MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 854 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
The diffusion co-efficient in m /s. of acetic acid in benzene (liquid in liquid) is |
| A. | 2.09 x 10 |
| B. | 2.09 x 10 |
| C. | 2.09 x 10 |
| D. | 2.09 x 10 |
| Answer» D. 2.09 x 10 | |
| 52. |
Condensation of a vapour-gas mixture just begins, when (where, = partial pressure of the vapour = vapour pressure of the liquid ) |
| A. | = |
| B. | >> |
| C. | < |
| D. | << |
| Answer» B. >> | |
| 53. |
The overall mass transfer co-efficient for the absorption of SO in air with dilute NaOH solution can be increased substantially by |
| A. | increasing the gas film co-efficient. |
| B. | increasing the liquid film co-efficient. |
| C. | increasing the total pressure. |
| D. | decreasing the total pressure. |
| Answer» B. increasing the liquid film co-efficient. | |
| 54. |
Liquid diffusivity is of the order of __________ cm /second. |
| A. | 0.01 |
| B. | 0.1 |
| C. | 10 |
| D. | to 10 |
| E. | > 1 |
| Answer» D. to 10 | |
| 55. |
In case of liquids, the binary diffusivity is proportional to (where, = temperature) |
| A. | 1/ |
| Answer» B. | |
| 56. |
The diffusivity, (for component diffusing in ) is equal to the diffusivity (for component diffusing in ) for a binary mixture of |
| A. | Newtonion liquids |
| B. | non-Newtonion liquids |
| C. | ideal gases |
| D. | real gases |
| Answer» D. real gases | |
| 57. |
The diffusivity () in a binary gas mixture is related to the temperature () as |
| A. | ∝ |
| B. | ∝ |
| C. | ∝ |
| D. | ∝ |
| Answer» D. ∝ | |
| 58. |
If and are the relative volatilities when the pressure in the distillation column is 1 and 2 atm respectively. Pick out the correct statement. |
| A. | = |
| B. | = 2 |
| C. | = 0.5 |
| D. | none of these |
| Answer» E. | |
| 59. |
Mass transfer co-efficient is directly proportional to , according to __________ theory. |
| A. | penetration |
| B. | surface renewal |
| C. | film |
| D. | none of these |
| Answer» B. surface renewal | |
| 60. |
With increase in solvent rate, the number of transfer units, , for a fixed degree of absorption from a fixed amount of gas |
| A. | increases |
| B. | decreases |
| C. | decreases linearly |
| D. | remains unaffected |
| Answer» C. decreases linearly | |
| 61. |
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.m and the solvent flow, rate is 400 moles of S/m. hr. The equilibrium data is represented by Y = 3X , 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% | |
| 62. |
In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y = 0.9X, where Y is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer. |
| A. | The entire amount of C is transferred to solvent B. |
| B. | Less than 2 kg but more than 1 kg of C is transferred to solvent B. |
| C. | Less than 1 kg of C is transferred to B. |
| D. | No amount of C is tranferred to B. |
| Answer» B. Less than 2 kg but more than 1 kg of C is transferred to solvent B. | |
| 63. |
The surface renewal frequency in Danckwerts' model of mass transfer is given by (: mass transfer co-efficient) |
| A. | . |
| B. | / |
| C. | / |
| Answer» B. / | |
| 64. |
Gaseous diffusivity at atmospheric pressure is of the order of __________ cm/second. |
| A. | 1 |
| B. | 1 to 5 |
| C. | 5 to 10 |
| D. | > 10 |
| Answer» B. 1 to 5 | |
| 65. |
In a packed tower, the value of HETP equals HTU, when the equilibrium and the operating lines are (where, HETP = height equivalant to a theoretical plate HTU = 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) | |
| 66. |
A distillation column separates 10000 kg/hr of a benzene-toluene mixture as shown in the figure below : In the figure x, x and x represent the weight fraction of benzene in the feed, distillate and residue respectively. The reflux ratio is |
| A. | 0.5 |
| B. | 0.6 |
| C. | 1.0 |
| D. | 2.0 |
| Answer» C. 1.0 | |
| 67. |
Unsaturated air (with dry bulb and wet bulb temperatures being 45°C and 25°C respectively) is passed through a water spray chamber maintained at 23°C. The air will be cooled and |
