chemical engineering mass transfer Mcqs
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
461. In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalent to a theoretical plate HTUOG = overall gas phase height of a transfer unit) ?
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A. Straight

B. Parallel

C. Both A. & B.

D. Neither A. nor B.

462. Relative volatility does not change appreciably with the change in_____________________?
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A. Total pressure

B. Vapour pressure of either component

C. Temperature

D. None of these

463. Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the _______________ moisture?
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A. None of these

B. Critical

C. Bound

D. Unbound

464. _______________ column is used in gas absorption process ?
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A. Bubble cap

B. Packed

C. Wetted wall

D. Sieve/perforated tray

465. Extraction of coffee from its seed is done by___________________?
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A. Liquid-liquid extraction

B. Steam distillation

C. Extractive distillation

D. Leaching

466. On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapor feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in______________________?
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A. None of these

B. Increased reflux ratio

C. Greater degree of separation with a fixed number of trays

D. Increased reboiler load

467. In case of absorption, both the operating and equilibrium lines will be straight for______________?
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A. Dilute solutions

B. None of these

C. Isothermal operation

D. Dilute solutions and isothermal operation
468. _________________ is the separation technique used for desalination of sea water ?
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A. Adsorption

B. Reverse osmosis

C. Thermal diffusion

D. Absorption

469. For absorbing a sparingly soluble gas in a liquid ___________________?
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A. Liquid side mass transfer co-efficient should be increased

B. Liquid side mass transfer co-efficient should be decreased

C. Gas side mass transfer co-efficient should be increased

D. Mass transfer co-efficient must be kept constant

470. When the solvent dissolves very little of solute, then__________________________?
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A. Solvent of low freezing point should be used

B. Large quantity of solvent is required to extract the solute

C. Solvent of low latent heat of vaporisation should be used

D. Very small quantity of solvent is required

471. Pick out the system with minimum boiling azeotrope at 1 atm ?
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A. Hydrochloric acid-water

B. Ethyl alcohol-water

C. Benzene-toluene

D. All A., B. and C.

472. The reciprocal of stripping factor is termed as ________________________?
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A. Absorption factor

B. Murphree efficiency

C. Selectivity index

D. Relative volatility

473. Wetted wall tower experiment determines the__________________?
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A. Molal diffusivity

B. None of these

C. Mass transfer co-efficient

D. Volumetric co-efficient

474. During dehumidification of unsaturated air wet bulb temperature & partial pressure of vapor are not constant. However, during evaporative cooling process with recirculated water supply, the _________________ remains constant ?
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A. Wet bulb temperature

B. Relative humidity

C. None of these

D. Partial pressure of water vapor

475. Diffusion co-efficient generally depends upon the temperature, pressure & the nature of the components of the system. Its dimension is not the same as that of the_________________?
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A. Mass transfer co-efficient

B. Volumetric diffusivity

C. Thermal diffusivity

D. Kinematic viscosity

476. _______________ columns are used for liquid dispersion in a continuous gas phase ?
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A. Bubble cap

B. Packed

C. Sieve plate

D. Pulse

477. The McCabe ?L law states that the____________________?
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A. Linear crystal growth rate depends on the crystal size

B. Linear crystal growth rate does not depend on the crystal size

C. Molar heats of vaporisation of components are nearly equal

D. Linear crystal growth rate depends on the degree of super-saturation

478. Which of the following is a suitable absorbent for removal of H2S from natural gas ?
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A. Monoethanolamine (MEA)

B. Dilute

C. Hot water

D. Vetrocoke solution

479. At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid _______________ that in dry packed tower ?
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A. Is greater than

B. Cannot be predicted as data are insufficient

C. Is same as

D. Is lower than

480. The rough value of diffusion co-efficient of water vapor into air at 25C may be about ______________ cm2/sec?
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A. 1.25

B. 0.25

C. 2.5

D. 0.0025

481. Dew point of an air-water vapor mixture_________________?
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A. All A , B. & C.

