McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 451. |
As complete saturation of an adsorbent is approached, the differential heat of adsrop-tion approaches |
| A. | That of normal condensation |
| B. | Integral heat of adsorption |
| C. | Zero |
| D. | None of these |
| Answer» A. That of normal condensation | |
| 452. |
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» B. Liquid film | |
| 453. |
Relative humidity is the ratio of the |
| A. | Partial pressure of the vapour to the vapour pressure of the liquid at room temperature |
| B. | Partial pressure of the vapour to the vapour pressure of the liquid at gas temperature |
| C. | Actual humidity to saturation humidity |
| D. | None of these |
| Answer» B. Partial pressure of the vapour to the vapour pressure of the liquid at gas temperature | |
| 454. |
In the absorption of ammonia in water, the main resistance to absorption is by the __________ phase. |
| A. | Liquid |
| B. | Gas |
| C. | Both (A) & (B) |
| D. | Neither (A) nor (B) |
| Answer» B. Gas | |
| 455. |
In paper industry, paper is dried in a __________ dryer. |
| A. | Tunnel |
| B. | Heated cylinder |
| C. | Conveyor |
| D. | Festoon |
| Answer» B. Heated cylinder | |
| 456. |
Tray spacing in a distillation column of dia 10-12 ft. used in petroleum refinery may be around __________ inches. |
| A. | 5 |
| B. | 30 |
| C. | 60 |
| D. | 100 |
| Answer» B. 30 | |
| 457. |
Which of the following plays an important role in problems of simultaneous heat and mass transfer? |
| A. | Lewis number |
| B. | Schmidt number |
| C. | Prandtl number |
| D. | Sherwood number |
| Answer» A. Lewis number | |
| 458. |
In a moderately sized packed absorption tower, channelling (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» C. > 8:1 | |
| 459. |
If f = moles of vapour present per mole of feed, then the slope of feed line is (McCabeThiele method) |
| A. | (1 - f)/f |
| B. | - (f - 1)/f |
| C. | -1/f |
| D. | -f/(1 - f) |
| Answer» C. -1/f | |
| 460. |
Pick out the wrong statement. |
| A. | The operating line always lies above the equilibrium solubility curve in case of a single component absorber |
| B. | The operating line always lies below the equilibrium solubility curve in case of a single component stripper |
| C. | The operating pressure in solvent extraction system should be below vapor pressures of all components |
| D. | The solubility of a particular gas in ideal solution in any solvent is always the same |
| Answer» C. The operating pressure in solvent extraction system should be below vapor pressures of all components | |
| 461. |
Mass transfer co-efficient of liquid is |
| A. | Affected more by temperature than that for gases |
| B. | Affected much less by temperature than that for gases |
| C. | Not affected by the temperature |
| D. | None of these |
| Answer» A. Affected more by temperature than that for gases | |
| 462. |
Heat sensitive materials with very high latent heat of vaporisation may be economically separated using |
| A. | Liquid extraction |
| B. | Distillation |
| C. | Evaporation |
| D. | Absorption |
| Answer» A. Liquid extraction | |
| 463. |
The reciprocal of stripping factor is termed as |
| A. | Selectivity index |
| B. | Relative volatility |
| C. | Absorption factor |
| D. | Murphree efficiency |
| Answer» C. Absorption factor | |
| 464. |
A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state, |
| A. | Composition of vapors and that of liquid do not vary throughout the column |
| B. | Reboiler load and condenser load are minimum |
| C. | The top and bottom compositions are unchanged with and without total reflux |
| D. | The top and bottom compositions correspond to the maximum enrichment available |
| Answer» D. The top and bottom compositions correspond to the maximum enrichment available | |
| 465. |
In distillation columns, the number of bubble caps per tray primarily depends upon the |
| A. | Allowable liquid velocity |
| B. | Allowable gas velocity |
| C. | Allowable gas and liquid velocities |
| D. | Feed composition |
| Answer» C. Allowable gas and liquid velocities | |
| 466. |
Batch tray dryers suffers from the disadvantage of |
| A. | High maintenance cost |
| B. | Non-uniform & low production rate |
| C. | High labour cost & low heat economy |
| D. | All 'a', 'b' & 'c' |
| Answer» C. High labour cost & low heat economy | |
| 467. |
