41. The diffusivity (D) in a binary gas mixture is related to the temperature (T) as
D ∝ T
D ∝ T0.5
D ∝ T1.5
D ∝ T2
✅ The correct answer is option C.
Mass Transfer MCQs
42. For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, FG:mass transfer co-efficient, mols/m² , a: in-terfacial area per unit volume of tower)
F/(FG.a)
FG/(G.a)
(G.a)/FG
L/(FG.G)
✅ The correct answer is option A.
43. Azeotropic distillation is employed to separate
Constant boiling mixture
High boiling mixture
Mixture with very high relative volatility
Heat sensitive materials
✅ The correct answer is option A.
44. Chemisorption compared to physical absorption has
Lower adsorption rate
Lower capacity of the solvent for the solute gas
Increased utilisation of stagnant zones of the liquid phase
None of these
✅ The correct answer is option C.
45. For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is
Calculated
Unknown
Known
Not required
✅ The correct answer is option C.
46. Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of
Mass diffusivity to momentum diffusivity
Thermal diffusivity to mass diffusivity
Momentum diffusivity to thermal diffusivity
None of these
✅ The correct answer is option B.
47. __________ extractor uses centrifugal force for separating the two phases.
Treybal
Schiebel
Podbielniak
None of these
✅ The correct answer is option C.
48. Tray spacing in a distillation column of dia 10-12 ft. used in petroleum refinery may be around __________ inches.
5
30
60
100
✅ The correct answer is option B.
49. At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid __________ that in dry packed tower.
Is greater than
Is lower than
Is same as
Cannot be predicted as data are insufficient
✅ The correct answer is option A.
50. Occurrence of ‘case hardening’ during drying of a high moisture solid cake __________ the drying rate.
Increases
Decreases
Does not affect
Exponentially increases
✅ The correct answer is option B.