1. The wet and 'dry bulb temperature for a vapour-gas mixture are 25°C and 30°C respectively. If the mixture is heated to 45°C at constant pressure, the wet bulb temperature will be __________ °C.
Correct : B. > 25
2. Water entrained by circulating air in cooling towers is termed as
Correct : A. Drift
3. Pick out the wrong statement. Raoult's law does not apply, when the
Correct : C. Component molecules are non-polar
4. Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations.
Correct : C. Reynolds number in mass transfer is analogous to Grashoff number in heat transfer
5. Plate efficiency in a distillation column is reduced due to the __________ of liquid.
Correct : D. All (A), (B) & (C)
6. Pick out the wrong statement.
Correct : A. Mass transfer co-efficient does not account for gas-liquid diffusion
7. Blowdown in a cooling tower
Correct : A. Means discarding a small fraction of circulating water to prevent and limit the concentration of salt and impurities
8. Pick out the wrong statement.
Correct : D. The capacity of a distillation column is maximum at total reflux
9. Rayleigh's equation applies to __________ distillation.
Correct : C. Differential
10. In extraction, as the temperature increases, the area of heterogeneity (area covered by binodal curve)
Correct : A. Decreases
11. In most of the mechanically agitated liquid-liquid extractors, baffles or horizontal compartmental plates are provided, which helps in
Correct : D. All 'a', 'b' & 'c'
12. The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m2 /m3 )
Correct : A. 500
13. The slope of 9-line is determined by the
Correct : C. Thermal condition of the feed
14. For a binary mixture with low relative volatility,
Correct : D. An azeotrope may be formed during distillation
15. Freundlich equation applies to the adsorption of solute from
Correct : A. Dilute solutions, over a small concentration range
16. Pick out the wrong statement pertaining to the cooling towers.
Correct : D. Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb temperature
17. The Hatta number is important in
Correct : D. Gas absorption with chemical reaction
18. The dew point of an unsaturated gas-vapor mixture does not depend upon the __________ of the mixture.
Correct : B. Temperature
19. 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 = total surface area for drying Rc = Constant maximum drying rate per unit area X = moisture content (in mass of water/mass of dry solids))
Correct : D. MXo ln(Xo/XF)
20. In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is
Correct : B. Equal to the heat of wetting
21. The critical moisture content in case of drying indicates the __________ rate period.
Correct : A. Beginning of falling
22. Pick out the wrong statement.
Correct : B. Molecular diffusion in solid is much faster than that in liquids
23. Humidity chart is useful for the solution of problems concerning condensation, vaporisation and air conditioning. At a given dry bulb temperature, value of humidity obtained from the humidity chart directly, is in terms of __________ humidity.
Correct : A. Molal
24. Separation of two volatile liquids by distillation makes use of their
Correct : B. Relative volatility
25. Powdery materials can be guarded against caking tendency on storage by
Correct : D. None of these
26. The minimum liquid rate to be used in an absorber corresponds to an operating line
Correct : C. Tangential to the equilibrium curve
27. Leaching of uranium ore and gold ore is done in
Correct : B. Pachuca tanks
28. The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is
Correct : C. -ve
29. For a ternary mixture, in which equilateral triangular co-ordinate is used in leaching and extraction, a __________ of the equilateral triangular co-ordinates.
Correct : D. Pure component is represented by the apex
30. In a gas-liquid absorption column, for obtaining the maximum absorption efficiency
Correct : C. Both gas as well as liquid streams should be distributed uniformly
31. To get high tray efficiency
Correct : A. Interfacial surface between liquid and gas phase should be large
32. Lewis number (Le) is
Correct : A. Sc × Pr
33. Which is not concerned directly with mass transfer?
Correct : D. Froude number
34. Most important factor to be considered in the selection of packings for absorbers is the __________ of packing.
Correct : C. Porosity
35. For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause __________ plate requirement.
Correct : B. Marginal decrease in the number of
36. Experimental determination of __________ is done by wetted wall column method.
Correct : B. Mass transfer co-efficient
37. Ammonia present in the coke oven gas is removed by washing with
Correct : B. Dilute ammoniacal liquor
38. Which of the following provides maximum contact surface for a liquid-vapour system?
Correct : A. Packed tower
39. At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes
Correct : C. ∞
40. Measurement of the interfacial area of mass transfer is achieved easily & accurately in case of a __________ column.
Correct : D. Wetted wall
41. Which of the following is directly concerned with Psychrometry?
Correct : A. Lewis relationship
42. In the layout plan for a vacuum distillation unit, operating at 60 mm Hg, supported by a barometric condenser, the appropriate place for the location of vacuum drum for collecting the distillate will be
Correct : A. At ground level
43. Which of the following is an undesirable property in a tower packing?
Correct : D. Large weight of liquid retained
44. High pressure at the bottom of a distillation tower handling heat sensitive materials results in
Correct : A. Thermal decomposition of bottoms
45. Steady state equimolal counter diffusion is encountered in
Correct : A. Separation of a binary mixture by distillation
46. Minimum reflux ratio in a distillation column results in
Correct : C. Maximum condenser size
47. In a binary distillation column, if the feed contains 40 mole % vapour, the q line will have a slope of
Correct : C. -1.5
48. The individual mass transfer co-efficients (moles/m2 s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling?
Correct : B. Gas side
49. Steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapour-gas mixture is called the __________ temperature.
Correct : B. Wet-bulb
50. In case of unsaturated air
Correct : C. Both (A) and (B)
51. The apex of an equilateral-triangular coordinate (in ternary liquid system) represents a/an
Correct : A. Pure component
52. __________ extractor is used for the concentration of radioactive nuclear waste.
