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.
| 351. |
Which of the following is an undesirable characteristic for the solvent used in gas absorption ? |
| A. | Low vapor pressure |
| B. | Low viscosity |
| C. | High gas solubility |
| D. | None of these |
| Answer» E. | |
| 352. |
For a binary mixture with low relative volatility, |
| A. | use steam distillation. |
| B. | use molecular distillation. |
| C. | use high pressure distillation. |
| D. | an azeotrope may be formed during distillation. |
| Answer» E. | |
| 353. |
For a binary mixture distillation process, the degree of freedom is 2. However, if the pressure is fixed in this process, the number of independent variables in this process will be |
| A. | 1 |
| B. | 0 |
| C. | 2 |
| D. | 3 |
| Answer» B. 0 | |
| 354. |
Blowdown in a cooling tower |
| A. | means discarding a small fraction of circulating water to prevent and limit the concentration of salt and impurities. |
| B. | increases the scale forming tendencies of water. |
| C. | is undesirable. |
| D. | all (a), (b) & (c). |
| Answer» B. increases the scale forming tendencies of water. | |
| 355. |
The partial pressure distribution of an ideal gas diffusing through another stagnant ideal gas at steady state follows a/an __________ law. |
| A. | exponential |
| B. | parabolic |
| C. | linear |
| D. | cubic |
| Answer» B. parabolic | |
| 356. |
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 | |
| 357. |
When the liquid phase and vapour phase of a binary system obeys Raoult's and Dalton's law respectively, the relative volatility is the ratio of |
| A. | vapour pressure of component A to that of component B. |
| B. | vapour pressure of component A to the total pressure. |
| C. | vapour pressure of component A to the partial pressure of A. |
| D. | partial pressure of component A to the total pressure. |
| Answer» B. vapour pressure of component A to the total pressure. | |
| 358. |
The minimum liquid rate to be used in an absorber corresponds to an operating line |
| A. | of slope = 1 |
| B. | ofslope = 0.1 |
| C. | tangential to the equilibrium curve |
| D. | none of these |
| Answer» D. none of these | |
| 359. |
The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or "outgassed" adsorbent to from a definite concentration of adsorbate is called its |
| A. | integral heat of adsorption. |
| B. | heat of wetting. |
| C. | differential heat of adsorption. |
| D. | heat of normal condensation. |
| Answer» B. heat of wetting. | |
| 360. |
With increase in the liquid flow rate at a fixed gas velocity in a randomly packed counter current gas-liquid absorption column, the gas pressure drop |
| A. | decreases |
| B. | remains unchanged |
| C. | increases |
| D. | decreases exponentially |
| Answer» D. decreases exponentially | |
| 361. |
Molecular diffusivity of a liquid |
| A. | increases with temperature. |
| B. | decreases with temperature. |
| C. | may increase or decrease with temperature. |
| D. | is independent of temperature. |
| Answer» B. decreases with temperature. | |
| 362. |
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. | |
| 363. |
Paper industry employs __________ driers. |
| A. | cylinder |
| B. | rotary |
| C. | spray |
| D. | fluidised bed |
| Answer» B. rotary | |
| 364. |
Stacked packing compared to dumped packing |
| A. | provides poorer contact between the fluids. |
| B. | gives lower pressure drop. |
| C. | both (a) and (b). |
| D. | gives higher pressure drop. |
| Answer» D. gives higher pressure drop. | |
| 365. |
The relative saturation of a partially saturated mixture of vapour and gas can be increased by __________ of the mixture. |
| A. | reducing the total pressure |
| B. | increasing the total pressure |
| C. | reducing the temperature |
| D. | both (b) and (c) |
| Answer» E. | |
| 366. |
In which of the following unit operations, the selectivity is an important parameter ? |
| A. | Distillation |