| A. | humidified with wet bulb temperature decreasing. |
| B. | humidified at constant wet bulb temperature. |
| C. | dehumidified. |
| D. | none of these |
| Answer» B. humidified at constant wet bulb temperature. | |
| 68. |
The Schmidt number which is defined as, μ/ρ , is the ratio of the |
| A. | momentum diffusivity to the mass dif-fusivity. |
| B. | thermal diffusivity to the mass diffusivity. |
| C. | momentum diffusivity to the thermal diffusivity. |
| D. | none of these. |
| Answer» B. thermal diffusivity to the mass diffusivity. | |
| 69. |
If is defined as above, then which of the following applies to a feed at dew point ? |
| A. | = 1 |
| B. | < 1 |
| C. | > 1 |
| D. | 0 < |
| E. | < 1 |
| Answer» B. < 1 | |
| 70. |
In a single stage extraction process, 10 kg of pure solvent (containing no solute A) is mixed with 30 kg of feed containing at a mass fraction x = 0.2. The mixture splits into an extract phase and a raf-finate phase containing at x = 0.5 and x = 0.05 respectively. The total mass of the extract phase is (in Kg) |
| A. | 6.89 |
| B. | 8.89 |
| C. | 10 |
| D. | 8.25 |
| Answer» C. 10 | |
| 71. |
Penetration theory relates the average mass transfer co-efficient () with diffusivity () as |
| A. | ∝ |
| B. | ∝ |
| C. | ∝ |
| D. | ∝ |
| Answer» C. ∝ | |
| 72. |
Unsaturated air (with dry and wet bulb temperatures being 35 and 25°C respectively) is passed through water spray chamber maintained at 35°C. The air will be |
| A. | cooled |
| B. | humidified |
| C. | both (a) & (b) |
| D. | dehumidified |
| Answer» C. both (a) & (b) | |
| 73. |
According to Chilton-Colburn analogy for mass transfer, . is equal to |
| A. | /2 |
| B. | 2 |
| C. | 1/ |
| Answer» C. 1/ | |
| 74. |
HS present in naphtha reformed gas is removed by absorbing with |
| A. | ethanolamine |
| B. | K |
| C. | CO |
| D. | HCl |
| E. | vacuum gas oil |
| Answer» B. K | |
| 75. |
Mass transfer co-efficient '' according to penetration theory varies with mass dif-fusivity as |
| A. | 1/ |
| Answer» B. | |
| 76. |
According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the coloumn. |
| A. | 5 |
| B. | 9 |
| C. | 12 |
| D. | 28 |
| Answer» D. 28 | |
| 77. |
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) |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» B. [B]. | |
| 78. |
The rough value of diffusion co-efficient of water vapor into air at 25°C may be about __________ cm2/sec. |
| A. | 0.25 |
| B. | 2.5 |
| C. | 1.25 |
| D. | 0.0025 |
| Answer» B. 2.5 | |
| 79. |
Which of the following is not a unit of mass transfer co-efficient ? |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | None of these |
| Answer» E. | |
| 80. |
A mixture of 10% C6H6 vapour in air at 25°C and 750 mm Hg has a dew point of 20°C. Its dew point at 30°C and 700 mm Hg will be around __________ °C. |
| A. | 21.7 |
| B. | 20 |
| C. | 27.3 |
| D. | 18.7 |
| Answer» E. | |
| 81. |
Pick out the correct relationship. (where, Ri = internal reflux ratio Ro = external reflux ratio. ) |
| A. | 1 + Ro) = Ro/Ri |
| B. | 1 - Ro) = Ro/Ri |
| C. | 1 + Ri) = Ro/Ri |
| D. | 1 - Ri) = Ro/Ri |
| Answer» B. 1 - Ro) = Ro/Ri | |
| 82. |
Which of the following decreases during evaporative cooling process with recirculated water supply? |
| A. | et bulb temperature |
| B. | elative humidity |
| C. | artial pressure of vapour |
| D. | one of these |
| Answer» E. | |
| 83. |
Which of the following increases during evaporative cooling process with recirculated water supply? |
| A. | et bulb temperature |
| B. | elative humidity |
| C. | artial pressure of vapour |
| D. | oth B and C |
| Answer» E. | |
| 84. |
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 |
| A. | ange is 15°F |
| B. | pproach is 10°F |
| C. | oth A & B |
| D. | either A nor B |
| Answer» D. either A nor B | |
| 85. |
Which of the following can be calculated theoretically using steam table and Dalton's law of partial pressure; if the relative humidity and dry bulb temperature of moist air is known? |
| A. | ew point |
| B. | umidity ratio |
| C. | et bulb temperature |
| D. | one of these |
| Answer» D. one of these | |
