McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 351. |
(NRe . NSc) is termed in mass transfer operation as the __________ number. |
| A. | Stanton |
| B. | Sherwood |
| C. | Peclet |
| D. | None of these |
| Answer» C. Peclet | |
| 352. |
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» B. Decreases | |
| 353. |
With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux |
| A. | Increases |
| B. | Decreases |
| C. | Remain same |
| D. | May increase or decrease; depends on system |
| Answer» B. Decreases | |
| 354. |
HETP is numerically equal to HTU, only when the operating line |
| A. | Lies below the equilibrium line |
| B. | Lies above the equilibrium line |
| C. | And equilibrium lines are parallel |
| D. | Is far from the equilibrium line |
| Answer» C. And equilibrium lines are parallel | |
| 355. |
The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called |
| A. | Decoction |
| B. | Percolation |
| C. | Elutriation or elution |
| D. | None of these |
| Answer» C. Elutriation or elution | |
| 356. |
__________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower. |
| A. | Sherwood |
| B. | Stanton |
| C. | Lewis |
| D. | Peclet |
| Answer» C. Lewis | |
| 357. |
The recovery of penicillin from the acidified fermentation broth is done by |
| A. | Distillation |
| B. | Evaporation |
| C. | Absorption |
| D. | Liquid extraction |
| Answer» D. Liquid extraction | |
| 358. |
Drift in a cooling tower is |
| A. | The water entrained by the circulating air |
| B. | Dependent on the water lost by evaporation |
| C. | Desirable |
| D. | All (A), (B) & (C) |
| Answer» A. The water entrained by the circulating air | |
| 359. |
In McCabe-Thiele method, at infinite reflux ratio |
| A. | The overhead product is minimum |
| B. | Both the operating lines coincide with diagonal |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» A. The overhead product is minimum | |
| 360. |
Gaseous diffusivity at atmospheric pressure is of the order of __________ cm2/second. |
| A. | 1 |
| B. | 1 to 5 |
| C. | 5 to 10 |
| D. | > 10 |
| Answer» A. 1 | |
| 361. |
Absorption factor, for a fixed degree of absorption from a fixed amount of gas should be |
| A. | 1 |
| B. | > 1 |
| C. | < 1 |
| D. | ≤ 1 |
| Answer» B. > 1 | |
| 362. |
Pick out the wrong statement. |
| A. | With decrease in feed temperature, the number of plates required for binary distillation decreases for a given ‘L/V’ ratio |
| B. | The extraction per unit of total height for a short packed column is more effective than for a tall column, in case of liquid-liquid extraction |
| C. | Natural draft cooling towers are made of ferroconcrete and its cross-section is wider at the bottom |
| D. | Vander wall adsorption is also called chemisorption |
| Answer» D. Vander wall adsorption is also called chemisorption | |
| 363. |
Molarity is defined as the number of gm moles of solute per __________ of solvent. |
| A. | Litre |
| B. | kg |
| C. | gm |
| D. | c.c |
| Answer» A. Litre | |
| 364. |
If Rm is the minimum reflux ratio, the optimum reflux ratio may be around __________ Rm. |
| A. | 1.2 to 1.5 |
| B. | 2.5 to 3 |
| C. | 3 to 4 |
| D. | 5 |
| Answer» A. 1.2 to 1.5 | |
| 365. |
Adsorption is a unit operation which generally involves __________ systems. |
| A. | Liquid-solid |
| B. | Gas-solid |
| C. | Fluid-solid |
| D. | Solid-solid |
| Answer» C. Fluid-solid | |
| 366. |
Surface renewal model of mass transfer was enunciated by |
| A. | Toor and Marcello |
| B. | Fick |
| C. | Danckwerts |
| D. | Stefan |
| Answer» C. Danckwerts | |
| 367. |
Agitator is provided in a crystalliser for |
| A. | Avoiding deposition on cooler surfaces |
| B. | Formation of nuclei |
| C. | Crystal growth |
| D. | All (A), (B) and (C) |
| Answer» D. All (A), (B) and (C) | |
| 368. |
Which of the following adsorbent is used to decolourise yellow glycerine? |
| A. | Silica gel |