| B. | Solvent extraction |
| C. | Absorption |
| D. | None of these |
| Answer» C. Absorption | |
| 367. |
For the air water system under ambient conditions, the adiabatic saturation temperature and the wet bulb temperature are nearly equal, because |
| A. | water has a high latent heat of evaporation. |
| B. | Lewis number is close to unity. |
| C. | they are always equal under all circumstances. |
| D. | solubility of the components of air in water is very small. |
| Answer» B. Lewis number is close to unity. | |
| 368. |
Separation of the isotopes of helium for scientific investigations is done by |
| A. | reverse osmosis |
| B. | thermal diffusion |
| C. | leaching |
| D. | solvent extraction |
| Answer» C. leaching | |
| 369. |
With increase in temperature, the rate of leaching increases, because the |
| A. | diffusivity of solute increases. |
| B. | viscosity of solvent decreases. |
| C. | thermal conductivity of solute increases. |
| D. | none of these. |
| Answer» B. viscosity of solvent decreases. | |
| 370. |
The caking of crystals can be prevented by |
| A. | maintaining high critical humidity. |
| B. | maintaining low critical humidity. |
| C. | coating the product with inert material. |
| D. | both (a) and (c) |
| Answer» E. | |
| 371. |
Leaching of coffee from coffee beans is done by |
| A. | hot water |
| B. | hexane |
| C. | lime water |
| D. | dilute H2SO4 (hot) |
| Answer» B. hexane | |
| 372. |
For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is |
| A. | calculated |
| B. | unknown |
| C. | known |
| D. | not required |
| Answer» D. not required | |
| 373. |
Percentage saturation is __________ the relative saturation. |
| A. | always smaller than |
| B. | always greater than |
| C. | not related to |
| D. | none of these |
| Answer» B. always greater than | |
| 374. |
When the __________ the relative humidity of air decreases, despite an increase in the absolute humidity. |
| A. | temperature rises |
| B. | pressure rises |
| C. | temperature falls |
| D. | pressure falls |
| Answer» B. pressure rises | |
| 375. |
Heat sensitive materials like certain pharmaceuticals and food stuffs can be dried in a/an __________ dryer. |
| A. | indirect tray |
| B. | spray |
| C. | freeze |
| D. | none of these |
| Answer» D. none of these | |
| 376. |
Separation of a mixture of two gases by absorption in the liquid solvent depends upon the difference in their |
| A. | viscosity |
| B. | density |
| C. | solubility |
| D. | relative volatility |
| Answer» D. relative volatility | |
| 377. |
In an absorption coloumn, the flooding velocity for random packing is __________ that for stacked/regular packing. |
| A. | greater than |
| B. | smaller than |
| C. | equal to |
| D. | either (a), or (b) ; depends on the type of packing |
| Answer» C. equal to | |
| 378. |
In liquid extraction, if the selectivity is unity, then |
| A. | separation of the constituents is the most effective. |
| B. | no separation will occur. |
| C. | amount of solvent required will be minimum. |
| D. | solvent flow rate should be very low. |
| Answer» C. amount of solvent required will be minimum. | |
| 379. |
Flooding in a distillation column is detected by a sharp |
| A. | increase in Murphree plate efficiency. |
| B. | decrease in pressure drop. |
| C. | decrease in liquid hold up in the coloumn. |
| D. | increase in pressure drop. |
| Answer» E. | |
| 380. |
It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%). |
| A. | 15 min |
| B. | 51 min |
| C. | 71 min |
| D. | 94 min |
| Answer» D. 94 min | |
| 381. |
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. | |
| 382. |
Pick out the system with maximum boiling azeotrope at 1 atm. |
| A. | acetone chloroform |
| B. | ethyl alcohol-water |
| C. | benzene-ethyl alcohol |
| D. | none of these |
| Answer» B. ethyl alcohol-water | |
| 383. |
In a moderately sized packed absorption tower, channeling (which is most severe with stacked packings) can be minimised by taking the ratio of tower diameter to packing diameter |
