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Chemical Engineering :: Mass Transfer

  1. Relative humidity is the ratio of the

  2. A.
    partial pressure of the vapour to the vapour pressure of the liquid at room temperature.
    B.
    partial pressure of the vapour to the vapour pressure of the liquid at gas temperature.
    C.
    actual humidity to saturation humidity.
    D.
    none of these

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  3. In batch distillation with constant reflux, overhead product composition __________ with time.

  4. A.
    increases
    B.
    decreases
    C.
    does not vary
    D.
    may increase on decrease, depends on the system.

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  5. Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined by the measurement of the __________ of a fibre.

  6. A.
    electrical resistance
    B.
    thermal conductivity
    C.
    strength
    D.
    none of these.

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  7. Heat in BTU necessary to increase the temperature of 1 lb of gas and its accompanying vapour by 1°F is called the

  8. A.
    latent heat
    B.
    humid heat
    C.
    specific heat
    D.
    sensible heat

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  9. To increase the absorption factor, (where, G = gas flow rate, S = solvent flow rate)

  10. A.
    increase both 'G' and 'S'.
    B.
    decrease both 'G' and 'S'.
    C.
    increase 'S' and decrease 'G'.
    D.
    increase 'G' and decrease 'S'

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  11. Dew point of a gas-vapour mixture

  12. A.
    increases with temperature rise.
    B.
    decreases with temperature rise.
    C.
    decreases with decrease in pressure.
    D.
    increases with increase in pressure.

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  13. In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG __________ the absorption factor.

  14. A.
    increases with increase in
    B.
    is one at unity value of
    C.
    both (a) and (b)
    D.
    neither (a) nor (b)

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  15. Which of the following plays an important role in problems of simultaneous heat and mass transfer ?

  16. A.
    Lewis number
    B.
    Schmidt number
    C.
    Prandtl number
    D.
    Sherwood number

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  17. In case of an absorber, the operating

  18. A.
    line always lies above the equilibrium curve.
    B.
    line always lies below the equilibrium curve.
    C.
    line can be either above or below the equilibrium curve.
    D.
    velocity is more than the loading velocity.

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  19. As the reflux ratio in a distillation coloumn is increased from the minimum, the

  20. A.
    slope of the operating line in stripping section decreases.
    B.
    number of plates decreases very slowly first and then more and more rapidly.
    C.
    total cost first decreases and then increases.
    D.
    liquid flow increases while the vapor flow decreases for a system.

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