Correct : A. Pulsed column
53. Removal of __________ exemplifies an adsorption unit operation.
Correct : B. Water from petrol
54. Use of packed towers for distillation is generally limited to the
Correct : A. Small sizes
55. Dimension of mass diffusivity is the same as that of
Correct : A. Kinematic viscosity
56. Paper industry employs __________ driers.
Correct : A. Cylinder
57. Pick out the wrong statement
Correct : D. Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure
58. Laboratory determination of the diffusivity of vapor is done by __________ method.
Correct : C. Winkelmann's
59. The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp= M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force.)
Correct : C. Kc = Kp . RT = Km . RT/p
60. Pick out the wrong statement:
Correct : D. The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity
61. The temperature of water cooled in cooling tower is always __________ temperature of entering air.
Correct : A. More than the wet bulb
62. Reverse osmosis is also called
Correct : D. Ultra-filtration
63. Design calculation for multiple component distillation is done by
Correct : D. Tray to tray calculations
64. Absorption (liquid-gas system) with evolution of heat as compared to isothermal absorption results in
Correct : D. All (A), (B) and (C)
65. The unit of volumetric diffusivity is
Correct : A. cm2/sec
66. Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant
Correct : D. All (A), (B) & (C)
67. The diffusivity (D) in a binary gas mixture is related to the pressure (P) as
Correct : C. D ∝ 1/P
68. In liquid extraction, if the selectivity is unity, then
Correct : B. No separation will occur
69. Can the efficiency of a plate in the distillation tower be greater than 100%?
Correct : C. Never
70. H2S present in naphtha reformed gas is removed by absorbing with
Correct : A. Ethanolamine
71. Dorr thickener is an equipment used for
Correct : B. Sedimentation
72. With the lowering of equilibrium pressure, at a given temperature, the amount of adsorbate on the adsorbent
Correct : B. Decreases
73. Mass transfer co-efficient is directly proportional to DAB according to the __________ theory.
Correct : A. Film
74. 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:
Correct : C. 1.24
75. __________ extractor uses centrifugal force for separating the two phases.
Correct : C. Podbielniak
76. With increase in temperature, the mutual solubility of two liquids
Correct : A. Increases
77. The operating cost of a distillation column at minimum reflux ratio is
Correct : A. Minimum
78. For a single component absorber, the operating line is straight only when plotted in term of __________ units.
Correct : B. Mole ratio
79. The cooling effect in a cooling tower cannot be increased by
Correct : D. None of these
80. Separation of __________ employs gaseous diffusion process.
Correct : B. Isotopes of uranium
81. Sodium bicarbonate is produced during soda ash manufacture using a __________ tower.
Correct : B. Baffle
82. Leaching rate is independent of the
Correct : D. None of these
83. With increase in temperature, the rate of leaching increases, because the
Correct : A. Diffusivity of solute increases
84. Bound moisture is that liquid which exerts an equilibrium vapor pressure __________ that of the pure liquid at the given temperature.
Correct : A. Less than
85. The reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. The reflux ratio is
Correct : A. 2
86. Which of the following is not a batch drier?
Correct : C. Fluidised bed drier
87. Acetic acid will be most economically separated from a dilute solution of acetic acid in water by
Correct : A. Solvent extraction
88. The main reason for dividing a tall packed tower into series of small towers is to
Correct : D. Avoid channelling
89. The most efficient cooling tower out of the following is
Correct : A. Induced draft
90. Molecular distillation is
Correct : D. Both (B) and (C)
91. The value of NA/(NA + NB) for steady state molecular diffusion of gas 'A' through nondiffusing gas 'B' is
Correct : A. 1
92. All moisture in a non-hygroscopic material is the __________ moisture.
Correct : C. Unbound
93. Molecular diffusivity of a liquid
Correct : A. Increases with temperature
94. Raschig ring made of porcelain cannot be used for treating concentrated
Correct : C. Alkalis
95. Use of natural draft cooling tower is practised, when the air has low
Correct : C. Both 'a' & 'b'
96. At a fixed pressure, the humidity depends upon the partial pressure of vapor in the mixture. Humidity of a vapour free gas is __________ percent.
Correct : B. zero
97. Tower diameter may be decreased by
Correct : B. Use of increased tray spacing
98. Pick out the wrong statement.
Correct : B. 1 Nm3 of dry air is lighter than 1Nm3 of humid air
99. The humid volume may be increased by increasing the
Correct : C. Both (A) and (B)
100. Pick out the correct relationship. (Where, Ri = internal reflux ratio Ro = external reflux ratio.)