McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 601. |
If a two phase system is in physical equilibrium; then it means that, the |
| A. | Escaping tendency of each component from the liquid phase to the vapor phase is exactly equal to that from vapor phase to liquid phase |
| B. | Temperature of the liquid phase is equal to that of the vapor phase |
| C. | Total pressure throughout the liquid phase is equal to that throughout the vapor phase |
| D. | All (A), (B) and (C) |
| Answer» D. All (A), (B) and (C) | |
| 602. |
Which of the following remains constant during evaporative cooling process with recirculated water supply? |
| A. | Relative humidity |
| B. | Partial pressure of vapour |
| C. | Wet bulb temperature |
| D. | None of these |
| Answer» C. Wet bulb temperature | |
| 603. |
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» A. Less | |
| 604. |
Solvent used in extractive distillation |
| A. | Changes the relative volatility of the original components |
| B. | Should be of high volatility |
| C. | Should form azeotropes with the original components |
| D. | All (A), (B) and (C) |
| Answer» A. Changes the relative volatility of the original components | |
| 605. |
The equipment frequently used for adiabatic humidification-cooling operation with recirculating liquid is |
| A. | Natural draft cooling tower |
| B. | Induced draft cooling tower |
| C. | Spray chamber |
| D. | None of these |
| Answer» C. Spray chamber | |
| 606. |
CO2 can be absorbed by |
| A. | Hot cupric oxide |
| B. | Heated charcoal |
| C. | Cold Ca(OH)2 |
| D. | Alumina |
| Answer» B. Heated charcoal | |
| 607. |
The Knudsen diffusivity is dependent on the |
| A. | Molecular velocity only |
| B. | Pore radius of the catalyst only |
| C. | Molecular mean free path only |
| D. | Molecular velocity and pore radius of the catalyst |
| Answer» D. Molecular velocity and pore radius of the catalyst | |
| 608. |
Critical humidity of a solid salt means the humidity |
| A. | Above which it will always become damp |
| B. | Below which it will always stay dry |
| C. | Both (A) and (B) |
| D. | Above Which it will always become dry and below which it will always stay damp |
| Answer» C. Both (A) and (B) | |
| 609. |
For a binary mixture with low relative volatility, continuous rectification to get pure products will require |
| A. | Low reflux ratio |
| B. | Less number of trays |
| C. | Small cross-section column |
| D. | High reflux ratio |
| Answer» D. High reflux ratio | |
| 610. |
Overall efficiency of the distillation column is |
| A. | The ratio of number of ideal plates to actual plates |
| B. | The ratio of number of actual plates to ideal plates |
| C. | Same as the Murphree efficiency |
| D. | Always more than the point efficiency |
| Answer» A. The ratio of number of ideal plates to actual plates | |
| 611. |
The binary diffusivity in gases does not depend upon the |
| A. | Pressure |
| B. | Temperature |
| C. | Nature of the components |
| D. | None of these |
| Answer» D. None of these | |
| 612. |
Diffusivity in concentrated solutions differs from that in dilute solutions, because of the changes in |
| A. | Viscosity with concentration |
| B. | Degree of ideality of the solution |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» C. Both (A) and (B) | |
| 613. |
The assumption made in Elis method in distillation is that enthalpy concentration lines of vapor and liquid are |
| A. | Parallel |
| B. | Straight |
| C. | Both parallel and straight |
| D. | Neither parallel nor straight |
| Answer» C. Both parallel and straight | |
| 614. |
For contacting a highly soluble gas with a liquid |
| A. | Bubble the gas through liquid |
| B. | Spray the liquid on gas stream |
| C. | Either (A) or (B) would suffice |
| D. | None of these |
| Answer» A. Bubble the gas through liquid | |
| 615. |
Which of the following remains constant during sensible cooling process? |
| A. | Specific humidity |
| B. | Partial pressure of vapour |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» C. Both (A) and (B) | |
| 616. |
In saturated gas, the |
| A. | Vapour is in equilibrium with the liquid at the gas temperature |
| B. | Vapour is in equilibrium with the liquid at the room temperature |
| C. | Partial pressure of vapour equals the vapour pressure of the liquid at room temperature |
| D. | None of these |
| Answer» A. Vapour is in equilibrium with the liquid at the gas temperature | |
| 617. |
In a counter-current extractor, as the axial mixing increases, the extraction efficiency |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | Depends on the pressure of the system |
| Answer» B. Decreases | |
| 618. |
At equilibrium the concentration of water in vapour phase (C*) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is |
| A. | 0.0 |
| B. | 0.2 |
| C. | 0.4 |
| D. | 1.0 |
| Answer» C. 0.4 | |