B. At constant humidity & total pressure is fixed

C. Decreases with decrease in pressure

D. nt parallel to the temperature axis and to the saturation curve

E. Corresponding to any point on the humidity chart is obtained by projecting a line through this

482. Mass transfer rate between two fluid phases does not necessarily depend on the ______________ of the two phases?
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A. Interfacial area

B. Degree of turbulence

C. Chemical properties

D. Physical properties

483. Equilibrium moisture of a solid is equal to the total moisture minus free moisture. Which of the following substances will have maxi-mum equilibrium moisture ?
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A. Rag paper

B. Anthracite coal

C. Bamboo

D. Inorganic solids

484. In the constant rate period of the rate of drying curve for batch drying,_________________?
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A. Surface evaporation of unbound moisture occurs

B. None of these

C. Rate of drying decreases abruptly

D. Cracks develop on the surface of the solid

485. HETP is numerically equal to HTU, only when the operating line ______________________?
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A. Lies below the equilibrium line

B. And equilibrium lines are parallel

C. Is far from the equilibrium line

D. Lies above the equilibrium line

486. In paper industry, paper is dried in a _____________ dryer ?
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A. Festoon

B. Tunnel

C. Heated cylinder

D. Conveyor

487. The vapour pressure exerted by the moisture contained in a wet solid depends upon the____________________?
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A. All A., B. and C.

B. Nature of the solid

C. Nature of the moisture

D. Temperature

488. Low viscosity absorbent is preferred for reasons of ____________________?
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A. Low pressure drop on pumping

B. Improved flooding characteristics

C. All A., B. and C.

D. Rapid absorption rates and good heat transfer characteristics

489. At constant pressure, with increase of temperature, the dew point will ________________________?
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A. Increase/decrease; depends on the temperature

B. Decrease

C. Increase

D. Remain unchanged

490. 1 kg of a saturated aqueous solution of a highly soluble component A at 60C is cooled to 25C. The solubility limits of A are (0.6 kgA/kg water) at 60C and (0.2 kgA/kg water) at 25C. The amount in kg of the crystals formed is________________________?
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A. 0.175

B. 0.4

C. 0.2

D. 0.25

491. Cox chart is useful in the design of___________________?
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A. Crystalliser

B. Dryer

C. Distillation column

D. Evaporator

492. Which of the following solutions will follow Raoults law most closely ?
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A. 35% solution of camphor in water

B. 35% solution of NH3 in water

C. A solution of polar organic compounds (not of homologue of a series)

D. A solution of benzene, toluene and o-xylene
493. Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of__________________?
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A. Momentum diffusivity to thermal diffusivity

B. None of these

C. Mass diffusivity to momentum diffusivity

D. Thermal diffusivity to mass diffusivity
494. Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the ________________ number?
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A. Stanton

B. Schmidt

C. Peclet

D. Sherwood
495. Unsaturated air (with dry bulb temperature and dew point being 35C and 18C respectively) is passed through a water spray chamber maintained at 15C. The air will be cooled_________________?
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A. And dehumidified with decrease in wet bulb temperature

B. And humidified

C. At the same relative humidity

D. And dehumidified with increase in wet bulb temperature

496. Free flowing granular materials can be best dried in a __________________ drier?
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A. Freeze

B. Drum

C. Rotary

D. Cylinder

497. Mass transfer co-efficient of liquid is____________________?
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A. Affected more by temperature than that for gases

B. Not affected by the temperature

C. None of these

D. Affected much less by temperature than that for gases

498. Milk is dried usually in a __________________ dryer?
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A. Rotary

B. Tray

C. Spray

D. Freeze

499. The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called__________________?
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A. None of these

B. Decoction

C. Percolation

D. Elutriation or elution
500. In physical terms, Schmidt number means _________________?
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A. Thermal diffusivity/mass diffusivity

B. Momentum diffusivity/mass diffusivity

C. Mass diffusivity/thermal diffusivity

D. Thermal diffusivity/momentum diffusivity