chemical engineering mass transfer MCQs – Page 23

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 Review each marked answer and report any item that may be outdated or unclear.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

441. Flooding in a vapor-liquid contacting equipment occurs in a tray, when the pressure drop through a tray is _______________ the liquid head available in the downcomer?
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A. Same as

B. Less than

C. Very much less

D. More than

442. The solvent used in liquid-liquid extraction should have _______________ less than one?
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A. Selectivity

B. Distribution co-efficient

C. Both A. and B.

D. Neither A. nor B.

443. Absorption factor is defined as (where, S1 = slope of the operating line S2 = slope of the equilibrium curve) ____________________?
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A. S1 S2

B. S2/S1

C. S1/S2

D. S1 S2

444. An alkaline solution is used to reduce the concentration of carbon dioxide in a stream from 10% to 0.1% by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is ?
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A. 100

B. 4.605

C. 9.21

D. 0.001

445. Which of the following is an undesirable characteristic for the solvent used in gas absorption ?
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A. Low viscosity

B. High gas solubility

C. None of these

D. Low vapor pressure

446. Which of the following adsorbent is used to decolourise yellow glycerine ?
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A. Fullers earth

B. Alumina

C. Silica gel

D. Activated carbon

447. Flash distillation is suitable for separating the constituents of a binary system, which _____________________?
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A. Have very close boiling points

B. Have very wide boiling points

C. Form constant boiling azeotrope

D. Form minimum boiling azeotrope

448. _______________ diffusion is used for separating the isotopes of methane ?
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A. Thermal

B. Concentration

C. Force

D. Pressure

449. In a distillation operation, what is the effect of the temperature of the reflux stream (given below) on the condenser and reboiler loads? Reflux conditions: (i) Reflux stream is completely liquid and is at its bubble point. (ii) Reflux stream is below its bubble point ?
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A. Condenser and reboiler loads are the same in both the cases

B. Reboiler load is the same in both the cases but condenser load is higher in case (ii)

C. Condenser load is the same in both the cases but reboiler load is higher in case (ii)

D. Both condenser and reboiler loads are higher in case (ii) as compared to case (i)

450. In McCabe-Thiele method, at infinite reflux ratio________________?
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A. The overhead product is minimum

B. Both the operating lines coincide with diagonal

C. Both A. and B.

D. Neither A. nor B.

451. The film penetration model of mass transfer was enunciated by______________________?
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A. Gilliland

B. Stefan

C. Toor and Marcello

D. Fick

452. Steady state equimolal counter diffusion occurs in case of ____________________?
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A. Absorption

B. Leaching

C. Binary phase distillation

D. Liquid-liquid extraction

453. (NRe . NSc) is termed in mass transfer operation as the ______________ number?
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A. Sherwood

B. Stanton

C. None of these

D. Peclet

454. In case of a desorber (stripper), the________________?
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A. Operating line always lies below the equilibrium curve

B. Operating line always lies above the equilibrium curve

C. Temperature always increases

D. Temperature remains unaffected

455. The overall mass transfer co-efficient for the absorption of SO2 in air with dilute NaOH solution can be increased substantially by___________________?
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A. Increasing the total pressure

B. Increasing the liquid film co-efficient

C. Decreasing the total pressure

D. Increasing the gas film co-efficient

456. In an operating distillation column, the______________________?
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A. Vapors and liquids are at their dew point and bubble point respectively

B. Driving force for the liquid flow is its specific weight

C. bottom to the top of the column</strong>

D. Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from

E. Highest temperature is encountered at the top of the column

457. Decoction refers to the use of solvent________________?
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A. None of these

B. At ambient temperature

C. In its vapor form

D. At its boiling point

458. Flooding in a column results due to___________________?
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A. Low velocity of the liquid

B. High temperature

C. High pressure drop

D. Low pressure drop

459. Which of the following equipments is not used in liquid-liquid extraction ?
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A. Packed towers

B. Centrifugal extractors

C. Agitated vessels

D. Pachuka tank

460. If the specific heats of a gas and a vapor are 0.2KJ/Kg.K and 1.5 KJ/Kg.K respectively, and the humidity is 0.01; the humid heat in KJ/Kg. is________________?
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A. 0.107

B. 0.31

C. 0.017

D. 0.215

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