| B. | Alumina |
| C. | Fuller's earth |
| D. | Activated carbon |
| Answer» D. Activated carbon | |
| 369. |
Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of |
| A. | Mass diffusivity to momentum diffusivity |
| B. | Thermal diffusivity to mass diffusivity |
| C. | Momentum diffusivity to thermal diffusivity |
| D. | None of these |
| Answer» B. Thermal diffusivity to mass diffusivity | |
| 370. |
Binary distillation involves the mass transfer by __________ at the gas-liquid interface. |
| A. | Unidirectional diffusion from liquid to gas phase |
| B. | Unidirectional diffusion from gas to liquid phase |
| C. | Either 'a' or 'b' |
| D. | A counter diffusion at an almost equal molar rate |
| Answer» D. A counter diffusion at an almost equal molar rate | |
| 371. |
Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number. |
| A. | Sherwood |
| B. | Schmidt |
| C. | Peclet |
| D. | Stanton |
| Answer» A. Sherwood | |
| 372. |
Sand is dried in foundries in a _________drier. |
| A. | Rotary |
| B. | Fluidised bed |
| C. | Vacuum |
| D. | Spray |
| Answer» B. Fluidised bed | |
| 373. |
Cox chart is useful in the design of |
| A. | Distillation column |
| B. | Evaporator |
| C. | Dryer |
| D. | Crystalliser |
| Answer» A. Distillation column | |
| 374. |
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» C. 9 | |
| 375. |
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 tr |
| Answer» D. No amount of C is tr | |
| 376. |
Pick out the wrong statement pertaining to leaching. |
| A. | Fine solids cannot be leached in a Pachuca tank |
| B. | Door classifier can be used for leaching of coarse solids |
| C. | Vegetable seeds can be leached in either of Bollman extractor, Rotocel or Kennedy extractor |
| D. | Very high temperature is not needed for the leaching of sugar beet |
| Answer» A. Fine solids cannot be leached in a Pachuca tank | |
| 377. |
Azeotropism for ethyl alcohol-water system disappears by |
| A. | Increasing temperature |
| B. | Decreasing pressure |
| C. | Increasing pressure |
| D. | No means |
| Answer» B. Decreasing pressure | |
| 378. |
Ordinary diffusion process is also called __________ diffusion. |
| A. | Pressure |
| B. | Thermal |
| C. | Concentration |
| D. | Forced |
| Answer» C. Concentration | |
| 379. |
The falling rate period in the drying of a solid is characterised by |
| A. | Increase in rate of drying |
| B. | Increasing temperatures both on the surface and within the solid |
| C. | Decreasing temperatures |
| D. | None of these |
| Answer» B. Increasing temperatures both on the surface and within the solid | |
| 380. |
Decoction refers to the use of solvent |
| A. | At ambient temperature |
| B. | At its boiling point |
| C. | In its vapor form |
| D. | None of these |
| Answer» B. At its boiling point | |
| 381. |
Schmidt number and Lewis number for pure air at atmospheric conditions are respectively |
| A. | < 1 and ≈ 1 |
| B. | 1 and 0 |
| C. | > 1 and ≈ 1 |
| D. | 0 and ≈ 1 |
| Answer» A. < 1 and ≈ 1 | |
| 382. |
Out of the following gas-liquid contacting devices, for a given set of operating conditions, gas pressure drop is the least in __________ tower. |
| A. | Wetted wall |
| B. | Bubble cap |
| C. | Perforated tray |
| D. | Packed |
| Answer» A. Wetted wall | |
| 383. |
Pick out the correct statement. |
| A. | For identical gas flow rates, less pressure drop occurs through a plate tower than through a packed tower |
| B. | Plate column can handle greater liquid loads without flooding than packed column, but the liquid hold up is more in the case of plate column |
| C. | For the same duty, plate columns weigh less than packed columns |
| D. | All (A), (B) and (C) |
| Answer» D. All (A), (B) and (C) | |
| 384. |
The solvent used in liquid-liquid extraction should have __________ less than one. |
| A. | Selectivity |
| B. | Distribution co-efficient |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» D. Neither (A) nor (B) | |
