MCQOPTIONS
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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.
| 151. |
For which of the following unit operations, Lewis number is of significance? |
| A. | Adsorption |
| B. | Binary distillation |
| C. | Gas absorption |
| D. | Humidification |
| Answer» E. | |
| 152. |
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. | Newtonion liquids |
| B. | Non-Newtonion liquids |
| C. | Ideal gases |
| D. | Real gases |
| Answer» D. Real gases | |
| 153. |
Nitrobenzene (boiling point = 210.6°C) is steam distilled at 1 atm pressure.Nitrobenzene will distill off __________ °C. |
| A. | At < 100 |
| B. | At > 210.6 |
| C. | Between 100 and 210 |
| D. | None of these |
| Answer» B. At > 210.6 | |
| 154. |
When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30°C, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system, |
| A. | As the acetone concentration increases, the solubility curves approach each other |
| B. | Both the phases become identical at a particular common point on both the solubility curves called the plait point |
| C. | The distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption termina |
| D. | All of the above |
| Answer» E. | |
| 155. |
If a₁ and a₂ are the relative volatilities when the pressure in the distillation column is 1 and 2 atm respectively. Pick out the correct statement. |
| A. | a₁ = a₂ |
| B. | a₁ = 2a₂ |
| C. | a₁ = 0.5 a₂ |
| D. | None of these |
| Answer» E. | |
| 156. |
Which of the following has the same dimension as mass diffusivity? |
| A. | Momentum flux |
| B. | Kinematic viscosity |
| C. | Thermal diffusivity |
| D. | Both A & B |
| Answer» E. | |
| 157. |
Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular difusion, if |
| A. | Mass transfer is accompanied by reaction |
| B. | Diffusion of A is in stagnant medium B |
| C. | Molecular mean free path is high |
| D. | There is equimolar counter diffusion |
| Answer» E. | |
| 158. |
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 | |
| 159. |
In a single stage extraction process, 10 kg of pure solvent S (containing no solute A) is mixed with 30 kg of feed F containing A at a mass fraction xf = 0.2. The mixture splits into an extract phase E and a raf-finate phase R containing A at xB = 0.5 and xR = 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 | |
| 160. |
Rayleigh's equation applies to __________ distillation. |
| A. | Continuous |
| B. | Steam |
| C. | Differential |
| D. | Flash |
| Answer» D. Flash | |
| 161. |
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. |
| A. | 25 |
| B. | > 25 |
| C. | < 25 |
| D. | - 25 |
| Answer» C. < 25 | |
| 162. |
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 | |
| 163. |
Which of the following adsorbant is used in the refinning of sugar? |
| A. | Bone charcoal |
| B. | Wood charcoal |
| C. | Silica gel |
| D. | Activated clay |
| Answer» B. Wood charcoal | |
| 164. |
Which is not concerned directly with mass transfer? |
| A. | Schmidt number |
| B. | Sherwood number |
| C. | Lewis relationship |
| D. | Froude number |
| Answer» E. | |
| 165. |
Which of the following is directly concerned with psychrometry? |
| A. | Lewis reltionship |
| B. | Galileo number |
| C. | Weber number |
| D. | Dean number |
| Answer» B. Galileo number | |
| 166. |
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. | |
| 167. |
At 750°K and 1 atm, the approximate value of Schmidt number for air is |
| A. | 0.01 |
| B. | 0.1 |
| C. | 1 |
| D. | 10 |
| Answer» C. 1 | |
| 168. |
Mass transfer co-efficient is directly proportional to DAB according to the __________ theory. |
| A. | Film |
| B. | Penetration |
| C. | Surface-renewal |
| D. | None of these |
| Answer» B. Penetration | |
| 169. |
Liquid diffusivity is of the order of __________ cm² /second. |
| A. | 0.01 |
| B. | 0.1 |
| C. | 10-5 to 10-6 |
| D. | > 1 |
| Answer» D. > 1 | |
| 170. |
Which of the following adsorbent is used to decolourise yellow glycerine? |
| A. | Silica gel |
| B. | Alumina |
| C. | Fuller |
| D. | Activated carbon |
| Answer» E. | |
| 171. |
Molecular seives are regenerated by heating to __________ °C. |
| A. | < 150 |
| B. | 200-330 |
| C. | > 500 |
| D. | > 1000 |
| Answer» C. > 500 | |
| 172. |
CO₂ can be absorbed by |
| A. | Hot cupric oxide |
| B. | Heated charcoal |
| C. | Cold Ca(OH)₂ |
| D. | Alumina |
| Answer» C. Cold Ca(OH)₂ | |
| 173. |
A slurry is to be dried to produce flaky solid. Which dryer would you recommend? |
| A. | Spray dryer |
| B. | Drum dryer |
| C. | Rotary dryer |
| D. | Dielectric dryer |
| Answer» B. Drum dryer | |
| 174. |
Prandtl number for water at 20°C is about |
| A. | 7 |
| B. | 70 |
| C. | 0.7 |
| D. | 150 |
| Answer» B. 70 | |
| 175. |
NSc/NPr is called the |
| A. | Psychrometric ratio |
| B. | Lewis number |
| C. | Sherwood number |