For absorbing a sparingly soluble gas in a liquid |
| A. | Gas side mass transfer co-efficient should be increased |
| B. | Liquid side mass transfer co-efficient should be increased |
| C. | Liquid side mass transfer co-efficient should be decreased |
| D. | Mass tr |
| Answer» C. Liquid side mass transfer co-efficient should be decreased | |
| 468. |
Smoke is an example of |
| A. | Solid dispersed in liquid |
| B. | Solid dispersed in gas |
| C. | Liquid dispersed in gas |
| D. | Gas dispersed in liquid |
| Answer» B. Solid dispersed in gas | |
| 469. |
Low viscosity absorbent is preferred for reasons of |
| A. | Rapid absorption rates and good heat transfer characteristics |
| B. | Improved flooding characteristics |
| C. | Low pressure drop on pumping |
| D. | All (A), (B) and (C) |
| Answer» D. All (A), (B) and (C) | |
| 470. |
Pick out the wrong statement. |
| A. | Cellulose acetate membranes are used in dialysis process |
| B. | Elutriation process refers to when the soluble material is largely concentrated on the surface of an insoluble solid and is simply washed off by the solvent |
| C. | 'Cascade' means a group of stages interconnected so that various streams flow from one to another |
| D. | Zirconia probe is used for the humidity measurement |
| Answer» D. Zirconia probe is used for the humidity measurement | |
| 471. |
The wetted wall tower is used to determine |
| A. | Individual mass transfer co-efficient (M.T.C.) in gaseous system |
| B. | M.T.C. of individual components in a liquid-liquid system |
| C. | M.T.C. of liquid in liquid-gas system |
| D. | The overall M.T.C. of the system |
| Answer» A. Individual mass transfer co-efficient (M.T.C.) in gaseous system | |
| 472. |
Rotary dryers cannot handle __________ materials. |
| A. | Free flowing |
| B. | Dry |
| C. | Sticky |
| D. | Granular |
| Answer» C. Sticky | |
| 473. |
In a solution containing 0.30 Kg mole of solute and 600 kg of solvent, the molality is |
| A. | 0.50 |
| B. | 0.60 |
| C. | 1 |
| D. | 2 |
| Answer» A. 0.50 | |
| 474. |
Small dia distillation column can be a |
| A. | Packed column |
| B. | Sieve tray |
| C. | Bubble cap |
| D. | Any of these |
| Answer» A. Packed column | |
| 475. |
Prandtl number for water at 20°C is about |
| A. | 7 |
| B. | 70 |
| C. | 0.7 |
| D. | 150 |
| Answer» A. 7 | |
| 476. |
Relative volatility does not change appreciably with the change in |
| A. | Temperature |
| B. | Vapour pressure of either component |
| C. | Total pressure |
| D. | None of these |
| Answer» A. Temperature | |
| 477. |
The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is |
| A. | +ve |
| B. | -ve |
| C. | Zero |
| D. | None of these |
| Answer» A. +ve | |
| 478. |
A minimum boiling azeotrope is exemplified by |
| A. | Toluene-benzene |
| B. | Acetone-carbon disulphide |
| C. | Water-isobutyl alcohol |
| D. | None of these |
| Answer» B. Acetone-carbon disulphide | |
| 479. |
Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture. |
| A. | Bound |
| B. | Unbound |
| C. | Critical |
| D. | None of these |
| Answer» A. Bound | |
| 480. |
Which is the controlling factor for a drum drier? |
| A. | Diffusion |
| B. | Heat transfer |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» B. Heat transfer | |
| 481. |
1 kg of a saturated aqueous solution of a highly soluble component A at 60°C is cooled to 25°C. The solubility limits of A are (0.6 kgA/kg water) at 60°C and (0.2 kgA/kg water) at 25°C. The amount in kg of the crystals formed is: |
| A. | 0.4 |
| B. | 0.25 |
| C. | 0.2 |
| D. | 0.175 |
| Answer» C. 0.2 | |
| 482. |
Which of the following is not a continuous drier? |
| A. | Drum drier |
| B. | Spray drier |
| C. | Tunnel drier |
| D. | Tray drier |
| Answer» D. Tray drier | |
| 483. |
Pick out the wrong statement: |
| A. | Reboiler is not used in open steam distillation |
| B. | The separation of solutes of different molecular sizes in a liquid solution by use of a suitable membrane is called dialysis |
| C. | Freeze drying is used for the drying of fish |
| D. | Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition |
| Answer» D. Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition | |
| 484. |
In an operating distillation column, the |
| A. | Vapors and liquids are at their dew point and bubble point respectively |
| B. | Driving force for the liquid flow is its specific weight |
| C. | Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column |
