Mass Transfer Questions MCQs

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  2. Chemical Engineering
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mass transfer Questions

Total Questions : 656

Page 1 of 33 pages
Question 1. A coalescer in a mixer-settler liquid-liquid extraction coloumn
  1.    Comprises of thin bed of substances of extended surface having high porosity
  2.    Helps in increasing the bubble size entering the settler
  3.    Helps in increasing the settling rate of the bubbles
  4.    All of the above
Answer: Option D
Question 2. Tower diameter may be decreased by
  1.    Using higher reflux ratio
  2.    Use of increased tray spacing
  3.    Increasing the liquid flow rate
  4.    Increasing the vapour flow rate
Answer: Option B
Question 3. 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
Answer: Option C
Question 4. Make up water is required in a cooling tower to replace the water lost by
  1.    Evaporation
  2.    Drift
  3.    Blowdown and leakage
  4.    All of the above
Answer: Option D
Question 5. In a moderately sized packed absorption tower, channeling (which is most severe with stacked packings) can be minimised by taking the ratio of tower diameter to packing diameter
  1.    > 4 :1
  2.    < 8 : 1
  3.    > 8:1
  4.    < 6:1
Answer: Option C
Question 6. In an absorber, HETP does not vary with the
  1.    Flow rate of liquid
  2.    Flow rate of gas
  3.    Type and size of packing
  4.    None of these
Answer: Option D
Question 7. Use of natural draft cooling tower is practised, when the air has low
  1.    Humidity
  2.    Temperature
  3.    Both A & B
  4.    Neither A nor B
Answer: Option C
Question 8. Raoult's law applies to the
  1.    All liquid solutions
  2.    Non-ideal solution only
  3.    Non-volatile solute
  4.    Solvents
Answer: Option D
Question 9. The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is
  1.    +ve
  2.    -ve
  3.    Zero
  4.    None of these
Answer: Option A
Question 10. Which of the following can be calculated theoretically using steam table and Dalton's law of partial pressure; if the relative humidity and dry bulb temperature of moist air is known?
  1.    Dew point
  2.    Humidity ratio
  3.    Wet bulb temperature
  4.    None of these
Answer: Option C
Question 11. In distillation columns, the number of bubble caps per tray primarily depends upon the
  1.    Allowable liquid velocity
  2.    Allowable gas velocity
  3.    Allowable gas and liquid velocities
  4.    Feed composition
Answer: Option C
Question 12. Gaseous diffusivity at atmospheric pressure is of the order of __________ cm²/second.
  1.    1
  2.    1 to 5
  3.    5 to 10
  4.    > 10
Answer: Option A
Question 13. According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity)
  1.    D
  2.    D2
  3.    D0.5
  4.    1/D
Answer: Option A
Question 14. For gas absorption, low viscosity solvents are preferred, because of their
  1.    Better flow characteristics
  2.    Low pumping pressure drop
  3.    Rapid absorption rates
  4.    All of the above
Answer: Option D
Question 15. The change in enthalpy, when a unit quantity of gas is absorbed by relatively large quantity of adsorbent (on which a definite concentration of the adsorbed gas already exists) is termed as the
  1.    Differential heat of adsorption
  2.    Heat of wetting
  3.    Integral heat of adsorption
  4.    None of these
Answer: Option A
Question 16. Pick out the wrong statement:
  1.    Change in barometric pressure does not affect the relative humidity
  2.    In case of a packed tower, the operating velocity is about half of the flooding velocity, generally
  3.    'Elution' means the desorption of the adsorbed solute by a solvent
  4.    The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity
Answer: Option D
Question 17. On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapor feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in
  1.    Greater degree of separation with a fixed number of trays
  2.    Increased reboiler load
  3.    Increased reflux ratio
  4.    None of these
Answer: Option C
Question 18. Steam distillation is not recommended to be used, if the
  1.    Azeotropic mixture is to be separated and the final product is miscible with water
  2.    Liquids decompose, if distilled directly at atmospheric pressure
  3.    Material can not be distilled by indirect heating even under low pressure, because of the high boiling temperature
  4.    Material to be distilled is thermally unstable or has the tendency to react with other components associated with it, at the boiling temperature
Answer: Option A
Question 19. Chemisorption compared to physical absorption has
  1.    Lower adsorption rate
  2.    Lower capacity of the solvent for the solute gas
  3.    Increased utilisation of stagnant zones of the liquid phase
  4.    None of these
Answer: Option C
Question 20. 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
Answer: Option B

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