chemical engineering mass transfer MCQs – Page 25

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 Review each marked answer and report any item that may be outdated or unclear.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

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

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