| 385. |
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. | Mass transfer co-efficient |
| B. | Thermal diffusivity |
| C. | Kinematic viscosity |
| D. | Volumetric diffusivity |
| Answer» A. Mass transfer co-efficient | |
| 386. |
Pick out the wrong statement. |
| A. | Different solids have different equilibrium moisture curves |
| B. | Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele method of theoretical plate calculation for distillation column |
| C. | Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column |
| D. | Even a forced draft cooling tower cannot cool water below the wet bulb temperature |
| Answer» C. Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column | |
| 387. |
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» D. Agitated vessels | |
| 388. |
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» A. 0.25 | |
| 389. |
Molecular diffusion is caused by the |
| A. | Transfer of molecules from low concentration to high concentration region |
| B. | Thermal energy of the molecules |
| C. | Activation energy of the molecules |
| D. | Potential energy of the molecules |
| Answer» B. Thermal energy of the molecules | |
| 390. |
Liquid diffusivity is of the order of __________ cm2 /second. |
| A. | 0.01 |
| B. | 0.1 |
| C. | 10-5 to 10-6 |
| D. | > 1 |
| Answer» C. 10-5 to 10-6 | |
| 391. |
The diffusivity, DAB (for component A diffusing in B) is equal to the diffusivity DBA (for component B diffusing in A) for a binary mixture of |
| A. | Newtonian liquids |
| B. | Non-Newtonian liquids |
| C. | Ideal gases |
| D. | Real gases |
| Answer» C. Ideal gases | |
| 392. |
Can a cooling tower cool water below the wet bulb temperature of inlet air? |
| A. | Yes |
| B. | No |
| C. | Yes; but height of cooling tower will be prohibitively high |
| D. | Yes; but the air flow rate should be excessively high |
| Answer» B. No | |
| 393. |
The expression, ln(F/W) = ∫ xF xW [dx/y* - x)] is |
| A. | Differential distillation equation |
| B. | For NtoG in absorption for dilute mixture |
| C. | Slope of q-line in McCabe-Thiele method |
| D. | For relative volatility |
| Answer» A. Differential distillation equation | |
| 394. |
Wetted wall tower experiment determines the |
| A. | Molal diffusivity |
| B. | Volumetric co-efficient |
| C. | Mass transfer co-efficient |
| D. | None of these |
| Answer» C. Mass transfer co-efficient | |
| 395. |
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» A. p = P | |
| 396. |
If the overall efficiency and Murphree plate efficiency are equal, then both the equilibrium and operating lines are: |
| A. | Straight |
| B. | Parallel |
| C. | Both (A) & (B) |
| D. | Neither (A) nor (B) |
| Answer» C. Both (A) & (B) | |
| 397. |
JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by |
| A. | Nsh = 2 |
| B. | Nst = 2 |
| C. | Nsc = 2 |
| D. | None of these |
| Answer» A. Nsh = 2 | |
| 398. |
In liquid-liquid extraction, the number of phases at plait point is |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» A. 1 | |
| 399. |
Molecular sieves are porous |
| A. | Alumina |
| B. | Silica |
| C. | Synthetic zeolites crystals/metal alumino-silicates |
| D. | None of these |
| Answer» C. Synthetic zeolites crystals/metal alumino-silicates | |
| 400. |
Nitrobenzene (boiling point = 210.6°C) is steam distilled at 1 atm pressure. Nitrobenzene will distil off __________ °C. |
| A. | At < 100 |
| B. | At > 210.6 |
| C. | Between 100 and 210 |
| D. | None of these |
| Answer» A. At < 100 | |
Done Studing? Take A Test.
Great job completing your study session! Now it's time to put your knowledge to the test. Challenge yourself, see how much you've learned, and identify areas for improvement. Don’t worry, this is all part of the journey to mastery. Ready for the next step? Take a quiz to solidify what you've just studied.