Chemical Engineering Mass Transfer Short Questions - Set 20 - ObjectiveBooks

Chemical Engineering Mass Transfer Short Questions - Set 20

Practice Test: Question Set - 20

1. During constant rate drying period, vaporization rate per unit drying surface area
    (A) Decreases with time
    (B) Increases with time
    (C) Does not change with time
    (D) Does not affect the moisture content of the wet solid

2. A coalescer in a mixer-settler liquid-liquid extraction column
    (A) Comprises of thin bed of substances of extended surface having high porosity
    (B) Helps in increasing the bubble size entering the settler
    (C) Helps in increasing the settling rate of the bubbles
    (D) All 'a', 'b', & 'c'

3. Which of the following T-H diagram is valid for dehumidification operation?
Mass Transfer - Set 20, Question No. 03

4. In which of the following unit operations, the selectivity is an important parameter?
    (A) Distillation
    (B) Solvent extraction
    (C) Absorption
    (D) None of these

5. Flash distillation is suitable for separating the constituents of a binary system, which
    (A) Form minimum boiling azeotrope
    (B) Have very wide boiling points
    (C) Have very close boiling points
    (D) Form constant boiling azeotrope

6. In case of an unsaturated mixture of gas and vapor, the percentage saturation is __________ its relative saturation.
    (A) Lower than
    (B) Higher than
    (C) Equal to
    (D) Either (a) or (b), depends on the mixture composition

7. At __________ reflux, theoretical number of plates in a distillation column is calculated using Fenske-Underwood equation.
    (A) Operating
    (B) Total
    (C) Minimum
    (D) Maximum permissible

8. Pick out the correct statement.
    (A) The slope of the stripping line is always less than unity
    (B) For a given separation in a binary distillation column, with increase in reflux ratio (above the minimum reflux ratio), the fixed cost of the distillation column first increases and then decreases
    (C) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux
    (D) Kremser-Brown-Souder's equation is used to calculate the efficiency of a plate tower

9. In physical terms, Schmidt number means
    (A) Thermal diffusivity/mass diffusivity
    (B) Thermal diffusivity/momentum diffusivity
    (C) Momentum diffusivity/mass diffusivity
    (D) Mass diffusivity/thermal diffusivity

10. Unit operation involved in the prilling of urea is
    (A) Evaporation
    (B) Drying
    (C) Crystallization
    (D) Both (b) and (c)

11. Degree of freedom for leaching and solvent extraction process is
    (A) 0
    (B) 1
    (C) 2
    (D) 3

12. With increase in temperature, the solubility of gases in liquids, at fixed pressure
    (A) Increases
    (B) Decreases
    (C) Remain same
    (D) Either (a) or (b), depends on the system

13. The equipment used in the extraction of highly corrosive radioactive liquids is
    (A) Pulse column
    (B) Spray column
    (C) Mixer settler
    (D) Baffle tower

14. Tea percolation employs
    (A) Liquid-liquid extraction
    (B) Leaching
    (C) Absorption
    (D) None of these

15. When the solvent dissolves very little of solute, then
    (A) Solvent of low latent heat of vaporization should be used
    (B) Solvent of low freezing point should be used
    (C) Large quantity of solvent is required to extract the solute
    (D) Very small quantity of solvent is required

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