chemical engineering mass transfer MCQs – Page 18

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 Review each marked answer and report any item that may be outdated or unclear.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
341. Condensation of a vapour-gas mixture just begins, when (where, p = partial pressure of the vapour P = vapour pressure of the liquid) ?
comments icon0

A. p >>P

B. p < P

C. p << P

D. p = P
342. The binary diffusivity in gases and liquids vary respectively as_________________?
comments icon0
A. T3/2 and T

B. ?T and T3/2

C. T and T3/2

D. T3/2 and ?T

343. Absorption accompanied by heat evolution results in____________________?
comments icon0
A. Decrease in equilibrium solubility

B. None of these

C. Increased capacity of the absorber

D. Increase in equilibrium solubility

344. Heat sensitive materials with very high latent heat of vaporisation may be economically separated using__________________?
comments icon0

A. Evaporation

B. Liquid extraction

C. Absorption

D. Distillation

345. With decrease in the throughput (compared with the design capacity) for a bubble cap distillation column, its efficiency____________________?
comments icon0

A. May increase or decrease; depends on individual design

B. Decreases

C. Remain same

D. Increases
346. The partial pressure distribution of an ideal gas diffusing through another stagnant ideal gas at steady state follows a/an _________________ law?
comments icon0

A. Parabolic

B. Linear

C. Exponential

D. Cubic

347. The diffusion co-efficient in m2/s. of acetic acid in benzene (liquid in liquid) is___________________?
comments icon0

A. 2.09 10-12

B. 2.09 10-5

C. 2.09 10-4

D. 2.09 10-9

348. In distillation columns, the number of bubble caps per tray primarily depends upon the_______________________?
comments icon0

A. Allowable gas velocity

B. Allowable gas and liquid velocities

C. Feed composition

D. Allowable liquid velocity

349. __________________ is concerned with the adsorption equilibria?
comments icon0

A. Gibbs equation

B. Freundlich equation

C. None of these

D. Ficks law

350. _______________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower?
comments icon0

A. Peclet

B. Lewis

C. Stanton

D. Sherwood

351. Molecular diffusion is caused by the________________?
comments icon0

A. Potential energy of the molecules

B. Transfer of molecules from low concentration to high concentration region

C. Thermal energy of the molecules

D. Activation energy of the molecules

352. Which of the following operations does not involve leaching ?
comments icon0

A. Dissolving pharmaceutical products from bark or roots

B. Dissolving gold from ores

C. Removing nicotine from its water solution by kerosene

D. Dissolving sugar from the cells of the beet

353. The caking of crystals can be prevented by _____________________?
comments icon0

A. Maintaining high critical humidity

B. Maintaining low critical humidity

C. Coating the product with inert material

D. Both A. and C.
354. The equipment used in the extraction of highly corrosive radioactive liquids is_______________________?
comments icon0
A. Pulse column

B. Spray column

C. Baffle tower

D. Mixer settler

355. In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y* = 0.9X, where Y* is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer?
comments icon0

A. Less than 2 kg but more than 1 kg of C is transferred to solvent B

B. Less than 1 kg of C is transferred to B

C. No amount of C is transferred to B

D. The entire amount of C is transferred to solvent B
356. Stefans law describes the mass transfer by________________?
comments icon0

A. Diffusion

B. Bulk flow

C. Both A. & B.

D. Neither A. nor B.

357. Which of the following employs an accessory known as drift eliminator ?
comments icon0

A. Rotating disc contactor

B. Multiple effect evaporator

C. Mechanical draft cooling tower

D. Rotary dryer

358. If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that___________________?
comments icon0

A. The system comprises of miscible liquids

B. The system comprises of an azeotrope

C. On heating, a vapor phase will appear; while on cooling, a solid phase will appear

D. The system comprises of partially miscible liquids

359. If f = moles of vapour present per mole of feed, then the slope of feed line is (McCabe- Thiele method) ________________________?
comments icon0
A. -1/f

B. -f/(1 f)

C. (1 f)/f

D. (f 1)/f

360. With increase in temperature, the rate of extraction in leaching (solid-liquid extraction system) ?
comments icon0

A. Increases Linearly

B. Increases

C. Remain unaffected

D. Decreases