| D. | Stantan number |
| Answer» C. Sherwood number | |
| 176. |
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. | F/(FG.a) |
| B. | FG/(G.a) |
| C. | (G.a)/FG |
| D. | L/(FG.G) |
| Answer» B. FG/(G.a) | |
| 177. |
The Schmidt number which is defined as, μ/ρ D, 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 | |
| 178. |
Condensation of a vapour-gas mixture just begins, when (where, p = partial pressure of the vapour P = vapour pressure of the liquid ) |
| A. | P = P |
| B. | P >>P |
| C. | P < P |
| D. | P << P |
| Answer» B. P >>P | |
| 179. |
The diffusion co-efficient in m² /s. of acetic acid in benzene (liquid in liquid) is |
| A. | 2.09 x 10-4 |
| B. | 2.09 x 10-5 |
| C. | 2.09 x 10-9 |
| D. | 2.09 x 10-12 |
| Answer» B. 2.09 x 10-5 | |
| 180. |
The overall mass transfer co-efficient for the absorption of SO₂ 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 | |
| 181. |
Which of the following assumes constant molal vaporisation and overflow? |
| A. | McCabe-Thiele method |
| B. | Ponchan-Savarit method |
| C. | Enthalpy concentration method |
| D. | Plate absorption column |
| Answer» B. Ponchan-Savarit method | |
| 182. |
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 | |
| 183. |
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% | |
| 184. |
Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 x 10⁻³ kg mole/m².s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m² .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is |
| A. | 5.6 x 10⁻⁴ |
| B. | 8.5 x 10⁻⁴ |
| C. | 5.6 x 10⁻³ |
| D. | 8.5 x 10⁻³ |
| Answer» C. 5.6 x 10⁻³ | |
| 185. |
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 | |
| 186. |
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 |
| A. | 0.60 |
| B. | 0.24 |
| C. | 1 |
| D. | 0.72 |
| Answer» D. 0.72 | |
| 187. |
In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG __________ the absorption factor. |
| A. | Increases with increase in |
| B. | Is one at unity value of |
| C. | Both A and B |
| D. | Neither A nor B |
| Answer» D. Neither A nor B | |
| 188. |
If the specific heats of a gas and a vapor are 0.2KJ/Kg.°K and 1.5 KJ/Kg.°K respectively, and the humidity is 0.01; the humid heat in KJ/°Kg. is |
| A. | 0.31 |
| B. | 0.107 |
| C. | 0.017 |
| D. | 0.215 |
| Answer» E. | |
| 189. |
Which of the following is not fixed by the process requirements, in the design of absorbers? |
| A. | Flow rate of the entering gas |
| B. | Composition of the entering liquid |
| C. | Terminal concentrations of gas stream |
| D. | None of these |
| Answer» E. | |
| 190. |
In continuous distillation, the internal reflux ratio (Ri) and the external reflux ratio (Re) are related as |
| A. | Ri = Re/(1 - Re) |
| B. | Ri = (1 - Re)/Re |
| C. | Ri = Re |
| D. | Ri = Re/(1 + Re) |
| Answer» E. | |
| 191. |
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. | |
| 192. |
Which of the following binary systems is an example of a maximum boiling azeotrope? |
| A. | Water-hydrochloric acid |
| B. | Acetone-carbon disulphide |
| C. | Water-ethyl alcohol |
| D. | N-heptane-n-octane |
| Answer» B. Acetone-carbon disulphide | |
| 193. |
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. | |
| 194. |
Which of the following processes is followed by unsaturated air (with dry bulb temperature 12°C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40°C? |
| A. | Humidification only |
| B. | Heating only |
| C. | Both heating and humidification |
| D. | Evaporative cooling |
| Answer» D. Evaporative cooling | |
| 195. |
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 | |
| 196. |
Humid volume is the total volume in m³ of 1 kg of |
| A. | Vapour laden gas at 1 atm. and room temperature |
| B. | Gas plus its accompanying vapour at 1 atm. and room temperature |
| C. | Gas plus its accompanying vapour at 1 atm. and gas temperature |
| D. | Vapour laden gas at 1 atm. and gas temperature |
| Answer» D. Vapour laden gas at 1 atm. and gas temperature | |
| 197. |
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 |
| A. | Higher dew point |
| B. | Higher absolute (specific) humidity |
| C. | Higher relative humidity |
| D. | Higher wet bulb temperature |
| Answer» D. Higher wet bulb temperature | |
| 198. |
According to Poiseuille's law, the permeability for gas flow through a capillary is proportional to (where, μ = gas viscosity) |
| A. | μ |
| B. | 1/μ |
| C. | √μ |
| D. | μ² |
| Answer» C. √μ | |
| 199. |
If moisture content of solid on dry basis is X, then the same on wet basis is |
| A. | X/(X + 1) |
| B. | X/(X - 1) |
| C. | (X + 1)/X |
| D. | (X - 1)/X |
| Answer» B. X/(X - 1) | |
| 200. |
Which of the following is an undesirable property in a tower packing? |
| A. | Large surface per unit volume |
| B. | Large free cross-section |
| C. | Low weight per unit volume |
| D. | Large weight of liquid retained |
| Answer» E. | |