Mechanical Operations(Chemical Engineering ) Questions and Answers

Question 1. During agitation of liquids, the
  1.    Froude number is independent for the curves between power number and Reynolds number in baffled system
  2.    Power number becomes independent of impellers Reynolds number at high Reynolds number, but is dependent on the geometry of the impeller
  3.    Froude number is used to account for the effect of surface (e.g., the centre vortex) on the power number
  4.    All of the above
Explanation:-
Answer: Option D. -> All of the above
Question 2. According to Bond crushing law, the work required to form particle of size 'D' from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively).
  1.    (S/V)p
  2.    √(S/V)p
  3.    (S/V)²p
  4.    (S/V)f
Explanation:-
Answer: Option B. -> √(S/V)p
Question 3. The distribution given by microscopic analysis of powder is
  1.    Number
  2.    Length
  3.    Area
  4.    Volume
Explanation:-
Answer: Option A. -> Number
Question 4. Angle of nip of the crushing rolls does not depend upon the
  1.    Diameter of the rolls
  2.    Speed of the rolls
  3.    Product size
  4.    Feed size
Explanation:-
Answer: Option B. -> Speed of the rolls
Question 5. Filter aids like asbestos, kieselguhr, diatomaceous earth etc. are used to increase the porosity of the final filter cake & reducing the cake resistance during filtration. Filter aid is
  1.    Added to the feed slurry
  2.    Precoated on the filter medium prior to filtration
  3.    Separated from the cake by dissolving solids or by burning it off
  4.    All of the above
Explanation:-
Answer: Option D. -> All of the above
Question 6. Which of the following gives the work required for size reduction of coal to -200 mesh in a ball mill most accurately ?
  1.    Rittinger's law
  2.    Kick's law
  3.    Bond's law
  4.    None of these
Explanation:-
Answer: Option A. -> Rittinger's law
Question 7. Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is
  1.    0.5
  2.    1
  3.    √2
  4.    √3
Explanation:-
Answer: Option B. -> 1
Question 8. Which of the following is not categorised as a "mechanical operation"?
  1.    Agitation
  2.    Filtration
  3.    Size enlargement
  4.    Humidification
Explanation:-
Answer: Option D. -> Humidification
Question 9. Traces of solids are removed from, liquid in a
  1.    Classifier
  2.    Clarifier
  3.    Sparkler filter
  4.    Rotary vacuum filter
Explanation:-
Answer: Option B. -> Clarifier
Question 10. __________ mills are termed as disintegrators.
  1.    Cage
  2.    Compartment
  3.    Pebble
  4.    All of the above
Explanation:-
Answer: Option A. -> Cage
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