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Chemical Engineering :: Mechanical Operations

  1. Ultra centrifuges are used for the separation of __________ solid particles.

  2. A.
    coarse
    B.
    fine
    C.
    colloidal
    D.
    dissolved

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  3. Specific surface area is the surface area of a unit __________ of materials.

  4. A.
    weight
    B.
    volume
    C.
    either (a) or (b)
    D.
    neither (a) nor (b)

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  5. A. __________ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end.

  6. A.
    compartment
    B.
    tube
    C.
    rod
    D.
    pebble.

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  7. The constants (Kb, Kr and Kk) used in the laws of crushing (i.e., Bond's law, Rittinger's law and Kick's law) depend upon the

  8. A.
    feed material.
    B.
    type of crushing machine.
    C.
    both (a) & (b).
    D.
    neither (a) nor (b).

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  9. Size reduction does not occur due to compression in case of

  10. A.
    rod mills
    B.
    gyratory crushers
    C.
    jaw crushers
    D.
    smooth roll crushers

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  11. According to Taggart's rule for selecting between a gyratory crusher and a jaw crusher; the later should be used, if the hourly tonnage to be crushed divided by the square of the gape expressed in cm is less than

  12. A.
    0.00184
    B.
    0.0184
    C.
    0.184
    D.
    1.84

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  13. Which of the following represents the plot of filtrate volume versus time for constant pressure filtration ?

  14. A.
    Parabola
    B.
    Straight line
    C.
    Hyperbola
    D.
    Exponential curve

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  15. Driving force in case of filtration by a centrifuge is the

  16. A.
    speed of the centrifuge.
    B.
    centrifugal pressure exerted by the liquid.
    C.
    narrow diameter of the vessel.
    D.
    formation of highly porous cake.

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  17. Rod mills employed for grinding

  18. A.
    employ a steel shell having L/D ratio of 1.5 to 3.0.
    B.
    is useful for handling sticky materials.
    C.
    employ steel rods of 2-12 cms diameter extending over full length of the mill.
    D.
    all 'a', 'b' & 'c'.

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  19. Production rate __________ with increased fineness, with a given energy input to the size reduction machine.

  20. A.
    decreases
    B.
    increases
    C.
    remains unchanged
    D.
    may increase or decrease; depends on the machine

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