chemical engineering mass transfer MCQs – Page 13

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 Review each marked answer and report any item that may be outdated or unclear.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

241. The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m2/m3)_________________?
0

A. 900

B. 1200

C. 800

D. 500

242. Pick out the wrong statement ?
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A. In case of a stripper, the equilibrium curve is always below the operating line

B. Absorption factor is constant, when the equilibrium and operating lines are straight

C. In case of an absorber, the operating line is always above the equilibrium curve

D. In the absorption of low solubility gases, the liquid film is the controlling resistance

243. According to Poiseuilles law, the permeability for gas flow through a capillary is proportional to (where, ? = gas viscosity)___________________?
0

A. 1/?

B. ??

C. ?2

D. ?

244. Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the ___________________ moisture ?
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A. Critical

B. Free

C. Unbound

D. Bound

245. The individual mass transfer co-efficients (moles/m2s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling ?
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A. Liquid side

B. Gas side

C. Interfacial

D. Both liquid and gas side

246. Which of the following can be calculated theoretically using steam table and Daltons law of partial pressure; if the relative humidity and dry bulb temperature of moist air is known ?
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A. Humidity ratio

B. None of these

C. Wet bulb temperature

D. Dew point

247. Alcohol is dehydrated using _______________________ distillation?
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A. Extractive

B. Azeotropic

C. Molecular

D. Steam

248. Pick out the wrong statement ?
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A. nomy

B. With increase in pressure, the solubility of gases in solvent increases at a fixed temperature

C. In solvent extraction, the distribution co-efficient should be as large as possible for solvent

D. The capacity of a distillation column is maximum at total reflux

E. Decrease in Murphree plate efficiency is an indication of entrainment in distillation column

249. The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is__________________?
0

A. -ve

B. #NAME?

C. ?

D. 0

250. Even though bubble cap towers are very effective for humidification operation, they are not used commonly in industries, because of the_________________?
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A. High evaporation losses of water

B. Difficulty in its fabrication

C. High pressure drop of the gas

D. None of these

251. It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%) ?
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A. 51 min

B. 15 min

C. 94 min

D. 71 min

252. In a binary distillation column, if the feed contains 40 mole % vapour, the q line will have a slope of_________________?
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A. 1.5

B. 0.6

C. -0.6

D. -1.5

253. Flash distillation is _______________________?
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A. Same as simple distillation

B. Used for multi-component systems like crude refining

C. Most useful for handling binary systems

D. Same as differential distillation

254. Relative volatility varies with the concentration of component for an ideal solution. The relative volatility of a binary mixture may be defined as the ratio of vapor pressure of component A to that of component B, when_________________?
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A. Vapor phase obeys Daltons law and liquid phase obeys Raoults law

B. Liquid phase obeys Daltons law and vapor phase obeys Raoults law

C. Only vapor phase follows Raoults law

D. Only liquid phase obeys Daltons law

255. Alcohol is dehydrated using ______________ distillation?
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A. Extractive

B. Molecular

C. Azeotropic

D. Steam

256. In a gas-liquid absorption column, for obtaining the maximum absorption efficiency____________________?
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A. Liquid stream should be distributed uniformly

B. Gas stream should be distributed uniformly

C. Both gas as well as liquid streams should be distributed uniformly

D. By passing should be completely avoided

E. wer: Option C

257. For gas absorption, low viscosity solvents are preferred, because of their ____________________?
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A. Better flow characteristics

B. Rapid absorption rates

C. All A., B. and C.

D. Low pumping pressure drop

258. Freundlich equation applies to the adsorption of solute from___________________?
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A. Dilute solutions, over a small concentration range

B. Concentrated solutions

C. Gaseous solutions at high pressure

D. None of these

259. Rayleigh equation applies to _________________ distillation ?
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A. Molecular

B. Differential

C. Flash

D. Equilibrium

260. Penetration theory relates the average mass transfer co-efficient (K) with diffusivity D. as____________________?
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A. K ?D2

B. K ??D

C. K ?D

D. K ?D1.5

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