Mass Transfer

31.A packed tower compared to a plate tower for a particular mass transfer operation

  1. Incurs smaller pressure drop
  2. Allows installation of cooling coils
  3. Is less costly when built in large sizes/diameters
  4. Is more suitable, if suspended solids are present in fluid streams

Correct answer: (A)
Incurs smaller pressure drop

32.A plait point is the point on the solubility curve, where the tie line reduces to a point. What is the number of plait point for a ternary system containing two pairs of partially miscible liquids?

  1. 0
  2. 1
  3. 2
  4. 3

Correct answer: (A)
0

33.A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t = 0 for the cubic to spherical tablet is:

  1. 0.54
  2. 1.04
  3. 1.24
  4. 1.94

Correct answer: (C)
1.24

34.A slurry is to be dried to produce flaky solid. Which dryer would you recommend?

  1. Spray dryer
  2. Drum dryer
  3. Rotary dryer
  4. Dielectric dryer

Correct answer: (A)
Spray dryer

35.A solid is being dried in the linear drying rate regime from moisture content Xo to XF. The drying rate is zero at X = 0 and the critical moisture content is the same as the initial moisture Xo. The drying time for M = (Ls/ARc) is (where, L = total mass of dry solid, A = totalsurface area for drying Rc = Constant maximum drying rate per unit area X = moisture content (in mass of water/mass of dry solids))

  1. M(Xo - XF)
  2. M(Xo/XF)
  3. M ln(Xo/XF)
  4. MXo ln(Xo/XF)

Correct answer: (D)
MXo ln(Xo/XF)

36.A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process?

  1. Flow rate of inlet air
  2. Relative humidity of outlet air
  3. Humidity of inlet air
  4. Temperature of the solid

Correct answer: (D)
Temperature of the solid

37.Absorption (liquid-gas system) with evolution of heat as compared to isothermal absorption results in

  1. Decreased solute solubility
  2. Large minimum liquid to gas (L/G) ratio
  3. Large number of trays
  4. All (A), (B) and (C)

Correct answer: (D)
All (A), (B) and (C)

38.Absorption accompanied by heat evolution results in

  1. Increased capacity of the absorber
  2. Increase in equilibrium solubility
  3. Decrease in equilibrium solubility
  4. None of these

Correct answer: (C)
Decrease in equilibrium solubility

39.Absorption accompanied with chemical reaction is exemplified by the absorption of

  1. Ammonia in water
  2. Benzol present in coke oven gas by wash oil
  3. SO2 in alkaline solution
  4. All (A), (B) and (C)

Correct answer: (C)
SO2 in alkaline solution

40.Absorption factor is defined as (where, S1 = slope of the operating line S2 = slope of the equilibrium curve)

  1. S2/S1
  2. S1/S2
  3. S1 - S2
  4. S1 × S2

Correct answer: (B)
S1/S2

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