chemical engineering mass transfer MCQs – Page 4

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 Review each marked answer and report any item that may be outdated or unclear.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
61. The most efficient cooling tower out of the following is_____________________?
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A. Induced draft

B. Atmospheric

C. Forced draft

D. Natural draft

62. Which of the following is considered equivalent to one theoretical stage in Mc-Cabe Thieles method ?
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A. Partial condenser

B. Total condenser

C. Reboiler

D. Both B. and C
63. With increase in the liquid flow rate at a fixed gas velocity in a randomly packed counter current gas-liquid absorption column, the gas pressure drop___________________?
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A. Remains unchanged

B. Increases

C. Decreases exponentially

D. Decreases

64. Co-current absorbers are usually used when the gas to be dissolved in the liquid is ___________________?
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A. Highly soluble

B. Sparingly soluble

C. A pure substance

D. A mixture

65. Plate efficiency_______________________?
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A. Increases due to foaming

B. Increases due to weeping and dumping of liquid

C. Increases due to liquid entrainment

D. Is a function of the mass transfer between liquid and vapour
66. Which of the following parameters remains constant during chemical dehumidification ?
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A. Wet bulb temperature

B. None of these

C. Partial pressure of vapour

D. Dry bulb temperature
67. The slope of 9-line is determined by the__________________?
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A. Plate efficiency to be achieved

B. Relative volatility

C. Thermal condition of the feed

D. Reflux ratio

68. 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

69. Molecular distillation is_____________________?
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A. High temperature distillation

B. For heat-sensitive materials

C. Very low pressure distillation

D. Both B. and C.
70. With increase in the mass velocity of the gas, the rate of drying during the constant rate period ______________, if the conduction and radiation through the solid are negligible ?
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A. Remain same

B. Increases linearly

C. Increases

D. Decreases

71. At 750K and 1 atm, the approximate value of Schmidt number for air is_________________?
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A. 0.01

B. 10

C. 0.1

D. 1

72. In gas-liquid contact operation, the number of ideal stages, N = (xa xb)/(xb x*b). This is true when the stripping factor S is ________________?
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A. S = 1

B. S > 1

C. S = ?

D. S < 1

73. Operating velocity in a packed tower is usually __________________ the flooding velocity ?
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A. Twice

B. More than

C. Equal to

D. Half
74. The Hatta number is important in______________________?
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A. Gas absorption without chemical reaction

B. Multi-component distillation

C. Binary distillation

D. Gas absorption with chemical reaction
75. The reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. The reflux ratio is____________________?
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A. 0.5

B. 50

C. 2

D. 150

76. Which of the following increases during evaporative cooling process with recirculated water supply ?
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A. Wet bulb temperature

B. Relative humidity

C. Partial pressure of vapour

D. Both B. and C.
77. Pick out the wrong statement. Raoults law does not apply, when the______________________?
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A. mation of solution

B. Component molecules are non-polar

C. Chemical combination or molecular association between unlike molecules takes place in the

D. Size of component molecules are not equal

E. Attractive forces between like and unlike molecules in the solution are approximately equal

78. H2S present in naphtha reformed gas is removed by absorbing with___________________?
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A. HCl

B. Ethanolamine

C. K2CO3

D. Vacuum gas oil

79. Pick out the wrong statement ?
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A. Mechanical agitation is required, if the system has low interfacial tension

B. Sieve tray towers are generally used for systems having low interfacial tension

C. When Henrys law constant is very small, then the mass transfer rate is controlled by the gas

D. m resistance

E. Taylor-Prandtl analogy for heat and mass transfer considers the transfer through both laminar

F. turbulent layers

80. Drying of a solid involves _________________ transfer ?
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A. Only heat

B. Only mass

C. Both heat and mass

D. None of these