

B. gm moles/cm. sec

C. gm moles/cm2. sec

D. gm moles/cm2 . sec

333. Prandtl number for water at 20C is about ________________?
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A. 0.7

B. 7

C. 70

D. 150

334. At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbent __________________?
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A. Increases exponentially

B. Remains unchanged

C. Decreases

D. Increases

335. Under conditions of flooding in packed tower, the gas pressure drop___________________?
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A. Decreases rapidly

B. Is maximum

C. Remain constant

D. Increases rapidly

336. For a distillation column operating at minimum reflux, the_______________________?
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A. Reflux ratio will be maximum

B. None of these

C. Number of plates required will be maximum

D. Concentration of liquid and vapour leaving a plate will be same

337. In a forced draft cooling tower, water is cooled from 95 to 80F by exposure to air with a wet bulb temperature of 70F. In this case, the________________________?
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A. Range is 15F

B. Approach is 10F

C. Both A. & B.

D. Neither A. nor B.

338. In case of ______________ distillation, a solvent is added to alter the relative volatility of the mixture to be separated?
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A. Molecular

B. Azeotropic

C. Flash

D. Extractive
339. Priming in a distillation column_________________?
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A. Is desirable from point efficiency consideration

B. Results from very low gas velocity

C. Is characterised by the presence of foam throughout the space between trays

D. Reduces the overall pressure drop

340. The ratio of Murphree plate efficiency to point efficiency is always > 1 in a _______________ flow model?
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A. Plug

B. Perfectly mixed

C. Both A. & B.

D. Neither A. nor B.