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Chemical Engineering :: Mass Transfer

  1. Which of the following same diameter columns gives lowest pressure drop per unit height ?

  2. A.
    Bubble-cap column
    B.
    Sieve-plate column
    C.
    Packed column (stacked)
    D.
    Randomly packed column

  3. Diffusion in concentrated solutins differs from that in dilute solutions, because of the change in the __________ with the concentration of the solution.

  4. A.
    degree of ideality
    B.
    viscosity
    C.
    both 'a '& 'b'
    D.
    neither 'a' nor 'b'

  5. Stage efficiency in a leaching process depends on the

  6. A.
    time of contact between the solid and the solution
    B.
    rate of diffusion of the solute through the solid and into the liquid
    C.
    both (a) and (b)
    D.
    vapour pressure of the solution

  7. Operating velocity in a packed tower is usually __________ the flooding velocity.

  8. A.
    half
    B.
    twice
    C.
    equal to
    D.
    more than

  9. The Knudsen diffusivity is dependent on the

  10. A.
    molecular velocity only.
    B.
    pore radius of the catalyst only.
    C.
    molecular mean free path only.
    D.
    molecular velocity and por radius of the catalyst.

  11. Minimum possible diameter of a packed coloumn is decided mainly by the

  12. A.
    flooding
    B.
    gas viscosity
    C.
    liquid density
    D.
    liquid hold up

  13. Solvent used in extractive distillation

  14. A.
    is of low volatility.
    B.
    forms a low boiling azeotrope.
    C.
    forms a high boiling azeotrope.
    D.
    does not alter the relative volatility of the original components.

  15. Capacity of a rotary dryer depends on its

  16. A.
    r.p.m
    B.
    inclination with ground surface
    C.
    both (a) and (b)
    D.
    neither (a) nor (b)

  17. The cooling effect in a cooling tower can be speeded up by

  18. A.
    increasing the air velocity and area of exposed wet surface.
    B.
    reducing the barometric pressure.
    C.
    reducing the humidity of the air.
    D.
    all (a), (b) and (c).

  19. The following plot gives the saturated humidity (He) versus temperature (T).Line joining (H1, T1) and (H2, T2) is the constant enthalpy line. Choose the correct one from among the alternatives A, B, C and D.

  20. A.
    T1-Dew point temp; T2-Dry bulb temp; T3-Wet bulb temp.
    B.
    T1-Dew point temp; T2-Wet bulb temp; T3-Dry bulb temp.
    C.
    T1-Wet bulb temp; T2-Dry bulb temp; T3-Dew point temp.
    D.
    T1-Dry bulb temp; T2-Wet bulb temp; T3-Dew point temp.