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.
| 251. |
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 |
| A. | gas film |
| B. | liquid film |
| C. | liquid-gas interface |
| D. | none of these |
| Answer» C. liquid-gas interface | |
| 252. |
During constant rate period, the rate of drying decreases with the |
| A. | decrease in air temperature |
| B. | increase in air humidity |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 253. |
In Mcabe-Thiele method, at infinite reflux ratio |
| A. | number of plates is maximum. |
| B. | overhead product is maximum. |
| C. | both the operating lines coincide with the diagram. |
| D. | none of these. |
| Answer» D. none of these. | |
| 254. |
Adsorption is an unit operation which generally involves __________ systems. |
| A. | liquid-solid |
| B. | gas-solid |
| C. | fluid-solid |
| D. | solid-solid |
| Answer» D. solid-solid | |
| 255. |
In case of non-ideal gases and liquids, the molal diffusivity |
| A. | varies inversely as the pressure. |
| B. | varies directly as the pressure. |
| C. | is independent of pressure. |
| D. | is equal to the volumetric diffusivity. |
| Answer» D. is equal to the volumetric diffusivity. | |
| 256. |
When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption. |
| A. | always lower than |
| B. | always higher than |
| C. | same as |
| D. | dependent on the system; can be either lower or higher than |
| Answer» B. always higher than | |
| 257. |
McCabe-Thiele method |
| A. | uses molal units for material and energy balance. |
| B. | uses weight fractions to express liquid and vapour composition. |
| C. | can use any type of units. |
| D. | is more accurate than Ponchan-Savarit method. |
| Answer» B. uses weight fractions to express liquid and vapour composition. | |
| 258. |
In the desorption of highly soluble gas from the liquid, the main resistance will be in the __________ phase. |
| A. | gas |
| B. | liquid |
| C. | both (a) & (b) |
| D. | neither (a) nor (b) |
| Answer» C. both (a) & (b) | |
| 259. |
__________ is the temperature at which a gas-vapor mixture becomes saturated, when cooled at constant total pressure out of contact with a liquid. |
| A. | Dew point |
| B. | Bubble point |
| C. | Dry bulb temperature |
| D. | Wet bulb temperature |
| Answer» B. Bubble point | |
| 260. |
For which of the following unit operations, Lewis number is of significance ? |
| A. | Adsorption |
| B. | Binary distillation |
| C. | Gas absorption |
| D. | Humidification |
| Answer» E. | |
| 261. |
Sides of equilateral-triangular co-ordinates (on which ternary liquid system is plotted) represent |
| A. | a pure component. |
| B. | a binary mixture. |
| C. | a ternary mixture. |
| D. | partially miscible ternary system. |
| Answer» C. a ternary mixture. | |
| 262. |
Entrainer used in azeotropic distillation should |
| A. | form a low boiling azeotrope with one of the constituents of the mixture. |
| B. | form a new azeotrope of low relative volatility with one of the constituents of the mixture. |
| C. | have high latent heat of vaporisation. |
| D. | have high viscosity to provide high tray efficiency. |
| Answer» B. form a new azeotrope of low relative volatility with one of the constituents of the mixture. | |
| 263. |
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 | |
| 264. |
The equipment used in the extraction of highly corrosive radio active liquids is |
| A. | pulse column |
| B. | spray column |
| C. | mixer settler |
| D. | baffle tower |
| Answer» B. spray column | |
| 265. |
Very tall packed towers are divided into series of beds to |
| A. | reduce the overall pressure drop |
| B. | avoid channelling |
| C. | reduce liquid hold-up |
| D. | avoid flooding |
| Answer» C. reduce liquid hold-up | |
| 266. |
For the flow of gases through a capillary, with increase in temperature, the permeability __________ as per Knudsen law. |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | either (a) or (b); depends on the gas |
| Answer» B. decreases | |
| 267. |
The commonly used solvent in supercritical extraction is |
| A. | methyl ethyl ketone. |
| B. | water. |
| C. | carbon tetrachloride. |
| D. | carbon dioxide. |
| Answer» E. | |
| 268. |
The velocity, concentration and temperature boundary, for the boundary layer development on 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 | |
| 269. |
With increase in temperature, the rate of extraction in leaching (solid-liquid extraction system) |
| A. | increases |
| B. | decreases |
| C. | remains unaffected |
| D. | increases Linearly |
| Answer» B. decreases | |
| 270. |
Sand is dried in foundaries in a___drier. |
| A. | rotary |
| B. | fluidisedbed |
| C. | vacuum |
| D. | spray |
| Answer» C. vacuum | |
| 271. |
Channelling is most severe |
| A. | in towers packed with stacked packing. |
| B. | in towers packed randomly with crushed solids. |
| C. | in dumped packing of regular units. |
| D. | at very high liquid flow rate. |
| Answer» B. in towers packed randomly with crushed solids. | |
| 272. |
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 | |
| 273. |
__________ diffusion is used for separating the isotopes of methane. |
| A. | Thermal |
| B. | Pressure |
| C. | Concentration |
| D. | Force |
| Answer» B. Pressure | |
| 274. |
With increase in temperature, the leaching rate increases due to |
| A. | decreased liquid viscosity |
| B. | increased diffusivity |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 275. |
Powdery materials can be guarded against caking tendency on storage by |
| A. | providing irregular grain size. |
| B. | providing minimum percentage of voids. |
| C. | having maximum possible points of contact. |
| D. | none of these. |
| Answer» E. | |
| 276. |
Wet bulb and dry bulb temperatures becomes identical at __________ percent saturation curve. |
