1. According to Poiseuille's law, the permeability for gas flow through a capillary is proportional to (where, μ = gas viscosity)
Correct : B. 1/μ
2. Even though bubble cap towers are very effective for humidification operation, they are not used commonly in industries, because of the
Correct : B. High pressure drop of the gas
3. In case of constant underflow extraction operation, the __________ at all solute concentration.
Correct : C. Both (A) & (B)
4. Which of the following has the same dimension as mass diffusivity?
Correct : D. Both (B) and (C)
5. Packed column distillation is limited to the column __________ metres.
Correct : C. Both (A) & (B)
6. Which of the following decreases during evaporative cooling process with recirculated water supply?
Correct : D. None of these
7. During constant rate period, the rate of drying decreases with the
Correct : C. Both (A) and (B)
8. At what percentage (by volume) of alcohol composition, it forms an azeotrope with water?
Correct : C. 95
9. Which of the following is considered equivalent to one theoretical stage in Mc-Cabe Thiele's method?
Correct : D. Both (B) and (C)
10. Steam distillation is not recommended to be used, if the
Correct : A. Azeotropic mixture is to be separated and the final product is miscible with water
11. It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%).
Correct : C. 71 min
12. In Azeotropic mixture, the equilibrium vapour composition is
Correct : C. Same as liquid composition
13. In rectifying section of a continuous distillation column, the
Correct : B. Vapour is enriched with high boilers
14. The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives
Correct : C. Low pressure drop and low hold up
15. Diameter of raschig rings used in packed tower in industry is normally around __________ inches.
Correct : A. 2
16. The ratio of Murphree plate efficiency to point efficiency is 1 in a __________ flow model.
Correct : B. Perfectly mixed
17. Plate efficiency
Correct : A. Is a function of the mass transfer between liquid and vapour
18. Weeping in a distillation column
Correct : D. Results due to very low gas velocity
19. The expression, y(1 - x)/x(1 - y) is for
Correct : B. Relative volatility
20. The process employing desorption of the absorbed solute by a solvent is called
Correct : A. Elution
21. In McCabe-Thiele method, at infinite reflux ratio
Correct : C. Both the operating lines coincide with the diagram
22. Plate towers are preferred to packed towers, when large temperature changes are involved, because of the reason that the
Correct : A. Packing may be crushed due to thermal expansion/contraction of the components of the equipments
23. Pick out the correct statement.
Correct : C. For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion
24. A binary mixture of benzene and cyclohexane is separated by
Correct : B. Extractive distillation
25. Mass transfer co-efficient 'K' according to penetration theory varies with mass diffusivity as
Correct : A. D 0.5
26. Free flowing granular materials can be best dried in a __________ drier.
Correct : A. Rotary
27. In a packed bed absorption column, the channelling will be noted by the
Correct : B. Sharp drop in pressure drop
28. The ratio of Murphree plate efficiency to point efficiency is always > 1 in a __________ flow model.
Correct : A. Plug
29. Fractional solvent extraction
Correct : B. Employs two solvents
30. At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid
__________ that in dry packed tower.
Correct : A. Is greater than
31. During dehumidification of unsaturated air wet bulb temperature & partial pressure of vapor are not constant. However, during evaporative cooling process with recirculated water supply, the __________ remains constant.
Correct : A. Wet bulb temperature
32. Wet bulb and dry bulb temperatures becomes identical at __________ percent saturation
curve.
Correct : A. 100
33. __________ is the separation technique used for desalination of sea water.
Correct : B. Reverse osmosis
34. The partial pressure distribution of an ideal gas diffusing through another stagnant ideal
gas at steady state follows a/an __________ law.
Correct : A. Exponential
35. Out of two equilibrium curves, first one lies above the diagonal and the second lies below the diagonal in the x-y plot. It means that separation by distillation is
Correct : C. More readily done in the second case compared to first one
36. According to Chilton-Colburn analogy for mass transfer, NSt.NSc 2/3 is equal to
Correct : B. f/2
37. Very tall packed towers are divided into series of beds to
Correct : B. Avoid channelling
38. If „f’ is defined as above, then which of the following applies to a feed at dew point?
Correct : A. f = 1
39. Separation of the isotopes of helium for scientific investigations is done by
Correct : B. Thermal diffusion
40. Flash distillation is suitable for the separation of components
Correct : C. Having very wide boiling points
41. The McCabe ΔL law states that the
Correct : C. Linear crystal growth rate does not depend on the crystal size
42. When both the fluids flow concurrently in an absorber, the slope of the operating line is
Correct : A. -ve
43. Steam distillation is used for separation of high boiling
Correct : C. Both (A) and (B)
44. The relative saturation of a partially saturated mixture of vapour and gas can be increased
by __________ of the mixture.
Correct : D. Both (B) and (C)
45. Pick out the correct statement.
Correct : A. Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non-ideal binary system by distillation
46. Pick out the wrong statement.
Correct : B. Relative volatility of a binary mixture changes appreciably with the minor change in temperature
47. For a fixed number of ideal stages in a distillation column, as the reflux ratio is increased, the difference in composition between the top and bottom product streams
Correct : A. Increases
48. __________ diffusion is used for separating the isotopes of methane.
