Mass Transfer

61.An example of elution is

  1. Separation of uranium oxide from its ore by H2SO4 in a Pachuca tank
  2. Separation of sugar from sugar beet by hot water
  3. Dissolution of tannin out of tree barks by water
  4. Recovery of vegetable oils from seeds

Correct answer: (A)
Separation of uranium oxide from its ore by H2SO4 in a Pachuca tank

62.An ideal tower packing should not

  1. Have low weight per unit volume
  2. Have large surface area per unit volume
  3. Have large free cross-section
  4. Hold up large amount of liquid in the packing

Correct answer: (D)
Hold up large amount of liquid in the packing

63.As complete saturation of an adsorbent is approached, the differential heat of adsrop-tion approaches

  1. That of normal condensation
  2. Integral heat of adsorption
  3. Zero
  4. None of these

Correct answer: (A)
That of normal condensation

64.As per Gilliland's equation, the diffusivity is

  1. Directly proportional to 'T1.5'
  2. Inversely proportional to 'P'
  3. Dependent on the molecular volume & molecular weight of components
  4. All 'a', 'b' & 'c'

Correct answer: (D)
All 'a', 'b' & 'c'

65.As the reflux ratio decreases, the

  1. Separation becomes more efficient
  2. Number of plates increases
  3. Column diameter increases
  4. None of these

Correct answer: (B)
Number of plates increases

66.As the reflux ratio in a distillation column is increased from the minimum, the

  1. Slope of the operating line in stripping section decreases
  2. Number of plates decreases very slowly first and then more and more rapidly
  3. Total cost first decreases and then increases
  4. Liquid flow increases while the vapor flow decreases for a system

Correct answer: (C)
Total cost first decreases and then increases

67.As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages

  1. Increase
  2. Decrease
  3. Remain unchanged
  4. Can either increase or decrease, depends on the system

Correct answer: (B)
Decrease

68.At _________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation.

  1. Operating
  2. Total
  3. Minimum
  4. Maximum permissible

Correct answer: (B)
Total

69.At 750°K and 1 atm, the approximate value of Schmidt number for air is

  1. 0.01
  2. 0.1
  3. 1
  4. 10

Correct answer: (B)
0.1

70.At a fixed pressure, the humidity depends upon the partial pressure of vapor in the mixture. Humidity of a vapour free gas is _________ percent.

  1. 100
  2. 0
  3. 50
  4. Between 0 and 100

Correct answer: (B)
0

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