1. Selectivity of the solvent used in solvent extraction should be
Correct : B. > 1
2. The relative humidity of air decreases in-spite of an increase in the absolute humidity, when the
Correct : A. Temperature rises
3. The dew point of a saturated gas phase equals the __________ temperature.
Correct : A. Gas
4. The amount of steam required per unit quantity of distillate in case of steam distillation
will be reduced by
Correct : C. Both (A) and (B)
5. Priming in a distillation column
Correct : C. Is characterised by the presence of foam throughout the space between trays
6. Separation of a mixture of two gases by absorption in the liquid solvent depends upon the difference in their
Correct : C. Solubility
7. The efficiency of a plate column will be maximum, when the flow is ideal __________ the plate.
Correct : C. Both (A) & (B)
8. __________ columns are used for liquid dispersion in a continuous gas phase.
Correct : A. Packed
9. Pick out the wrong statement.
Correct : C. The operating line lies above the equilibrium curve in case of a gas desorber
10. An alkaline solution is used to reduce the concentration of carbon dioxide in a stream from 10% to 0.1% by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is:
Correct : B. 4.605
11. The overall mass transfer co-efficient for the absorption of SO2 in air with dilute NaOH solution can be increased substantially by
Correct : A. Increasing the gas film co-efficient
12. Air initially at 101. 3 kPa and 40°C and with a relative humidity of 50%, is cooled at constant pressure to 30°C. The cooled air has a
Correct : C. Higher relative humidity
13. When the psychometric ratio is __________ then the adiabatic saturation temperature and wet bulb temperature becomes equal.
Correct : A. 1
14. With increase in the concentration of the adsorbate, the integral heat of adsorption
Correct : B. Decreases
15. Use of raschig rings in place of crushed stones as packing in packed beds (other things being same)
Correct : C. Decreases pressure drop, increases surface area
16. A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process?
Correct : D. Temperature of the solid
17. Fenske equation for determining the minimum number of theoretical stages in distillation
column holds good, when the
Correct : A. Relative volatility is reasonably constant
18. When the __________ the relative humidity of air decreases, despite an increase in the
absolute humidity.
Correct : A. Temperature rises
19. Pick out the wrong statement.
Correct : D. Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum
20. Detergent solution is dried to a powder in a
Correct : A. Spray dryer
21. Stefan's law describes the mass transfer by
Correct : C. Both 'a' & 'b'
22. Which of the following equipments is not used in liquid-liquid extraction?
Correct : A. Pachuka tank
23. Flights in a rotary dryer are provided to
Correct : A. Lift and shower the solids thus exposing it thoroughly to the drying action of the gas
24. In a forced draft cooling tower, water is cooled from 95 to 80°F by exposure to air with a wet bulb temperature of 70°F. In this case, the
Correct : C. Both (A) & (B)
25. To increase the absorption factor, (where, G = gas flow rate, S = solvent flow rate)
Correct : C. Increase 'S' and decrease 'G'
26. The adiabatic saturation curve for a vapour-gas mixture is
Correct : B. Slightly concave upward
27. For the case of flow of air past a wet bulb thermometer (air water vapour system), the approximate value of h2/ky .Cz
is around
Correct : C. 1
28. The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the __________ temperature.
Correct : D. None of these
29. Absorption factor is defined as (where, S1 = slope of the operating line S2 = slope of the equilibrium curve)
Correct : B. S1/S2
30. At what value of reflux ratio, number of theoretical plates in a distillation column is minimum?
Correct : C. ∞
31. Under conditions of flooding in packed tower, the gas pressure drop
Correct : D. Is maximum
32. With increase in solvent rate, the number of transfer units, NtoG, for a fixed degree of absorption from a fixed amount of gas
Correct : B. Decreases
33. Absorption accompanied with chemical reaction is exemplified by the absorption of
Correct : C. SO2 in alkaline solution
34. For turbulent mass transfer in pipes, the Sherwood number depends on the Reynolds
number as
Correct : C. Re0.83
35. In a counter-current liquid extractor
Correct : C. Only one of the liquids may be pumped at any desired rate
36. The vapour pressure exerted by the moisture contained in a wet solid depends upon the
Correct : D. All (A), (B) and (C)
37. In distillation, overhead product contains
Correct : C. Any number of components
38. Equilibrium-moisture curves of different solids
Correct : A. Are different
39. The caking of crystals can be prevented by
Correct : D. Both (A) and (C)
40. In McCabe-Thiele method of theoretical plate calculation for a distillation column, the operating lines of stripping and rectifying sections coincide with the diagonal at __________ reflux.
Correct : A. Total
41. Mass transfer co-efficient (K) and diffusivity (D) are related according to film theory as
Correct : A. K ∝ D
42. Steady state equimolal counter diffusion occurs in case of
Correct : C. Binary phase distillation
43. On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapor feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in
Correct : C. Increased reflux ratio
44. __________ is used as an 'entrainer' for the separation of acetic acid-water mixture by distillation.
Correct : C. Butyl acetate
45. Mass transfer rate between two fluid phases does not necessarily depend on the __________ of the two phases.
Correct : A. Chemical properties
46. If mass diffusivity in a mixture is equal to the thermal diffusivity, then the Lewis number is
Correct : B. 1
47. Which of the following solutions will follow Raoult's law most closely?
Correct : A. A solution of benzene, toluene and o-xylene
48. For continuous drying of granular or crystalline material, the dryer used is the __________
dryer.
Correct : C. Rotary
49. Pick out the correct statement.
Correct : D. All (A), (B) and (C)
50. __________ column is preferred to be used, when a high liquid hold up is required in a reactor for gas-liquid reaction.
Correct : B. Bubble
51. As complete saturation of an adsorbent is approached, the differential heat of adsrop-tion approaches
Correct : A. That of normal condensation
52. During bottling of cold drinks (e.g. Pepsi), the main resistance to mass transfer for the absorption of carbon dioxide in water lies in the
Correct : B. Liquid film
53. Relative humidity is the ratio of the
Correct : B. Partial pressure of the vapour to the vapour pressure of the liquid at gas temperature
54. In the absorption of ammonia in water, the main resistance to absorption is by the
__________ phase.
Correct : B. Gas
55. In paper industry, paper is dried in a __________ dryer.
Correct : B. Heated cylinder
56. Tray spacing in a distillation column of dia 10-12 ft. used in petroleum refinery may be around __________ inches.
Correct : B. 30
57. Which of the following plays an important role in problems of simultaneous heat and mass transfer?
Correct : A. Lewis number
58. In a moderately sized packed absorption tower, channelling (which is most severe with stacked packings) can be minimised by taking the ratio of tower diameter to packing diameter
Correct : C. > 8:1
59. If f = moles of vapour present per mole of feed, then the slope of feed line is (McCabeThiele method)
Correct : C. -1/f
60. Pick out the wrong statement.
Correct : C. The operating pressure in solvent extraction system should be below vapor pressures of all components
61. Mass transfer co-efficient of liquid is
Correct : A. Affected more by temperature than that for gases
62. Heat sensitive materials with very high latent heat of vaporisation may be economically separated using
Correct : A. Liquid extraction
63. The reciprocal of stripping factor is termed as
Correct : C. Absorption factor
64. A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state,
Correct : D. The top and bottom compositions correspond to the maximum enrichment available
65. In distillation columns, the number of bubble caps per tray primarily depends upon the
Correct : C. Allowable gas and liquid velocities
66. Batch tray dryers suffers from the disadvantage of
Correct : C. High labour cost & low heat economy
67. For absorbing a sparingly soluble gas in a liquid
Correct : C. Liquid side mass transfer co-efficient should be decreased
68. Smoke is an example of
Correct : B. Solid dispersed in gas
69. Low viscosity absorbent is preferred for reasons of
Correct : D. All (A), (B) and (C)
70. Pick out the wrong statement.
Correct : D. Zirconia probe is used for the humidity measurement
71. The wetted wall tower is used to determine
Correct : A. Individual mass transfer co-efficient (M.T.C.) in gaseous system
73. In a solution containing 0.30 Kg mole of solute and 600 kg of solvent, the molality is
Correct : A. 0.50
74. Small dia distillation column can be a
Correct : A. Packed column
75. Prandtl number for water at 20°C is about
Correct : A. 7
76. Relative volatility does not change appreciably with the change in
Correct : A. Temperature
77. The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is
Correct : A. +ve
78. A minimum boiling azeotrope is exemplified by
Correct : B. Acetone-carbon disulphide
79. Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture.
Correct : A. Bound
80. Which is the controlling factor for a drum drier?
Correct : B. Heat transfer
81. 1 kg of a saturated aqueous solution of a highly soluble component A at 60°C is cooled to 25°C. The solubility limits of A are (0.6 kgA/kg water) at 60°C and (0.2 kgA/kg water) at 25°C. The amount in kg of the crystals formed is:
Correct : C. 0.2
82. Which of the following is not a continuous drier?
Correct : D. Tray drier
83. Pick out the wrong statement:
Correct : D. Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition
84. In an operating distillation column, the
Correct : C. Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column
85. Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined
by the measurement of the __________ of a fibre.
Correct : A. Electrical resistance
86. As per Gilliland's equation, the diffusivity is
Correct : D. All 'a', 'b' & 'c'
87. Pick out the wrong statement.
Correct : C. For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 × 10-2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10-2m/s
88. If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that
Correct : D. On heating, a vapor phase will appear; while on cooling, a solid phase will appear
89. Leaching of coffee from coffee beans is done by
Correct : A. Hot water
90. In case of an absorber, the operating
Correct : A. Line always lies above the equilibrium curve
91. Desirable value of absorption factor in an absorber is
Correct : C. > 1
92. Radioactive nuclear waste is treated in
Correct : C. Pulsed column extractor
93. In case of a desorber (stripper), the
Correct : B. Operating line always lies below the equilibrium curve
94. In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalent to a theoretical plate HTUOG = overall gas phase height of a transfer unit).
Correct : C. Both (A) & (B)
95. Make up water is required in a cooling tower to replace the water lost by
Correct : D. All (A), (B) and (C)
96. Langmuir equation is associated with
Correct : B. Adsorption
97. A packed tower compared to a plate tower for a particular mass transfer operation
Correct : A. Incurs smaller pressure drop
98. Which of the following is an undesirable property for an absorbing solvent?