| 619. |
In case of absorption with exothermic reaction, for fluids having |
| A. | Pr = Sc; percentage change in heat and mass transfer flux will be the same for a given change in the degree of turbulence |
| B. | Pr = Sc = 1; total mass, momentum and thermal diffusivity will be the same |
| C. | Both (A) and (B) |
| D. | Pr = Sc; there won't be any change in heat and mass tr |
| Answer» C. Both (A) and (B) | |
| 620. |
Drying operation under vacuum is carried out to |
| A. | Dry those materials which have very high unbound moisture content |
| B. | Reduce drying temperature |
| C. | Increase drying temperature |
| D. | Dry materials having high bound moisture content |
| Answer» B. Reduce drying temperature | |
| 621. |
Sticky material can be dried in a __________ dryer. |
| A. | Tray |
| B. | Rotary |
| C. | Fluidised bed |
| D. | None of these |
| Answer» A. Tray | |
| 622. |
The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). |
| A. | √T |
| B. | T |
| C. | T1.5 |
| D. | T3 |
| Answer» B. T | |
| 623. |
The minimum number of theoretical plates is required for achieving a given separation in distillation column with |
| A. | No reflux |
| B. | Total reflux |
| C. | Zero reflux ratio |
| D. | Minimum reflux ratio |
| Answer» B. Total reflux | |
| 624. |
For which of the following unit operations, Lewis number is of significance? |
| A. | Adsorption |
| B. | Binary distillation |
| C. | Gas absorption |
| D. | Humidification |
| Answer» D. Humidification | |
| 625. |
Heat in BTU necessary to increase the temperature of 1 lb of gas and its accompanying vapour by 1°F is called the |
| A. | Latent heat |
| B. | Humid heat |
| C. | Specific heat |
| D. | Sensible heat |
| Answer» C. Specific heat | |
| 626. |
With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature). |
| A. | Increases |
| B. | Remains unchanged |
| C. | Decreases |
| D. | Decreases linearly |
| Answer» A. Increases | |
| 627. |
As the reflux ratio decreases, the |
| A. | Separation becomes more efficient |
| B. | Number of plates increases |
| C. | Column diameter increases |
| D. | None of these |
| Answer» B. Number of plates increases | |
| 628. |
Only small amount of evaporation of water produces large cooling effects because of its |
| A. | Large latent heat |
| B. | Low viscosity |
| C. | Small latent heat |
| D. | None of these |
| Answer» A. Large latent heat | |
| 629. |
Ion exchange process is similar to |
| A. | Absorption |
| B. | Adsorption |
| C. | Extraction |
| D. | Leaching |
| Answer» B. Adsorption | |
| 630. |
Physical absorption is |
| A. | An irreversible phenomenon |
| B. | A reversible phenomenon |
| C. | Accompanied by evolution of heat |
| D. | Both (B) and (C) |
| Answer» D. Both (B) and (C) | |
| 631. |
Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number. |
| A. | Schmidt |
| B. | Sherwood |
| C. | Peclet |
| D. | Stanton |
| Answer» A. Schmidt | |
| 632. |
If G = insoluble gas in gas stream and L = non-volatile solvent in liquid stream, then the slope of the operating line for the absorber is |
| A. | L/G |
| B. | G/L |
| C. | Always < 1 |
| D. | None of these |
| Answer» A. L/G | |
| 633. |
For achieving rapid drying rate in a spray dryer, the diameter of the particles in the feed should be in the range of __________ microns (1 mm = 1000 microns). |
| A. | 1-5 |
| B. | 10-60 |
| C. | 200-300 |
| D. | > 500 |
| Answer» B. 10-60 | |
| 634. |
Berl saddle made of carbon cannot be used for |
| A. | Alkalis |
| B. | SO2 |
| C. | H2SO4 |
| D. | Oxidising atmosphere |
| Answer» D. Oxidising atmosphere | |
| 635. |
Capacity of a rotary dryer depends on its |
| A. | rpm |
| B. | Inclination with ground surface |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» C. Both (A) and (B) | |
| 636. |
The most common packing used in industrial operations is __________ rings. |
| A. | Raschig |
| B. | Lessing |
| C. | Cross-partition |
| D. | Single spiral |
| Answer» A. Raschig | |
| 637. |
Refractory bricks are usually dried in a __________ dryer. |
| A. | Tray |
| B. | Tunnel |
| C. | Conveyor |
| D. | Festoon |
| Answer» B. Tunnel | |
| 638. |
Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate. |
| A. | Increases |
| B. | Decreases |
| C. | Does not affect |
| D. | Exponentially increases |
| Answer» B. Decreases | |
| 639. |
The binary diffusivity in gases at atmospheric conditions is about |
| A. | 10-9 cm/sec |
| B. | 10-1 cm2/sec |
| C. | 10-3 sec/cm |
| D. | 10-4 cm2/sec2 |
| Answer» B. 10-1 cm2/sec | |
| 640. |
For absorbers, high pressure drop results in |
| A. | Increased efficiency |
| B. | Decreased efficiency |
| C. | High operating cost |
| D. | Better gas liquid contact |
| Answer» C. High operating cost | |
| 641. |
__________ 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» A. Dew point | |
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