71. If Rm is the minimum reflux ratio, the optimum reflux ratio may be around __________ Rm.
1.2 to 1.5
2.5 to 3
3 to 4
5
✅ The correct answer is option A.
Mass Transfer MCQs
72. In distillation columns, the number of bubble caps per tray primarily depends upon the
Allowable liquid velocity
Allowable gas velocity
Allowable gas and liquid velocities
Feed composition
✅ The correct answer is option C.
73. Inside the distillation columns, the
Highest temperatures is near the feed plate
Driving force for the liquid flow is its weight
Vapors are not always at their dew points
All of the above
✅ The correct answer is option B.
74. Large scale usage of flash distillation is practised in
Soap manufacturing
Ammonia synthesis plant
Polymerisation industry
Petroleum refinning
✅ The correct answer is option D.
75. The surface renewal frequency in Danckwerts model of mass transfer is given by (KL: mass transfer co-efficient)
√(KL².DA)
KL².DA
KL²/DA
KL/DA²
✅ The correct answer is option A.
76. Boiling point diagram is not affected by the ambient
Pressure
Humidity
Temperature
Both B and C
✅ The correct answer is option D.
77. In case of an unsaturated mixture of gas and vapor, the percentage saturation is __________ its relative saturation.
Lower than
Higher than
Equal to
Either A or B, depends on the mixture composition
✅ The correct answer is option A.
78. The dew point of a saturated gas phase equals the __________ temperature.
Gas
Room
Wet bulb
None of these
✅ The correct answer is option A.
79. Under conditions of flooding in packed tower, the gas pressure drop
Decreases rapidly
Increases rapidly
Remains constant
Is maximum
✅ The correct answer is option D.
80. Which of the following is an undesirable property for an absorbing solvent?
Low vapour pressure
Low velocity
Low freezing point
None of these
✅ The correct answer is option D.