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Chemical Engineering :: Mass Transfer

  1. Which one of the following devices is not used for both the absorption as well as the liquid-liquid extraction processes ?

  2. A.
    Packed towers
    B.
    Plate towers
    C.
    Spray towers
    D.
    Wetted wall columns

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  3. The temperature of water cooled in cooling tower is always __________ temperature of entering air.

  4. A.
    more than the wet bulb
    B.
    less than the wet bulb
    C.
    equal to the wet bulb
    D.
    equal to the dry bulb

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  5. Which of the following processes is followed by unsaturated air (with dry bulb temperature 12°C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40°C?

  6. A.
    Humidification only
    B.
    Heating only
    C.
    Both heating and humidification
    D.
    Evaporative cooling

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  7. Mass transfer co-efficient is directly proportional to DAB according to the __________ theory.

  8. A.
    film
    B.
    penetration
    C.
    surface-renewal
    D.
    none of these

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  9. The relative volatility of a binary mixture at constant temperature __________ the total pressure.

  10. A.
    decreases with increase in
    B.
    increases with increase in
    C.
    is independent of
    D.
    none of these

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  11. Tower diameter may be decreased by

  12. A.
    using higher reflux ratio.
    B.
    use of increased tray spacing.
    C.
    increasing the liquid flow rate.
    D.
    increasing the vapour flow rate.

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  13. Rayleigh's equation applies to __________ distillation.

  14. A.
    continuous
    B.
    steam
    C.
    differential
    D.
    flash

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  15. Steady state equimolal counter diffusion is encountered in

  16. A.
    separation of a binary mixture by distillation.
    B.
    absorption of NH3 from air by water.
    C.
    all liquid-liquid diffusion systems.
    D.
    all liquid-solid diffusion systems.

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  17. Which of the following is considered equivalent to one theoretical stage in Mc-Cabe Thiele's method ?

  18. A.
    Partial condenser
    B.
    Total condenser
    C.
    Reboiler
    D.
    Both (b) and (c)

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  19. Polar organic compounds are normally used as separating agents for the azeotropic and extractive distillation. Which of the following is the most important factor to be considered for the choice of the separating agent for extractive distillation ?

  20. A.
    Cost
    B.
    Availability
    C.
    Toxicity
    D.
    Selectivity

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