Mass Transfer(Chemical Engineering ) Questions and Answers

Question 1. Moisture contained by a substance in excess of the equilibrium moisture is called the __________ moisture.
  1.    Unbound
  2.    Free
  3.    Critical
  4.    Bound
Explanation:-
Answer: Option B. -> Free
Question 2. Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the __________ moisture.
  1.    Unbound
  2.    Critical
  3.    Free
  4.    Bound
Explanation:-
Answer: Option A. -> Unbound
Question 3. Diameter of raschig rings used in packed tower in industry is normally around __________ inches.
  1.    2
  2.    8
  3.    12
  4.    18
Explanation:-
Answer: Option A. -> 2
Question 4. Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture.
  1.    Bound
  2.    Unbound
  3.    Critical
  4.    None of these
Explanation:-
Answer: Option A. -> Bound
Question 5. Moisture content of a substance when at equilibrium with a given partial pressure of the vapour is called the __________ moisture.
  1.    Free
  2.    Unbound
  3.    Equilibrium
  4.    Bound
Explanation:-
Answer: Option C. -> Equilibrium
Question 6. Pick out the wrong statement.
  1.    In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed
  2.    In small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency
  3.    For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 x 10⁻²m/s. Then the average mass transfer co-efficient for the plate is
  4.    The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity
Explanation:-
Answer: Option C. -> For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 x 10⁻²m/s. Then the average mass transfer co-efficient for the plate is
Question 7. The term "cooling range" in a cooling tower refers to the difference in the temperature of
  1.    Cold water leaving the tower and the wet bulb temperature of the surrounding air
  2.    Hot water entering the tower and the wet bulb temperature of the surrounding air
  3.    Hot water entering the tower and the cooled water leaving the tower
  4.    None of these
Explanation:-
Answer: Option C. -> Hot water entering the tower and the cooled water leaving the tower
Question 8. Fenske equation determines the
  1.    Maximum number of ideal plates
  2.    Height of the distillation column
  3.    Minimum number of theoretical plates
  4.    Optimum reflux ratio
Explanation:-
Answer: Option C. -> Minimum number of theoretical plates
Question 9. Mass transfer co-efficient is defined as
  1.    Flux = Co-efficient/concentration difference
  2.    Co-efficient = Flux/concentration difference
  3.    Flux=concentration difference/co-effi-cient
  4.    None of these
Explanation:-
Answer: Option B. -> Co-efficient = Flux/concentration difference
Question 10. __________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower.
  1.    Sherwood
  2.    Stanton
  3.    Lewis
  4.    Peclet
Explanation:-
Answer: Option C. -> Lewis
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