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Chemical Engineering :: Mechanical Operations

  1. For Indian standard (IS) screens, the mesh number is equal to its aperture size expressed to the nearest deca-micron (0.01 mm). Aperture width of IS screen of mesh number 50 will be approximately __________ microns.

  2. A.
    5
    B.
    50
    C.
    500
    D.
    5000

  3. __________ mills are termed as disintegrators.

  4. A.
    Cage
    B.
    Compartment
    C.
    Pebble
    D.
    All tumbling

  5. Supporting legs of a plate and frame filter is normally made of

  6. A.
    stainless steel
    B.
    cast iron
    C.
    high speed steel
    D.
    wooden plank

  7. The cummulative mass fraction of particles smaller than size dj for a collection of Ni particles of diameter di and mass mi (i = 1, 2, 3, ...... ∞) is given by


  8. Wet grinding in a revolving mill __________ as compared to dry grinding.

  9. A.
    gives less wear on chamber walls
    B.
    requires more energy
    C.
    increases capacity
    D.
    complicates handling of the product

  10. The grinding in a hammer crusher takes place due to the

  11. A.
    attrition
    B.
    impact
    C.
    both (a) & (b)
    D.
    neither (a) nor (b)

  12. A compressible cake has the

  13. A.
    maximum porosity at the upstream side.
    B.
    maximum porosity at the filter medium.
    C.
    same porosity throughout the cake thickness.
    D.
    none of these.

  14. Which of the following is not used as a filter medium in case of corrosive liquids ?

  15. A.
    Nylon
    B.
    Glass cloth
    C.
    Metal cloth of monel or stainless steel
    D.
    Cotton fabric

  16. In ball mill operation, the feed size (Df in meters) and the ball diameter (Db in metres) are related as ( where, K = grindability constant (varying from 0.9 to 1.4 in increasing order of hard ness))

  17. A.
    Db2 = K.Df
    B.
    Db = K.Df
    C.
    Db3 = K.Df
    D.
    Db2 = K.Df2

  18. Pine oil and cresylic acid are used as __________ in the froth floatation process.

  19. A.
    frother
    B.
    collector
    C.
    depressor
    D.
    conditioner