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Chemical Engineering :: Mass Transfer

  1. The cooling effect in a cooling tower can not be increased by

  2. A.
    increasing the air velocity over the wet surfaces.
    B.
    reducing the humidity of entering air.
    C.
    lowering the barometric pressure.
    D.
    none of these.

  3. The value of NA/(NA + NB) for steady state molecular diffusion of gas 'A' through non-diffusing gas 'B' is

  4. A.
    1
    B.
    C.
    0.5
    D.
    2

  5. The humid volume may be increased by increasing the

  6. A.
    temperature at constant humidity.
    B.
    humidity at constant temperature.
    C.
    both (a) and (b).
    D.
    neither (a) nor (b).

  7. Pick out the wrong statement

  8. A.
    Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure substance.
    B.
    In case of gas absorption, HETP is equal to HTU, when both the operating line & the equilibrium lines are parallel.
    C.
    Hatta number is important in case of gas absorption with chemical reaction.
    D.
    In actual practice, absorption is an en-dothermic process, while stripping is an exothermic process.

  9. When the mixture to be distilled has a very high boiling point and the product material is heat sensitive, the separation technique to be used is __________ distillation.

  10. A.
    continuous
    B.
    steam
    C.
    azerotropic
    D.
    none of these

  11. Large scale drying of wheat is done in a __________ dryer.

  12. A.
    fluidised bed
    B.
    spouted bed
    C.
    tray
    D.
    vacuum rotary

  13. Azeotropic distillation is employed to separate

  14. A.
    constant boiling mixture.
    B.
    high boiling mixture.
    C.
    mixture with very high relative volatility.
    D.
    heat sensitive materials.

  15. The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid )

  16. A.
    T
    B.
    T
    C.
    T2
    D.
    T3

  17. Use of natural draft cooling tower is practised, when the air has low

  18. A.
    humidity
    B.
    temperature
    C.
    both 'a' & 'b'
    D.
    neither 'a' nor 'b'

  19. Pressure drop through plate tower as compared to that through packed tower, for the same duty will be

  20. A.
    less
    B.
    more
    C.
    equal
    D.
    either (a) or (b); depends on the packing height