| A. | > 4 :1 |
| B. | < 8 : 1 |
| C. | > 8:1 |
| D. | < 6:1 |
| Answer» D. < 6:1 | |
| 384. |
When the liquid over a plate is of uniform concentration, then |
| A. | Murphree efficiency > point efficiency. |
| B. | Murphree efficiency < point efficiency. |
| C. | Murphree efficiency = point efficiency. |
| D. | Murphree efficiency ≠ point efficiency. |
| Answer» D. Murphree efficiency ‚↠point efficiency. | |
| 385. |
According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity) |
| A. | D |
| B. | D2 |
| C. | D0.5 |
| D. | 1/D |
| Answer» B. D2 | |
| 386. |
The most efficient cooling tower out of the following is |
| A. | induced draft |
| B. | forced draft |
| C. | natural draft |
| D. | atmospheric |
| Answer» B. forced draft | |
| 387. |
The reciprocal of stripping factor is termed as |
| A. | selectivity index |
| B. | relative volatility |
| C. | absorption factor |
| D. | Murphree efficiency |
| Answer» D. Murphree efficiency | |
| 388. |
At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid __________ that in dry packed tower. |
| A. | is greater than |
| B. | is lower than |
| C. | is same as |
| D. | cannot be predicted as data are insufficient |
| Answer» B. is lower than | |
| 389. |
Unsaturated air (with dry bulb temperature and dew point being 35°C and 18°C respectively) is passed through a water spray chamber maintained at 15°C. The air will be cooled$ |
| A. | and humidified. |
| B. | and dehumidified with increase in wet bulb temperature. |
| C. | at the same relative humidity. |
| D. | and dehumidified with decrease in wet bulb temperature. |
| Answer» E. | |
| 390. |
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. | |
| 391. |
The vapour pressure exerted by the moisture contained in a wet solid depends upon the |
| A. | nature of the moisture. |
| B. | temperature. |
| C. | nature of the solid. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 392. |
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 | |
| 393. |
In physical terms, Schmidt number means |
| A. | thermal diffusivity/mass diffusivity. |
| B. | thermal diffusivity/momentum diffusivity. |
| C. | momentum diffusivity/mass diffusivity. |
| D. | mass diffusivity/thermal diffusivity. |
| Answer» D. mass diffusivity/thermal diffusivity. | |
| 394. |
The expression, y(1 - x)/x(1 - y) is for |
| A. | absorption factor |
| B. | relative volatility |
| C. | selectivity |
| D. | Murphree efficiency |
| Answer» C. selectivity | |
| 395. |
Stage efficiency in a leaching process depends on the |
| A. | time of contact between the solid and the solution |
| B. | rate of diffusion of the solute through the solid and into the liquid |
| C. | both (a) and (b) |
| D. | vapour pressure of the solution |
| Answer» D. vapour pressure of the solution | |
| 396. |
For gas absorption, low viscosity solvents are preferred, because of their |
| A. | better flow characteristics. |
| B. | low pumping pressure drop. |
| C. | rapid absorption rates. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 397. |
The value of L/mG ratio for economical absorption operation ranges from |
| A. | 0.5 to 0.8 |
| B. | 0.8 to 1.2 |
| C. | 1.25 to 2.0 |
| D. | 2.5 to 3.5 |
| Answer» D. 2.5 to 3.5 | |
| 398. |
In the constant rate period of the rate of drying curve for batch drying, |
| A. | cracks develop on the surface of the solid. |
| B. | rate of drying decreases abruptly. |
| C. | surface evaporation of unbound moisture occurs. |
| D. | none of these. |
| Answer» D. none of these. | |
| 399. |
The value of NA/(NA + NB) for steady state molecular diffusion of gas 'A' through non-diffusing gas 'B' is |
| A. | 1 |
| B. | ‚àû |
| C. | 0.5 |
| D. | 2 |
| Answer» B. ‚àû | |
| 400. |
In paper industry, paper is dried in a __________ dryer. |
| A. | tunnel |
| B. | heated cylinder |
| C. | conveyor |
| D. | festoon |
| Answer» C. conveyor | |