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Chemical Engineering :: Mass Transfer

  1. Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when

  2. A.
    extracting solvent is cheaply & abundantly available.
    B.
    one of the liquid components is heat sensitive.
    C.
    viscosity of liquid components is very high.
    D.
    one of the liquid components has very high affinity towards the solvent.

  3. Inside the distillation column, the

  4. A.
    driving force for the vapour flow is the pressure drop.
    B.
    liquids are not always at their bubble points.
    C.
    pressure increases gradually from bottom to the top of the column.
    D.
    none of these

  5. Diffusivity in concentrated solutions differs from that in dilute solutions, because of the changes in

  6. A.
    viscosity with concentration.
    B.
    degree of ideality of the solution.
    C.
    both (a) and (b).
    D.
    neither (a) nor (b).

  7. Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate.

  8. A.
    increases
    B.
    decreases
    C.
    does not affect
    D.
    exponentially increases

  9. Which of the following is not a continuous drier ?

  10. A.
    Drum drier
    B.
    Spray drier
    C.
    Tunnel drier
    D.
    Tray drier

  11. Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is

  12. A.
    insoluble in the liquid
    B.
    soluble in the liquid
    C.
    non-ideal in nature
    D.
    at a fixed temperature

  13. __________ is the temperature at which a gas-vapor mixture becomes saturated, when cooled at constant total pressure out of contact with a liquid.

  14. A.
    Dew point
    B.
    Bubble point
    C.
    Dry bulb temperature
    D.
    Wet bulb temperature

  15. Rate of leaching increases with increasing

  16. A.
    temperature
    B.
    viscosity of solvent
    C.
    pressure
    D.
    size of the solid

  17. An azeotropic mixture is a __________ mixture.

  18. A.
    binary
    B.
    ternary
    C.
    constant boiling point
    D.
    none of these

  19. Pick out the wrong statement.

  20. A.
    In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed.
    B.
    In small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency.
    C.
    For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 x 10-2m/s. Then the average mass transfer co-efficient for the plate is 2 x 10-2m/s.
    D.
    The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity.