MCQOPTIONS
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MCQOPTIONS
This section includes 122 Mcqs, each offering curated multiple-choice questions to sharpen your Mass Transfer knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
The diffusivity, DAB (for component A diffusing in B) is equal to the diffusivity DBA (forcomponent B diffusing in A) for a binary mixture of |
| A. | Newtonian liquids |
| B. | Non-Newtonian liquids |
| C. | Ideal gases |
| D. | Real gases |
| Answer» D. Real gases | |
| 52. |
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: |
| A. | 9.21 |
| B. | 4.605 |
| C. | 100 |
| D. | 0.001 |
| Answer» C. 100 | |
| 53. |
The amount of steam required per unit quantity of distillate in case of steam distillationwill be reduced by |
| A. | Raising the temperature |
| B. | Lowering the total pressure |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» D. Neither (A) nor (B) | |
| 54. |
Which of the following is a suitable absorbent for removal of H2S from natural gas? |
| A. | Vetrocoke solution |
| B. | Monoethanolamine (MEA) |
| C. | Dilute |
| D. | Hot water |
| Answer» C. Dilute | |
| 55. |
In case of __________ distillation, a solvent is added to alter the relative volatility of themixture to be separated. |
| A. | Molecular |
| B. | Azeotropic |
| C. | Extractive |
| D. | Flash |
| Answer» D. Flash | |
| 56. |
Fenske-Underwood equation used for calculating the minimum number of theoreticalplates in distillation column is valid for |
| A. | Constant molal overflow |
| B. | Total reflux |
| C. | Constant relative volatility |
| D. | All (A), (B) and (C) |
| Answer» E. | |
| 57. |
__________ number indicates the ratio of the rates of the heat and mass transfer incase of acooling tower. |
| A. | Sherwood |
| B. | Stanton |
| C. | Lewis |
| D. | Peclet |
| Answer» D. Peclet | |
| 58. |
At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbent |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | Increases exponentially |
| Answer» C. Remains unchanged | |
| 59. |
The recovery of penicillin from the acidified fermentation broth is done by |
| A. | Distillation |
| B. | Evaporation |
| C. | Absorption |
| D. | Liquid extraction |
| Answer» E. | |
| 60. |
Corresponding to Nusselt number in heat transfer, the dimensionless group in masstransfer is the __________ number. |
| A. | Sherwood |
| B. | Schmidt |
| C. | Peclet |
| D. | Stanton |
| Answer» B. Schmidt | |
| 61. |
Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are: |
| A. | 4 |
| B. | 8 |
| C. | 9 |
| D. | 10 |
| Answer» D. 10 | |
| 62. |
Adsorption is a unit operation which generally involves __________ systems. |
| A. | Liquid-solid |
| B. | Gas-solid |
| C. | Fluid-solid |
| D. | Solid-solid |
| Answer» D. Solid-solid | |
| 63. |
Sand is dried in foundries in a _________drier. |
| A. | Rotary |
| B. | Fluidised bed |
| C. | Vacuum |
| D. | Spray |
| Answer» C. Vacuum | |
| 64. |
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). |
| A. | Straight |
| B. | Parallel |
| C. | Both (A) & (B) |
| D. | Neither (A) nor (B) |
| Answer» D. Neither (A) nor (B) | |
| 65. |
Fenske equation for determining the minimum number of theoretical stages in distillationcolumn holds good, when the |
| A. | Relative volatility is reasonably constant |
| B. | Mixture (to be separated) shows negative deviation from ideality |
| C. | Mixture (to be separated) shows positive deviation from ideality |
| D. | Multi-component distillation is involved |
| Answer» B. Mixture (to be separated) shows negative deviation from ideality | |
| 66. |
At equilibrium the concentration of water in vapour phase (C*) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is |
| A. | 0.0 |
| B. | 0.2 |
| C. | 0.4 |
| D. | 1.0 |
| Answer» D. 1.0 | |
| 67. |
For continuous drying of granular or crystalline material, the dryer used is the __________dryer. |
| A. | Tunnel |
| B. | Tray |
| C. | Rotary |
| D. | None of these |
| Answer» D. None of these | |
| 68. |
At what value of reflux ratio, number of theoretical plates in a distillation column is minimum? |
| A. | 0 |
| B. | 1 |
| C. | ∞ |
| D. | < 1 |
| Answer» D. < 1 | |
| 69. |
At __________ reflux, theoretical number of plates in a distillation coloumn is calculatedusing Fenske-Underwood equation. |
| A. | Operating |
| B. | Total |
| C. | Minimum |
| D. | Maximum permissible |
| Answer» C. Minimum | |
| 70. |
With increase in temperature, the rate of extraction in leaching (solid-liquid extraction system). |
| A. | Increases |
| B. | Decreases |
| C. | Remain unaffected |
| D. | Increases Linearly |
| Answer» B. Decreases | |
| 71. |
A natural draft cooling tower is filled with wooden grids, which covers about __________percent of the tower height. |
| A. | 10-15 |
| B. | 30-40 |
| C. | 70-80 |
| D. | 90-100 |
| Answer» B. 30-40 | |
| 72. |
For the flow of gases through a capillary, with increase in temperature, the permeability__________ as per Knudsen law. |
| A. | Increases |
| B. | Decreases |
| C. | Remain same |
| D. | Either (A) or (B); depends on the gas |
| Answer» B. Decreases | |
| 73. |
With increase in the liquid flow rate at a fixed gas velocity in a randomly packed countercurrent gas-liquid absorption column, the gas pressure drop |
| A. | Decreases |
| B. | Remains unchanged |
| C. | Increases |
| D. | Decreases exponentially |
| Answer» D. Decreases exponentially | |
| 74. |
Dried finished product sampled from various parts of a __________ dryer exhibits nonuniformity in the moisture content. |
| A. | Rotary |
| B. | Tray |
| C. | Freeze |
| D. | None of these |
| Answer» C. Freeze | |
| 75. |
The equation, NA = (DAB . Pt /RTZ) (y1 - y2) is for |
| A. | Steady state equimolar counter diffusion |
| B. | Fick's first law of diffusion |
| C. | Steady state diffusion for stagnant case |
| D. | Liquid M.T.C. by penetration theory |
| Answer» B. Fick's first law of diffusion | |
| 76. |
Pore size of the molecular sieve 5A is __________ mm. |
| A. | 5 |
| B. | 0.5 |
| C. | 0.05 |
| D. | 50 |
| Answer» C. 0.05 | |
| 77. |
The Knudsen diffusivity is proportional to (where, T = absolute temperature) |
| A. | √T |
| B. | T2 |
| C. | T |
| D. | T4 |
| Answer» B. T2 | |
| 78. |
Which of the following parameters remains constant during chemical dehumidification? |
| A. | Dry bulb temperature |
| B. | Partial pressure of vapour |
| C. | Wet bulb temperature |
| D. | None of these |
| Answer» B. Partial pressure of vapour | |
| 79. |
The equation, NA = (DAB . Pt /RTZ . PBM) (PA1 - PA2) is for |
| A. | Fick's second law of diffusion |
| B. | Steady state diffusion for stagnant case |
| C. | Liquid M.T.C. by Higbie penetration theory |
| D. | None of these |
| Answer» C. Liquid M.T.C. by Higbie penetration theory | |
| 80. |
In triangular co-ordinates, the ternary composition point falls __________ of the triangle. |
| A. | In the corners |
| B. | Inside |
| C. | On the sides |
| D. | None of these |
| Answer» C. On the sides | |
| 81. |
The velocity, concentration and temperature boundary, for the boundary layer developmenton a flat plate during connective mass transfer will be same, if |
| A. | NSc = 1 |
| B. | NSc = NPr = NLe |
| C. | NPr = NLe |
| D. | NSc = NLe |
| Answer» C. NPr = NLe | |
| 82. |
Molecular sieves are regenerated by heating to __________ °C. |
| A. | < 150 |
| B. | 200-330 |
| C. | > 500 |
| D. | > 1000 |
| Answer» C. > 500 | |
| 83. |
The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). |
| A. | √T |
| B. | T |
| C. | T1.5 |
| D. | T3 |
| Answer» C. T1.5 | |
| 84. |
A 25 cm × 25 cm × 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m × 1m × 1cm flat sheet of the same material is to be dried from one side only. Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is |
| A. | 1000 |
| B. | 1500 |
| C. | 2000 |
| D. | 2500 |
| Answer» B. 1500 | |
| 85. |
In gas-liquid contact operation, the number of ideal stages, N = (xa - xb)/(xb - x*b). This is true when the stripping factor 'S' is |
| A. | S > 1 |
| B. | S < 1 |
| C. | S = 1 |
| D. | S = ∞ |
| Answer» B. S < 1 | |
| 86. |
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, moles/m2, a: interfacial area per unit volume of tower) |
| A. | G/(FG . a) |
| B. | FG/(G . a) |
| C. | (G . a)/FG |
| D. | L/(FG . G) |
| Answer» B. FG/(G . a) | |
| 87. |
For experimental determination of mass transfer co-efficient by wetted wall tower, themass transfer area is |
| A. | Calculated |
| B. | Unknown |
| C. | Known |
| D. | Not required |
| Answer» D. Not required | |
| 88. |
Mass transfer co-efficient 'K' according to penetration theory varies with mass diffusivity as |
| A. | D 0.5 |
| B. | D |
| C. | 1/D |
| D. | D 1.5 |
| Answer» B. D | |
| 89. |
The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc) for the same system is. |
| A. | 100 |
| B. | 10 |
| C. | 5 |
| D. | 1 |
| Answer» C. 5 | |
| 90. |
Which one of the following devices is not used for both the absorption as well as the liquidliquid extraction processes? |
| A. | Packed towers |
| B. | Plate towers |
| C. | Spray towers |
| D. | Wetted wall columns |
| Answer» E. | |
| 91. |
Swenson-Walker crystalliser is a __________ unit. |
| A. | Continuous |
| B. | Batch |
| C. | Semi-batch |
| D. | Cooling (adiabatic)-cum-evaporation |
| Answer» B. Batch | |
| 92. |
What is the degree of freedom of an absorption process in which only one component is transferred between phases? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 93. |
Measurement of the interfacial area of mass transfer is achieved easily & accurately in case of a __________ column. |
| A. | Spray |
| B. | Packed |
| C. | Bubble cap plate |
| D. | Wetted wall |
| Answer» E. | |
| 94. |
Which of the following is directly concerned with Psychrometry? |
| A. | Lewis relationship |
| B. | Galileo number |
| C. | Weber number |
| D. | Dean number |
| Answer» B. Galileo number | |
| 95. |
In a gas-liquid absorption column, for obtaining the maximum absorption efficiency |
| A. | Liquid stream should be distributed uniformly |
| B. | Gas stream should be distributed uniformly |
| C. | Both gas as well as liquid streams should be distributed uniformly |
| D. | By passing should be completely avoided |
| Answer» D. By passing should be completely avoided | |
| 96. |
For a ternary mixture, in which equilateral triangular co-ordinate is used in leaching and extraction, a __________ of the equilateral triangular co-ordinates. |
| A. | Binary mixture is represented by the apex |
| B. | Binary mixture is represented by any point inside |
| C. | Ternary mixture is represented by the sides |
| D. | Pure component is represented by the apex |
| Answer» E. | |
| 97. |
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? |
| A. | Liquid side |
| B. | Gas side |
| C. | Interfacial |
| D. | Both liquid and gas side |
| Answer» C. Interfacial | |
| 98. |
An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapour/kg of dry air is: |
| A. | 0.048 |
| B. | 0.079 |
| C. | 0.122 |
| D. | 0.152 |
| Answer» E. | |
| 99. |
Relative volatility varies with the concentration of component for an ideal solution. The relative volatility of a binary mixture may be defined as the ratio of vapor pressure of component 'A' to that of component 'B', when |
| A. | Only vapor phase follows Raoult's law |
| B. | Only liquid phase obeys Dalton's law |
| C. | Liquid phase obeys Dalton's law and vapor phase obeys Raoult's law |
| D. | Vapor phase obeys Dalton's law and liquid phase obeys Raoult's law |
| Answer» E. | |
| 100. |
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 |
| A. | 25% |
| B. | 50% |
| C. | 70% |
| D. | 90% |
| Answer» C. 70% | |