chemical engineering mass transfer MCQs – Page 14

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 Review each marked answer and report any item that may be outdated or unclear.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

261. For a binary mixture with low relative volatility________________?
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A. An azeotrope may be formed during distillation

B. Use high pressure distillation

C. Use molecular distillation

D. Use steam distillation

262. In case of unsaturated air____________________?
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A. Dew point < wet bulb temperature

B. Wet bulb temperature < dry bulb temperature

C. Both A. and B.

D. Neither A. not B.

263. During sensible cooling process ______________________?
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A. Relative humidity decreases

B. Relative humidity increases

C. Wet bulb temperature decreases

D. Both B. and C.

264. Which of the following processes is followed by unsaturated air (with dry bulb temperature 12C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40C ?
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A. Humidification only

B. Heating only

C. Both heating and humidification

D. Evaporative cooling

265. Which of the following decreases during evaporative cooling process with recirculated water supply ?
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A. Wet bulb temperature

B. Partial pressure of vapour

C. None of these

D. Relative humidity

266. In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is__________________?
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A. Equal to the heat of wetting

B. Equal to the heat of formation of surface compound

C. Called integral heat of adsorption

D. Zero

267. In a vapor-liquid contacting equipment, the overall gas phase mass transfer co-efficient (M.T.C), KG is related to individual co-efficients (KG and KL) as ___________________ ?
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A. 1/KG = 1/KG + m/KL

B. KG = 1/KG + m/KL

C. KG = 1/KL + m/KG

D. 1/KG = 1/KL + m/KG

268. The slope of 9-line is determined by the______________________?
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A. Plate efficiency to be achieved

B. Reflux ratio

C. Thermal condition of the feed

D. Relative volatility

269. In an absorption column, the flooding velocity for random packing is ___________________ that for stacked/regular packing?
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A. Equal to

B. Either A., or B.; depends on the type of packing

C. Greater than

D. Smaller than

270. The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives___________________?
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A. Low pressure drop and high hold up

B. High pressure drop and high hold up

C. Low pressure drop and low hold up

D. High pressure drop and low hold up

271. For a binary mixture with low relative volatility___________________?
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A. Use molecular distillation

B. Use steam distillation

C. Use high pressure distillation

D. An azeotrope may be formed during distillation

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

B. None of these

C. Concentrated solutions

D. Gaseous solutions at high pressure

273. The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is_____________________?
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A. ?

B. -ve

C. 0

D. #NAME?

274. Calculation of mass transfer co-efficient is mostly/normally done using ______________ theory?
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A. Film

B. None of these

C. Penetration

D. Surface renewal

275. The relative saturation of a partially saturated mixture of vapour and gas can be increased by ________________ of the mixture?
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A. Reducing the total pressure

B. Increasing the total pressure

C. Reducing the temperature

D. Both B. and C.

276. An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii) ____________________?
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A. Less number of trays are required

B. Composition of the residue remains unchanged

C. More number of trays are required and the residue composition is more dilute in methanol

D. More number of trays are required but the residue composition remains unchanged

277. If the path of liquid across the plate is very long as in case of large diameter tower, Murphree efficiency can be _______________ percent?
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A. 100

B. None of these

C. > 100

D. < 100

278. Which of the following gas-liquid contacting devices incurs the least pressure drop for a particular duty ?
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A. Perforated tray tower

B. Wetted wall tower

C. Grid tray tower

D. Bubble cap tower

279. An air-water vapour mixture has a dry bulb temperature of 60C and a dew point temperature of 40C. The total pressure is 101.3 kPa and the vapour pressure of water at 40C and 60C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapour/kg of dry air is__________________?
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A. 0.048

B. 0.079

C. 0.122

D. 0.152

280. Humid volume is the total volume in m3 of 1 kg of _____________________?
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A. Vapour laden gas at 1 atm. and room temperature

B. Gas plus its accompanying vapour at 1 atm. and gas temperature

C. Gas plus its accompanying vapour at 1 atm. and room temperature

D. Vapour laden gas at 1 atm. and gas temperature

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