| A. | 100 |
| B. | 50 |
| C. | 78 |
| D. | none of these |
| Answer» B. 50 | |
| 277. |
Plate towers are preferred to packed towers, when large temperature changes are involved, because of the reason that the |
| A. | packing may be crushed due to thermal expansion/contraction of the components of the equipments. |
| B. | pressure drop in the equipment will be . very high. |
| C. | viscosity variation of the fluids may cause channeling/flooding. |
| D. | none of these. |
| Answer» B. pressure drop in the equipment will be . very high. | |
| 278. |
The recovery of pencillin from the acidified fermentation broth is done by |
| A. | distillation |
| B. | evaporation |
| C. | absorption |
| D. | liquid extraction |
| Answer» E. | |
| 279. |
Bound moisture is that liquid which exerts an equilibrium vapor pressure __________ that of the pure liquid at the given temperature. |
| A. | less than |
| B. | more than |
| C. | equal to |
| D. | either (o) or (b); depends on the solid |
| Answer» B. more than | |
| 280. |
Which of the following operations does not involve leaching ? |
| A. | Dissolving gold from ores. |
| B. | Dissolving pharmaceutical products from bark or roots. |
| C. | Dissolving sugar from the cells of the beet. |
| D. | Removing nicotine from its water solution by kerosene. |
| Answer» E. | |
| 281. |
The relative volatility of a binary mixture at the azeotropic composition is |
| A. | 1 |
| B. | > 1 |
| C. | 0 |
| D. | ‚àû |
| Answer» B. > 1 | |
| 282. |
Langmuir equation is associated with |
| A. | leaching |
| B. | adsorption |
| C. | steam distillation |
| D. | multicomponent absorption. |
| Answer» C. steam distillation | |
| 283. |
Moisture contained by a substance in excess of the equilibrium moisture is called the __________ moisture. |
| A. | unbound |
| B. | free |
| C. | critical |
| D. | bound |
| Answer» C. critical | |
| 284. |
Which of the following equipments is not used for liquid dispersion ? |
| A. | Wetted wall towers |
| B. | Packed towers |
| C. | Venturi scrubbers |
| D. | Agitated vessels |
| Answer» E. | |
| 285. |
For a single component absorber, the operating line is straight only when plotted in term of __________ units. |
| A. | partial pressure |
| B. | mole ratio |
| C. | mole fraction |
| D. | none of these |
| Answer» C. mole fraction | |
| 286. |
When the solvent dissolves very little of solute, then |
| A. | solvent of low latent heat of vaporisation should be used. |
| B. | solvent of low freezing point should be used. |
| C. | large quantity of solvent is required to extract the solute. |
| D. | very small quantity of solvent is required. |
| Answer» D. very small quantity of solvent is required. | |
| 287. |
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 | |
| 288. |
Pick out the system with minimum boiling azeotrope at 1 atm. |
| A. | benzene-toluene |
| B. | ethyl alcohol-water |
| C. | hydrochloric acid-water |
| D. | all (a), (b) and (c) |
| Answer» C. hydrochloric acid-water | |
| 289. |
With increase in temperature, the solubility of gases in liquids, at fixed pressure |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | either (a) or (b), depends on the system |
| Answer» C. remains same | |
| 290. |
Tower diameter may be decreased by |
| A. | using higher reflux ratio. |
| B. | use of increased tray spacing. |
| C. | increasing the liquid flow rate. |
| D. | increasing the vapour flow rate. |
| Answer» C. increasing the liquid flow rate. | |
| 291. |
The binary diffusivity in gases and liquids vary respectively as |
| A. | T3/2 and T |
| B. | T and T3/2 |
| C. | T and T3/2 |
| D. | T3/2 and T |
| Answer» B. T and T3/2 | |
| 292. |
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. | the product composition but not the fraction vaporised. |
| B. | the product composition as well as the fraction vaporised. |
| C. | the fraction vaporised but not the product composition. |
| D. | neither the product composition nor the fraction vaporised. |
| Answer» D. neither the product composition nor the fraction vaporised. | |
| 293. |
The most economical range of absorption factor is |
| A. | 0 to 0.5 |
| B. | 0 to 3 |
| C. | 1.25 to 2 |
| D. | 5 to 15 |
| Answer» D. 5 to 15 | |
| 294. |
The slope of 9-line is determined by the |
| A. | reflux ratio |
| B. | plate efficiency to be achieved |
| C. | thermal condition of the feed |
| D. | relative volatility. |
| Answer» D. relative volatility. | |
| 295. |
To remove all the moisture from a wet solid it requires exposure to __________ air. |
| A. | perfectly dry |
| B. | highly humid |
| C. | high temperature |
| D. | none of these |
| Answer» B. highly humid | |
| 296. |
Molecular seives are porous |
| A. | alumina. |
| B. | silica. |
| C. | synthetic zeolites crystals/metal alumino-silicates. |
| D. | none of these. |
| Answer» D. none of these. | |
| 297. |
Which of the following equipments is not used in liquid-liquid extraction ? |
| A. | Pachuka tank |
| B. | Agitated vessels |
| C. | Centrifugal extractors |
| D. | Packed towers |
| Answer» B. Agitated vessels | |
| 298. |
McCabe-Thiele method of binary distillation does not assume that the |
| A. | sensible heat changes are negligible compared with latent heat changes. |
| B. | molar latent heats of all components are equal. |
| C. | heat of mixing is negligible. |
| D. | none of these |
| Answer» E. | |
| 299. |
During sensible cooling process |
| A. | relative humidity decreases |
| B. | relative humidity increases |
| C. | wet bulb temperature decreases |
| D. | both (b) and (c) |
| Answer» E. | |
| 300. |
The surface renewal frequency in Danckwerts' model of mass transfer is given by (KL: mass transfer co-efficient) |
| A. | KL2.DA |
| B. | KL2.DA |
| C. | KL2/DA |
| D. | KL/DA2 |
| Answer» B. KL2.DA | |