Correct : A. Thermal
49. Pick out the wrong statement.
Correct : C. According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(B)P - 3, Q - 2
50. For a distillation column operating at minimum reflux, the
Correct : C. Number of plates required will be maximum
51. Compound A is extracted from a solution of A + B into a pure solvent S. A Co-current unit is used for the liquid-liquid extraction. The inlet rate of the solution containing A is 200 moles of B/hr.m2 and the solvent flow, rate is 400 moles of S/m2 . hr. The equilibrium data is represented by Y = 3X2 , where Y is in moles of a A/moles of B and X is in moles A/moles of S. The maximum percentage extraction achieved in the unit is
Correct : B. 50%
52. Mass transfer co-efficient is directly proportional to DAB 0.5, according to __________ theory.
Correct : A. Penetration
53. Which of the following gas-liquid contacting devices incurs the least pressure drop for a
particular duty?
Correct : D. Bubble cap tower
54. For experimental determination of mass transfer co-efficient by wetted wall tower, the
mass transfer area is
Correct : C. Known
55. With decrease in the throughput (compared with the design capacity) for a bubble cap
distillation column, its efficiency
Correct : A. Increases
56. Diameter to height ratio for a raschig ring is
Correct : A. 1
57. Which of the following operations does not involve leaching?
Correct : D. Removing nicotine from its water solution by kerosene
58. Flooding in a distillation column is detected by a sharp
Correct : D. Increase in pressure drop
59. In case of an ideal solution, the total vapor pressure varies __________ with the composition expressed as mole fraction,
Correct : B. Linearly
60. With increase in temperature, the rate of extraction in leaching (solid-liquid extraction system).
Correct : A. Increases
61. Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular diffusion, if
Correct : D. There is equimolar counter diffusion
62. Absorption accompanied by heat evolution results in
Correct : C. Decrease in equilibrium solubility
63. The solvent used in liquid extraction should not have high latent heat of vaporisation, because
Correct : C. Its recovery cost by distillation may be prohibitively high
64. Mass transfer co-efficient varies as DAB
0.5, according to the __________ theory.
Correct : B. Surface renewal
65. The suitable evaporator for concentration of foaming liquids is a __________ evaporator.
Correct : A. Long tube
66. In stripping section of continuous distillation column, the
Correct : B. Liquid is enriched with high boiler
67. An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii)
Correct : A. Less number of trays are required
68. The Schmidt number which is defined as, μ/ρ D, is the ratio of the
Correct : A. Momentum diffusivity to the mass diffusivity
69. NSc/NPr is called the
Correct : B. Lewis number
70. At constant pressure, with increase of temperature, the dew point will
Correct : A. Increase
71. Pick out the correct statement.
Correct : B. Electrodialysis is used in the manufacture of NaOH
72. The percentage humidity is less than the relative humidity only at __________ percent humidity.
Correct : C. Both zero and hundred
73. 'ADDUCTS' and 'CLATHRATES' are used in case of
Correct : B. Crystallisation
74. __________ is concerned with the adsorption equilibria.
Correct : C. Freundlich equation
75. In most of the vacuum crystalliser, vacuum is generally produced by means of a
Correct : C. Steam jet ejector with a barometric condenser
76. In a distillation column, with increase in the reflux ratio, the heat removed in the cooler
Correct : A. Increases
77. The feed to fractionating column is changed from saturated vapour to saturated liquid. If the separation and reflux ratio remains unchanged, the number of ideal stages will
Correct : A. Increase
78. During constant rate drying period, vaporisation rate per unit drying surface area
Correct : C. Does not change with time
79. A coalescer in a mixer-settler liquid-liquid extraction column
Correct : D. All 'a', 'b', & 'c'
80. In which of the following unit operations, the selectivity is an important parameter?
Correct : B. Solvent extraction
81. Flash distillation is suitable for separating the constituents of a binary system, which
Correct : B. Have very wide boiling points
82. In case of an unsaturated mixture of gas and vapor, the percentage saturation is __________ its relative saturation.
Correct : A. Lower than
83. At __________ reflux, theoretical number of plates in a distillation coloumn is calculated
using Fenske-Underwood equation.
Correct : B. Total
84. Pick out the correct statement.
Correct : C. In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux
85. In physical terms, Schmidt number means
Correct : C. Momentum diffusivity/mass diffusivity
86. Unit operation involved in the prilling of urea is
Correct : D. Both (B) and (C)
87. Degree of freedom for leaching and solvent extraction process is
Correct : D. 3
88. With increase in temperature, the solubility of gases in liquids, at fixed pressure
Correct : B. Decreases
89. The equipment used in the extraction of highly corrosive radioactive liquids is
Correct : A. Pulse column
90. Tea percolation employs
Correct : B. Leaching
91. When the solvent dissolves very little of solute, then
Correct : C. Large quantity of solvent is required to extract the solute
92. Bollman extractor
Correct : B. Is used for extraction of oil from oilseed
93. In case of absorption, both the operating and equilibrium lines will be straight for
Correct : C. Dilute solutions and isothermal operation
94. The most economical range of absorption factor is
Correct : C. 1.25 to 2
95. In the constant rate period of the rate of drying curve for batch drying,
Correct : C. Surface evaporation of unbound moisture occurs
96. Back-trapping in a distillation column
Correct : B. Decreases tray efficiency
97. Rose oil is extracted from rose leaves using __________ distillation.
Correct : D. Steam
98. The value of NA/(NA + NB), for steady state equimolal counter diffusion of two gases 'A' and 'B' is
Correct : B. ∞
99. Pick out the wrong statement pertaining to the rotary dryer.
Correct : C. Rotary dryer is suitable for drying sticky material
100. Which of the following is not a unit of mass transfer co-efficient?