chemical engineering mass transfer MCQs – Page 28

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 Review each marked answer and report any item that may be outdated or unclear.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

541. If a1 and a2 are the relative volatilities when the pressure in the distillation column is 1 and 2 atm respectively. Pick out the correct statement ?
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A. a1 = 2a2

B. a1 = 0.5 a2

C. a1 = a2

D. None of these

542. Pick out the correct statement ?
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A. Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the

B. tillation</strong>

C. A sharp decrease in pressure drop is an indication of flooding in a distillation coloumn

D. ber of theoretical stages required for the separation of non-ideal binary system by

E. Flash distillation is suitable for separating components which have very close boiling

F. perature

543. Pick out the wrong statement ?
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A. perature</strong>

B. Relative volatility of a binary mixture changes appreciably with the minor change in

C. Flash distillation is practised on wide spread scale in petroleum refinery

D. The relative volatility of a binary mixture at Azeotropic composition is unity

E. Constant pressure distillation cannot separate an Azeotropic mixture

544. An ideal tower packing should not _______________________?
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A. Have large surface area per unit volume

B. Hold up large amount of liquid in the packing

C. Have large free cross-section

D. Have low weight per unit volume

545. Heat load in a cooling tower______________________?
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A. Means the amount of heat thrown away (KCal/hr.) by the cooling tower

B. Is equal to the number of kg, of water circulated times the cooling range

C. Both A. & B.

D. Neither A. nor B.

546. _____________ temperature is the steady state temperature attained by a small amount of liquid evaporating into a large quantity of unsaturated gas-vapor mixture ?
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A. Wet bulb

B. Dry bulb

C. None of these

D. Dew point

547. The operating line for an absorber is curved, when plotted in terms of _______________________?
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A. Partial pressure

B. Mass fractions

C. Mole ratios

D. Mole fractions

548. Solvent used in extractive distillation_________________________?
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A. Is of low volatility

B. Does not alter the relative volatility of the original components

C. Forms a low boiling azeotrope

D. Forms a high boiling azeotrope

549. The dimension of diffusivity is same as that of the__________________?
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A. Molal concentration

B. Velocity head

C. Kinematic viscosity

D. dimension of diffusivity is same as that of the

E. Density

550. Occurrence of case hardening during drying of a high moisture solid cake _______________ the drying rate?
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A. Exponentially increases

B. Does not affect

C. Increases

D. Decreases

551. The rate of mass transfer is not dependent upon the______________________?
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A. Degree of dispersion of one fluid in the other

B. Interfacial surface exposed between the phases

C. Both A. & B.

D. None of these

552. The absorption factor is defined as (where, L = liquid flow rate, G = gas flow rate and, m = slope of the equilibrium line) ?
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A. LG/m

B. L/mG

C. mL/G

D. G/mL

553. When the feed to a distillation column is a saturated liquid, slope of the feed line is_____________________?
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A. Unity

B. Zero

C. None of these

D. Infinity

554. Water-ethyl alcohol solution can be concentrated (in respect of alcohol concentration) by ________________ distillation?
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A. High pressure

B. Atmospheric

C. None of these

D. Vacuum

555. Pick out the correct statement?
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A. For a given separation in a binary distillation column, with increase in reflux ratio (above the

B. Kremser-Brown-Souders equation is used to calculate the efficiency of a plate tower

C. tifying operating lines are vertical at total reflux</strong>

D. The slope of the stripping line is always less than unity

E. imum reflux ratio), the fixed cost of the distillation column first increases and then

F. In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and

556. In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG ______________ the absorption factor?
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A. Increases with increase in

B. Is one at unity value of

C. Both A. and B.

D. Neither A. nor B.

557. If mass diffusivity in a mixture is equal to the thermal diffusivity, then the Lewis number is____________________
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A. 1

B. 1

C. 0

558. Which of the following quantities need not be fixed before starting the design of a cocurrent absorber ?
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A. Heat gain or loss

B. None of these

C. Flow rate of entering liquid

D. Flow rate of gas

559. The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or outgassed adsorbent to from a definite concentration of adsorbate is called its_____________________?
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A. Integral heat of adsorption

B. Heat of wetting

C. Heat of normal condensation

D. Differential heat of adsorption

560. With increase in pressure, the relative volatility for a binary system_________________?
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A. Increases

B. Decreases

C. Remains same

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

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