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Chemical Engineering :: Mechanical Operations

  1. Separation of solid particles based on their densities is called

  2. A.
    sizing
    B.
    sorting
    C.
    clarification
    D.
    dispersion

  3. Activators are those chemicals which help buoying up one mineral in preference to the other in the froth floatation process. Which of the following is an activator?

  4. A.
    Cresylic acid
    B.
    Copper sulphate
    C.
    Calcium carbonate
    D.
    Sodium carbonate

  5. __________ are mixed using ribbon blenders.

  6. A.
    Lumpy solids and low viscosity liquids
    B.
    Dry powders
    C.
    High viscosity liquids
    D.
    Thick pastes

  7. During agitation of liquids, the

  8. A.
    Froude number is independent for the curves between power number and Reynolds number in baffled system.
    B.
    Power number becomes independent of impellers Reynolds number at high Reynolds number, but is dependent on the geometry of the impeller.
    C.
    Froude number is used to account for the effect of surface (e.g., the centre vortex) on the power number.
    D.
    all (a), (b) and (c).

  9. For crushing of solids, the Rittinger's law states that the work required for crushing is proportional to

  10. A.
    the new surface created.
    B.
    the size reduction ratio.
    C.
    the change in volume due to crushing.
    D.
    none of these.

  11. In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the __________ crushing.

  12. A.
    secondary
    B.
    fine
    C.
    primary
    D.
    ultrafine

  13. As per Taggart's formula, the capacity (kg/hr) of Jaw & Gyratory crushers (for gapes of 10 to 60 cms) is equal to (where, L = Length of feed opening, cms S = Maximum width of discharge opening, cms )

  14. A.
    LS
    B.
    93 LS
    C.
    250 LS
    D.
    LS

  15. The process by which fine solids is removed from liquids is termed as

  16. A.
    decantation
    B.
    flocculation
    C.
    sedimentation
    D.
    classification

  17. Which of the following crushing laws is most accurately applicable to the fine grinding of materials ?

  18. A.
    Bond's crushing law
    B.
    Kick's law
    C.
    Rittinger's law
    D.
    None of these.

  19. Shell and leaf filter as compared to plate and frame filter

  20. A.
    entails less labor cost.
    B.
    facilitates filtration under higher pressure.
    C.
    provides more effective washing.
    D.
    all (a), (b) & (c)