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Chemical Engineering :: Mechanical Operations

  1. Width and speed of a conveyor belt depends upon the __________ of the material.

  2. A.
    lump size
    B.
    bulk density
    C.
    both (a) & (b)
    D.
    neither (a) nor (b)

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  3. Higher is the mesh number, smaller will be the aperture size of the screen. It means that the aperture size of a 200 mesh screen will be smaller than that of 20 mesh screen. This is valid for

  4. A.
    British standard screens.
    B.
    German standard screens (DIN 1171) etc.
    C.
    American standard screens (ASTM and Tyler standard screens).
    D.
    all (a), (b) and (c).

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  5. Pick out the wrong statement.

  6. A.
    Cummulative analysis for determining surface area is preferred over differential analysis, because of the assumption that "all particles in a simple fraction equal in size" is not needed for cummulative anslysis unlike differential anlaysis.
    B.
    A gate diagram is a plot of cummulative percent by weight undersize vs. the reciprocal of diameter, in which the area beneath the curve represents the surface.
    C.
    Capacity of crusher in choke feeding is increased.
    D.
    Rolling of pebbles/balls from top to bottom of the heap in tumbling mills is called 'cascading and throwing of the balls through the air to the toe of the heap is called 'cataracting'.

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  7. Which of the following size reduction equipments employs mainly attrition for ultrafine grinding ?

  8. A.
    Jet mills
    B.
    Fluid energy mill
    C.
    Micronizer
    D.
    all (a), (b) and (c)

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  9. Tank filter (e.g., Nutsch filter) is

  10. A.
    a high pressure filter.
    B.
    a continuous filter.
    C.
    used for small scale filtration work.
    D.
    a leaf filter.

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  11. In bag filters, filter fabrics are never made of

  12. A.
    metallic wire woven mesh
    B.
    polyester fibres
    C.
    cotton fibres
    D.
    nylon fibres

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  13. Use of 'grinding aids' is done in __________ grinding.

  14. A.
    dry
    B.
    wet
    C.
    ultrafine
    D.
    intermediate

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  15. Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter)

  16. A.
    0.5 D
    B.
    D
    C.
    1.5 D
    D.
    2 D

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  17. Which of the following is the most suitable filter for separation of abrasive solids suspended in a corrosive liquid ?

  18. A.
    Sand bed filter
    B.
    Plate and frame filter press
    C.
    Vacuum filter
    D.
    Batch basket centrifuge.

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  19. All resistances during washing of cake

  20. A.
    increases
    B.
    decreases
    C.
    remain constant
    D.
    none of these

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