chemical engineering mass transfer MCQs – Page 12

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 Review each marked answer and report any item that may be outdated or unclear.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
221. Desulphurisation of petrol is done in a _____________________?
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A. Bollman extractor

B. Plate type extraction column

C. Rotating disc extractor

D. Packed extraction column

222. Molecular diffusivity of a liquid__________________?
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A. Is independent of temperature

B. Decreases with temperature

C. Increases with temperature

D. May increase or decrease with temperature

223. For a binary mixture distillation process, the degree of freedom is 2. However, if the pressure is fixed in this process, the number of independent variables in this process will be ___________________?
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A. 1

B. 2

C. 0

D. 3

224. Though, theoretically the adsorption & desorption isotherms is expected to coincide but sometimes at least a part of the isotherms does not coincide and this phenomenon is known as adsorption hysteresis. In such cases, the desorption equilibrium pressure is ______________ that obtained for adsorption?
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A. Lower than

B. Same as

C. Higher than

D. Either same or higher than

225. At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes______________________?
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A. 1

B. None of these

C. 0

D. ?
226. Water entrained by circulating air in cooling towers is termed as____________________?
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A. Drift

B. None of these

C. Blow down

D. Vapor load

227. For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause ______________ plate requirement?
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A. None of these

B. No change in theoretical

C. Major decrease in the number of

D. Marginal decrease in the number of
228. With the lowering of equilibrium pressure, at a given temperature, the amount of adsorbate on the adsorbent ?
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A. Remain same

B. Decreases

C. Increases

D. Either A. or B., depends on the system

229. The critical moisture content in case of drying indicates the ________________ rate period?
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A. Beginning of falling

B. None of these

C. End of falling

D. Beginning of constant

230. Pick out the wrong statement. Generally for physical adsorption, a gas of________________?
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A. Higher molecular weight is adsorbed in preference to a gas of low molecular weight

B. Low volatility is adsorbed in preference to a gas of high volatility

C. None of these

D. High critical temperature is adsorbed in preference to a gas of low critical temperature

231. Plate towers are preferred to packed towers, when large temperature changes are involved, because of the reason that the____________________?
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A. Pressure drop in the equipment will be very high

B. None of these

C. ipments</strong>

D. Packing may be crushed due to thermal expansion/contraction of the components of the

E. Viscosity variation of the fluids may cause channelling/flooding

232. Can the efficiency of a plate in the distillation tower be greater than 100% ?
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A. Never

B. Normally not; but is possible if infinite number of plates are put

C. Yes

D. Yes; if the reflux ratio is maximum

233. In liquid extraction, if the selectivity is unity, then___________________?
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A. Separation of the constituents is the most effective

B. Solvent flow rate should be very low

C. Amount of solvent required will be minimum

D. No separation will occur
234. Steam distillation is used to__________________?
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A. Increase the total pressure of distillation

B. Increase the efficiency of separation

C. Reduce the number of plates

D. Avoid thermal decomposition of a component
235. The drying time between fixed moisture content within diffusion controlled falling rate period is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid) ?
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A. T

B. ?T

C. T3

D. T2
236. Pick out the wrong statement pertaining to the cooling towers ?
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A. Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb

B. peratur</strong>e

C. A natural draft cooling tower is recommended to be used, when the air humidity is low and air

D. In case of induced draft cooling tower, the fan is placed at the top of the tower

E. perature is also low

F. discharged air

237. For a ternary mixture, in which equilateral triangular co-ordinate is used in leaching and extraction, a ____________ of the equilateral triangular co-ordinates?
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A. Ternary mixture is represented by the sides

B. Binary mixture is represented by any point inside

C. Binary mixture is represented by the apex

D. Pure component is represented by the apex
238. The equation, NA = (DAB . Pt /RTZ) (y1 y2) is for _______________________?
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A. Liquid M.T.C. by penetration theory

B. Ficks first law of diffusion

C. Steady state diffusion for stagnant case

D. Steady state equimolar counter diffusion
239. Weeping in a distillation column_____________________?
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A. Increases tray efficiency

B. Results due to very high gas velocity

C. Provides large interfacial surface for mass transfer

D. Results due to very low gas velocity
240. Rayleighs equation applies to ________________ distillation?
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A. Continuous

B. Steam

C. Differential

D. Flash