chemical engineering mass transfer MCQs – Page 35

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 Review each marked answer and report any item that may be outdated or unclear.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

681. Ponchon-Savarit method analyses the fractional equipment based on___________________?
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A. Enthalpy balance only

B. Material balance only

C. Both enthalpy and material balances

D. The assumption of constant molal-overflow

682. Diffusivity in concentrated solutions differs from that in dilute solutions, because of the changes in ____________________?
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A. Viscosity with concentration

B. Degree of ideality of the solution

C. Both A. and B.

D. Neither A. nor B.

683. In a counter-current extractor, as the axial mixing increases, the extraction efficiency______________________?
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A. Remains unchanged

B. Increases

C. Decreases

D. Depends on the pressure of the system

684. A mixture of 10% C6H6 vapour in air at 25C and 750 mm Hg has a dew point of 20C. Its dew point at 30C and 700 mm Hg will be around _______________ C?
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A. 27.3

B. 18.7

C. 20

D. 21.7

685. In case of an absorber, the operating _______________?
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A. Line always lies above the equilibrium curve

B. Velocity is more than the loading velocity

C. Line can be either above or below the equilibrium curve

D. Line always lies below the equilibrium curve

686. Air at a particular humidity is heated in a furnace. The new dew point_____________________?
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A. Decreases

B. Remain unchanged

C. Increases

D. Depends on the extent of heating

687. Channelling in a packed tower results from the_____________________?
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A. High pressure drop

B. Maldistribution of liquid

C. Non-uniformity of packing

D. Both B. and C.

688. Sides of equilateral-triangular co-ordinates (on which ternary liquid system is plotted) represent ______________________?
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A. A binary mixture

B. A ternary mixture

C. A pure component

D. Partially miscible ternary system

689. In a binary system, separation is very efficient, when the relative volatility is_______________?
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A. > 1

B. < 1

C. 1

D. 0.5

690. Which of the following same diameter columns gives lowest pressure drop per unit height ?
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A. Packed column (stacked)

B. Randomly packed column

C. Bubble-cap column

D. Sieve-plate column

691. The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = _________________?
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A. 1

B. 0

C. 10

D. 0.5

692. Langmuir equation is associated with________________________?
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A. Adsorption

B. Multi-component absorption

C. Leaching

D. Steam distillation

693. The minimum number of theoretical plates is required for achieving a given separation in distillation column with_________________?
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A. No reflux

B. Zero reflux ratio

C. Minimum reflux ratio

D. Total reflux

694. As the reflux ratio in a distillation column is increased from the minimum, the______________________?
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A. Total cost first decreases and then increases

B. Slope of the operating line in stripping section decreases

C. Number of plates decreases very slowly first and then more and more rapidly

D. Liquid flow increases while the vapor flow decreases for a system

695. For the same process conditions, the reflux ratio of an unlagged distillation column___________________?
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A. Increases in summer

B. Increases in winter

C. Decreases in winter

D. None of these

696. Critical humidity of a solid salt means the humidity_____________________?
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A. Above which it will always become damp

B. Below which it will always stay dry

C. Both A. and B.

D. Above Which it will always become dry and below which it will always stay damp

697. Which of the following liquid-vapor contacting devices provides maximum contact surface area for a particular duty ?
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A. Bubble cap column

B. Randomly packed column

C. Wetted wall column

D. Sieve plate column

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