chemical engineering MCQs – Page 92

Practise multiple-choice questions from chemical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering Mcqs
1821. For an absorber, both equilibrium and operating line will be straight for _______________________?
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A. Concentrated solution and isothermal operation

B. Dilute solution and non-isothermal operation

C. Dilute solution and isothermal operation

D. Concentrated solution and non-isothermal operation

1822. Mass transfer co-efficient varies as DAB 0.5, according to the _______________ theory?
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A. None of these

B. Penetration

C. Surface renewal

D. Film

1823. Pick out the wrong statement?
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A. Mass transfer co-efficient does not account for gas-liquid diffusion

B. Diffusion co-efficient and mass transfer co-efficient are not same in any mass transfer

C. ration

D. Contacting cold vapor-gas mixture with hot liquid exemplifies humidification process

E. Contacting cold liquid with warm vapor-gas mixture exemplifies dehumidification process

1824. Reverse osmosis is also called_________________?
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A. Ultra-filtration

B. Dialysis

C. Diffusion

D. Electrodialysis

1825. Separation of the isotopes of helium for scientific investigations is done by_____________________?
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A. Leaching

B. Thermal diffusion

C. Solvent extraction

D. Reverse osmosis

1826. The relative saturation of a partially saturated mixture of vapour and gas can be increased by ________________ of the mixture?
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A. Reducing the total pressure

B. Increasing the total pressure

C. Reducing the temperature

D. Both B. and C.
1827. In McCabe-Thiele method, at infinite reflux ratio___________________?
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A. Number of plates is maximum

B. Overhead product is maximum

C. Both the operating lines coincide with the diagram

D. None of these

1828. At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbent __________________?
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A. Increases exponentially

B. Remains unchanged

C. Increases

D. Decreases
1829. Unit operation involved in the prilling of urea is_____________________?
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A. Evaporation

B. Drying

C. Crystallisation

D. Both B. and C.
1830. Cox chart is useful in the design of___________________?
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A. Evaporator

B. Distillation column

C. Crystalliser

D. Dryer

1831. Pick out the correct relationship. (Where, Ri = internal reflux ratio Ro = external reflux ratio.) ?
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A. (1 + Ri) = Ro/Ri

B. (1 Ri) = Ro/Ri

C. (1 Ro) = Ro/Ri

D. (1 + Ro) = Ro/Ri
1832. _______________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower?
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A. Lewis

B. Sherwood

C. Peclet

D. Stanton

1833. The temperature of water cooled in cooling tower is always _________________ temperature of entering air?
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A. Equal to the dry bulb

B. Equal to the wet bulb

C. More than the wet bulb

D. Less than the wet bulb

1834. Steady state equimolal counter diffusion is encountered in_____________________?
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A. All liquid-liquid diffusion systems

B. All liquid-solid diffusion systems

C. Separation of a binary mixture by distillation

D. Absorption of NH3 from air by water

1835. Mass transfer co-efficient is directly proportional to DAB according to the _____________ theory?
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A. Penetration

B. None of these

C. Surface-renewal

D. Film
1836. The cooling effect in a cooling tower cannot be increased by_____________________?
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A. Reducing the humidity of entering air

B. Increasing the air velocity over the wet surfaces

C. Lowering the barometric pressure

D. None of these
1837. According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity) ?
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A. D

B. 1/D

C. D0.5

D. D2

1838. The feed to fractionating column is changed from saturated vapour to saturated liquid. If the separation and reflux ratio remains unchanged, the number of ideal stages will______________________?
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A. Decrease

B. Increase

C. Depend on saturated boiling point; may increase or decrease

D. Remain same

1839. Out of two equilibrium curves, first one lies above the diagonal and the second lies below the diagonal in the x-y plot. It means that separation by distillation is_________________?
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A. More readily done in the second case compared to first one

B. None of these

C. Not possible in the second case unless high pressure is applied

D. Not possible in the second case unless vacuum is applied

1840. 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. At the same relative humidity

B. And dehumidified with increase in wet bulb temperature

C. And dehumidified with decrease in wet bulb temperature

D. And humidified