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Chemical Engineering :: Mass Transfer

  1. The operating cost of a distillation column at minimum reflux ratio is

  2. A.
    minimum
    B.
    maximum
    C.
    infinite
    D.
    zero

  3. The reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. The reflux ratio is

  4. A.
    2
    B.
    0.5
    C.
    50
    D.
    150

  5. Molecular diffusivity of a liquid

  6. A.
    increases with temperature.
    B.
    decreases with temperature.
    C.
    may increase or decrease with temperature.
    D.
    is independent of temperature.

  7. The wet and 'dry bulb temperature for a vapour-gas mixture are 25°C and 30°C respectively. If the mixture is heated to 45°C at constant pressure, the wet bulb temperature will be __________ °C.

  8. A.
    25
    B.
    > 25
    C.
    < 25
    D.
    - 25

  9. Henry's law states that the

  10. A.
    partial pressure of a component over a solution is proportional to its mole fraction in the liquid.
    B.
    partial pressure of a component over a solution is proportional to the mole fraction in the vapour.
    C.
    vapour pressure is equal to the product of the mole fraction and total pressure.
    D.
    partial pressure is equal to the product of the mole fraction and total pressure.

  11. Ammonia present in the coke oven gas is removed by washing with

  12. A.
    caustic solution
    B.
    dilute ammoniacal liquor
    C.
    dilute HCl
    D.
    ethanolamine

  13. With increase in temperature, the leaching rate increases due to

  14. A.
    decreased liquid viscosity
    B.
    increased diffusivity
    C.
    both (a) and (b)
    D.
    neither (a) nor (b)

  15. Which of the following processes is not an example of adsorption applied to gaseous separations ?

  16. A.
    Recovery of valuable solvent vapors from dilute mixture with air and other gases.
    B.
    Dehumidification of air and gas.
    C.
    Removal of objectionable odour and impurities from industrial gases.
    D.
    Decolouration of yellow glycerene.

  17. The critical moisture content in case of drying indicates the __________ rate period.

  18. A.
    beginning of falling
    B.
    beginning of constant
    C.
    end of falling
    D.
    none of these

  19. Pick out the wrong statement

  20. A.
    A horizontal line on the humidity chart indicates the temperature changes at constant molal humidity.
    B.
    When water is cooled from 80 to 70°C by exposure to the air with a wet bulb temperature of 60°C, then both the approach & the range would be 10°C.
    C.
    For unsaturated air-water vapor mixture at atmospheric conditions, the wet bulb temperature & adiabatic cooling lines are the same.
    D.
    Relative saturation of unsaturated mixture of water vapor & air can not be increased by either reducing the mixture temperature or by increasing the total pressure.