Mass Transfer

151.Fenske equation for determining the minimum number of theoretical stages in distillation column holds good, when the

  1. Relative volatility is reasonably constant
  2. Mixture (to be separated) shows negative deviation from ideality
  3. Mixture (to be separated) shows positive deviation from ideality
  4. Multi-component distillation is involved

Correct answer: (A)
Relative volatility is reasonably constant

152.Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for

  1. Constant molal overflow
  2. Total reflux
  3. Constant relative volatility
  4. All (A), (B) and (C)

Correct answer: (D)
All (A), (B) and (C)

153.Flash distillation is

  1. Same as differential distillation
  2. Used for multi-component systems like crude refining
  3. Same as simple distillation
  4. Most useful for handling binary systems

Correct answer: (B)
Used for multi-component systems like crude refining

154.Flash distillation is suitable for separating the constituents of a binary system, which

  1. Form minimum boiling azeotrope
  2. Have very wide boiling points
  3. Have very close boiling points
  4. Form constant boiling azeotrope

Correct answer: (B)
Have very wide boiling points

155.Flash distillation is suitable for the separation of components

  1. Having very close boiling points
  2. Which form maximum boiling azeotrope
  3. Having very wide boiling points
  4. Which form minimum boiling azeotrope

Correct answer: (C)
Having very wide boiling points

156.Flights in a rotary dryer are provided to

  1. Lift and shower the solids thus exposing it thoroughly to the drying action of the gas
  2. Reduce the residence time of solid
  3. Increase the residence time of the solid
  4. None of these

Correct answer: (A)
Lift and shower the solids thus exposing it thoroughly to the drying action of the gas

157.Flooding in a column results due to

  1. High pressure drop
  2. Low pressure drop
  3. Low velocity of the liquid
  4. High temperature

Correct answer: (A)
High pressure drop

158.Flooding in a distillation column is detected by a sharp

  1. Increase in Murphree plate efficiency
  2. Decrease in pressure drop
  3. Decrease in liquid hold up in the column
  4. Increase in pressure drop

Correct answer: (D)
Increase in pressure drop

159.Flooding in a vapor-liquid contacting equipment occurs in a tray, when the pressure drop through a tray is _________ the liquid head available in the downcomer.

  1. Less than
  2. More than
  3. Same as
  4. Very much less

Correct answer: (B)
More than

160.Flooding results in

  1. High tray efficiency
  2. Low tray efficiency
  3. High gas velocity
  4. Good contact between the fluids

Correct answer: (B)
Low tray efficiency

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