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Chemical Engineering :: Mass Transfer

  1. Perforated plate towers are unique for solvent extraction because, they provide

  2. A.
    higher contact area.
    B.
    better contact of the phase.
    C.
    repeated coalescence & redispersion of the drop phase.
    D.
    none of these.

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  3. In case of absorption & stripping, the interface of the liquid & gas phases are present in equilibrium, when the diffusional resistance of __________ is zero.

  4. A.
    interface
    B.
    gas phase
    C.
    liquid phase
    D.
    all 'a', 'b' & 'c'

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  5. Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations.

  6. A.
    Sherwood number in mass transfer is analogous to Nusselt number in heat transfer.
    B.
    Prandtl number in heat transfer is analogous to Schmidt number in mass transfer.
    C.
    Reynolds number in mass transfer is analogous to Grashoff number in heat transfer.
    D.
    Reynolds number remains the same in both heat and mass transfer.

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  7. The individual mass transfer co-efficients (moles/m2 . s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling ?

  8. A.
    liquid side
    B.
    gas side
    C.
    interfacial
    D.
    both liquid and gas side

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  9. Pore size of the molecular seive 5A is __________ mm.

  10. A.
    5
    B.
    0.5
    C.
    0.05
    D.
    50

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  11. Swenson-Walker crystalliser is a __________ unit

  12. A.
    continuous
    B.
    batch
    C.
    semi-batch
    D.
    cooling (adiabatic)-cum-evaporation

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  13. According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the coloumn.

  14. A.
    5
    B.
    9
    C.
    12
    D.
    28

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  15. Absorption (liquid-gas system) with evolution of heat as compared to isothermal absorption results in

  16. A.
    decreased solute solubility.
    B.
    large minimum liquid to gas (L/G) ratio.
    C.
    large number of trays.
    D.
    all (a), (b) and (c).

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  17. With increase in temperature, the mutual solubility of two liquids

  18. A.
    increases
    B.
    decreases
    C.
    remains unchanged
    D.
    decreases exponentially

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  19. Pick out the wrong statement.

  20. A.
    In solvent extraction, the distribution co-efficient should be as large as possible for solvent economy.
    B.
    With increase in pressure, the solubility of gases in solvent increases at a fixed temperature.
    C.
    Decrease in Murphree plate efficiency is an indication of entrainment in distillation coloumn.
    D.
    The capacity of a distillation coloumn is maximum at total reflux.

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