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Chemical Engineering :: Mass Transfer

  1. The McCabe Δ L law states that the

  2. A.
    molar heats of vaporisation of components are nearly equal.
    B.
    linear crystal growth rate depends on the degree of supersaturation.
    C.
    linear crystal growth rate does not depend on the crystal size.
    D.
    linear crystal growth rate depends on the crystal size.

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  3. Bollman extractor

  4. A.
    is a static bed leaching equipment.
    B.
    is used for extraction of oil from oilseed.
    C.
    is a centrifugal extractor.
    D.
    employs only counter-current extraction.

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  5. The relation, Sc = Pr = 1, is valid, when the mechanism of __________ ansfer is same.

  6. A.
    heat and mass
    B.
    mass and momentum
    C.
    heat and momentum
    D.
    heat, momentum and mass

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  7. A coalescer in a mixer-settler liquid-liquid extraction coloumn

  8. A.
    comprises of thin bed of substances of extended surface having high porosity.
    B.
    helps in increasing the bubble size entering the settler.
    C.
    helps in increasing the settling rate of the bubbles.
    D.
    all 'a', 'b', & 'c'.

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  9. For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will

  10. A.
    increase
    B.
    decrease
    C.
    remain same
    D.
    data insufficient, can't be predicted

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  11. Pick out the correct statement.

  12. A.
    Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non-ideal binary system by distillation.
    B.
    A sharp decrease in pressure drop is an indication of flooding in a distillation coloumn.
    C.
    Solvent used in extractive distillation should be of high volatility.
    D.
    Flash distillation is suitable for separating components which have very close boiling temperature.

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  13. When the liquid phase and vapour phase of a binary system obeys Raoult's and Dalton's law respectively, the relative volatility is the ratio of

  14. A.
    vapour pressure of component A to that of component B.
    B.
    vapour pressure of component A to the total pressure.
    C.
    vapour pressure of component A to the partial pressure of A.
    D.
    partial pressure of component A to the total pressure.

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  15. The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called

  16. A.
    decoction
    B.
    percolation
    C.
    elutriation or elution
    D.
    none of these

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  17. In the constant rate period of the rate of drying curve for batch drying,

  18. A.
    cracks develop on the surface of the solid.
    B.
    rate of drying decreases abruptly.
    C.
    surface evaporation of unbound moisture occurs.
    D.
    none of these.

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  19. It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%).

  20. A.
    15 min
    B.
    51 min
    C.
    71 min
    D.
    94 min

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