| 86. |
A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process? |
| A. | low rate of inlet air |
| B. | elative humidity of outlet air |
| C. | umidity of inlet air |
| D. | emperature of the solid |
| Answer» E. | |
| 87. |
Diffusion co-efficient generally depends upon the temperature, pressure & the nature of the components of the system. Its dimension is not the same as that of the |
| A. | ass transfer co-efficient |
| B. | hermal diffusivity |
| C. | inematic viscosity |
| D. | olumetric diffusivity |
| Answer» B. hermal diffusivity | |
| 88. |
Which of the following psychrometric processes is followed by water vapour laden unsaturated air, when it is passed through solid or liquid adsorbent? |
| A. | ooling and dehumidification |
| B. | eating and dehumidification at almost constant wet bulb temperature |
| C. | ehumidification with dry bulb temperature remaining constant |
| D. | one of these |
| Answer» C. ehumidification with dry bulb temperature remaining constant | |
| 89. |
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. | > 1 |
| B. | < 1 |
| C. | = 1 |
| D. | = ∞ |
| Answer» B. < 1 | |
| 90. |
Which of the following is considered equivalent to one theoretical stage in Mc-Cabe Thiele's method? |
| A. | artial condenser |
| B. | otal condenser |
| C. | eboiler |
| D. | oth B and C |
| Answer» E. | |
| 91. |
Which of the following liquid-vapor contacting devices provides maximum contact surface area for a particular duty? |
| A. | ieve plate column |
| B. | ubble cap column |
| C. | andomly packed column |
| D. | etted wall column |
| Answer» E. | |
| 92. |
Which of the following parameters remains almost constant during adiabatic saturation of unsaturated air? |
| A. | ry bulb temperature |
| B. | ew point |
| C. | et bulb temperature |
| D. | one of these |
| Answer» D. one of these | |
| 93. |
The diffusivity, DAB (for component A diffusing in B) is equal to the diffusivity Dsub>BA (for component B diffusing in A) for a binary mixture of |
| A. | ewtonion liquids |
| B. | on-Newtonion liquids |
| C. | deal gases |
| D. | eal gases |
| Answer» D. eal gases | |
| 94. |
One mole feed of a binary mixture of a given composition is flash vaporised at a fixed P and T. If Raoult's law is obeyed, then changing the feed composition would effect |
| A. | he product composition but not the fraction vaporised |
| B. | he product composition as well as the fraction vaporised |
| C. | he fraction vaporised but not the product composition |
| D. | either the product composition nor the fraction vaporised |
| Answer» D. either the product composition nor the fraction vaporised | |
| 95. |
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) |
| A. | (Xo - XF) |
| B. | (Xo/XF) |
| C. | ln(Xo/XF) |
| D. | Xo ln(Xo/XF) |
| Answer» E. | |
| 96. |
According to Chilton-Colburn analogy for mass transfer, (NSt.NSc)^2/3 is equal to |
| A. | f |
| B. | f/2 |
| C. | 2f |
| D. | 1/f |
| Answer» C. 2f | |
| 97. |
Laboratory determination of the diffusivity of vapor is done by __________ method. |
| A. | wetted wall column |
| B. | Gilliland's |
| C. | Winkel mann's |
| D. | Wike's |
| Answer» D. Wike's | |
| 98. |
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 | |
| 99. |
In a distillation operation, what is the effect of the temperature of the reflux stream (given below) on the condenser and reboiler loads ?Reflux conditions:(i) Reflux stream is completely liquid and is at its bubble point. (ii) Reflux stream is below its bubble point. |
| A. | Condenser and reboiler loads are the same in both the cases. |
| B. | Reboiler load is the same in both the cases but condenser load is higher in case (ii). |
| C. | Condenser load is the same in both the cases but reboiler load is higher in case (ii). |
| D. | Both condensor and reboiler loads are higher in case (ii) as compared to case (i). |
| Answer» E. | |
| 100. |
Weight of 1 m³ of humid air as compared to 1 m³ of dry air, under the same conditions, is |
| A. | less |
| B. | more |
| C. | same |
| D. | unpredictable |
| Answer» B. more | |