| D. | Highest temperature is encountered at the top of the column |
| Answer» C. Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column | |
| 485. |
Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined by the measurement of the __________ of a fibre. |
| A. | Electrical resistance |
| B. | Thermal conductivity |
| C. | Strength |
| D. | None of these |
| Answer» A. Electrical resistance | |
| 486. |
As per Gilliland's equation, the diffusivity is |
| A. | Directly proportional to 'T 1.5' |
| B. | Inversely proportional to 'P' |
| C. | Dependent on the molecular volume & molecular weight of components |
| D. | All 'a', 'b' & 'c' |
| Answer» D. All 'a', 'b' & 'c' | |
| 487. |
Pick out the wrong statement. |
| A. | In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed |
| B. | In small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency |
| C. | For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 × 10-2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10-2m/s |
| D. | The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity |
| Answer» C. For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 × 10-2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10-2m/s | |
| 488. |
If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that |
| A. | The system comprises of partially miscible liquids |
| B. | The system comprises of miscible liquids |
| C. | The system comprises of an azeotrope |
| D. | On heating, a vapor phase will appear; while on cooling, a solid phase will appear |
| Answer» D. On heating, a vapor phase will appear; while on cooling, a solid phase will appear | |
| 489. |
Leaching of coffee from coffee beans is done by |
| A. | Hot water |
| B. | Hexane |
| C. | Lime water |
| D. | Dilute H2SO4 (hot) |
| Answer» A. Hot water | |
| 490. |
In case of an absorber, the operating |
| A. | Line always lies above the equilibrium curve |
| B. | Line always lies below the equilibrium curve |
| C. | Line can be either above or below the equilibrium curve |
| D. | Velocity is more than the loading velocity |
| Answer» A. Line always lies above the equilibrium curve | |
| 491. |
Desirable value of absorption factor in an absorber is |
| A. | 1 |
| B. | < 1 |
| C. | > 1 |
| D. | 0.5 |
| Answer» C. > 1 | |
| 492. |
Radioactive nuclear waste is treated in |
| A. | Mixer-settler extractor |
| B. | Rotating-disc contactor |
| C. | Pulsed column extractor |
| D. | Bollman extractor |
| Answer» C. Pulsed column extractor | |
| 493. |
In case of a desorber (stripper), the |
| A. | Operating line always lies above the equilibrium curve |
| B. | Operating line always lies below the equilibrium curve |
| C. | Temperature remains unaffected |
| D. | Temperature always increases |
| Answer» B. Operating line always lies below the equilibrium curve | |
| 494. |
In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalent to a theoretical plate HTUOG = overall gas phase height of a transfer unit). |
| A. | Straight |
| B. | Parallel |
| C. | Both (A) & (B) |
| D. | Neither (A) nor (B) |
| Answer» C. Both (A) & (B) | |
| 495. |
Make up water is required in a cooling tower to replace the water lost by |
| A. | Evaporation |
| B. | Drift |
| C. | Blowdown and leakage |
| D. | All (A), (B) and (C) |
| Answer» D. All (A), (B) and (C) | |
| 496. |
Langmuir equation is associated with |
| A. | Leaching |
| B. | Adsorption |
| C. | Steam distillation |
| D. | Multi-component absorption |
| Answer» B. Adsorption | |
| 497. |
A packed tower compared to a plate tower for a particular mass transfer operation |
| A. | Incurs smaller pressure drop |
| B. | Allows installation of cooling coils |
| C. | Is less costly when built in large sizes/diameters |
| D. | Is more suitable, if suspended solids are present in fluid streams |
| Answer» A. Incurs smaller pressure drop | |
| 498. |
Which of the following is an undesirable property for an absorbing solvent? |
| A. | Low vapour pressure |
| B. | Low velocity |
| C. | Low freezing point |
| D. | None of these |
| Answer» D. None of these | |
| 499. |
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» C. Both (A) and (B) | |
| 500. |
Raoult's law applies to the |
| A. | All liquid solutions |
| B. | Non-ideal solution only |
| C. | Non-volatile solute |
| D. | Solvents |
| Answer» D. Solvents | |
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