McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 551. |
Gaseous diffusion co-efficient increases with increase in the |
| A. | Pressure |
| B. | Temperature |
| C. | Both (A) & (B) |
| D. | Neither (A) nor (B) |
| Answer» B. Temperature | |
| 552. |
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» B. A binary mixture | |
| 553. |
The rate of mass transfer is not dependent upon the |
| A. | Degree of dispersion of one fluid in the other |
| B. | Interfacial surface exposed between the phases |
| C. | Both (A) & (B) |
| D. | None of these |
| Answer» D. None of these | |
| 554. |
Air at a particular humidity is heated in a furnace. The new dew point |
| A. | Decreases |
| B. | Increases |
| C. | Depends on the extent of heating |
| D. | Remain unchanged |
| Answer» B. Increases | |
| 555. |
The rate of solid-liquid extraction is limited by the |
| A. | Phase change of the solute as it dissolves in the solvent |
| B. | Diffusion of the solute through the solvent in the pores to the outside of the particle |
| C. | Diffusion of the solute from the solution in contact with the particle to the main bulk of the solution |
| D. | All 'a', 'b' & 'c' |
| Answer» D. All 'a', 'b' & 'c' | |
| 556. |
In case of gases, the binary diffusivity is proportional to (where, P = pressure). |
| A. | P |
| B. | 1/P |
| C. | 1/√P |
| D. | √P |
| Answer» B. 1/P | |
| 557. |
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» C. The fraction vaporised but not the product composition | |
| 558. |
What is the reflux ratio at total reflux? |
| A. | Zero |
| B. | Infinity |
| C. | Unity |
| D. | Data insufficient |
| Answer» B. Infinity | |
| 559. |
The operating line for an absorber is curved, when plotted in terms of |
| A. | Mole fractions |
| B. | Mole ratios |
| C. | Partial pressure |
| D. | Mass fractions |
| Answer» C. Partial pressure | |
| 560. |
Which of the following is the most suitable for extraction in a system having very low density difference? |
| A. | Mixer-settler extractor |
| B. | Centrifugal extractor |
| C. | Pulsed extractor |
| D. | Packed extraction tower |
| Answer» B. Centrifugal extractor | |
| 561. |
(NSh/NRe.NSc) is termed in mass transfer operation as the |
| A. | Stanton number |
| B. | Peclet number |
| C. | Thermal diffusivity |
| D. | Momentum diffusivity |
| Answer» A. Stanton number | |
| 562. |
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» B. Liquid | |
| 563. |
Positive deviation from Raoult's law means a mixture whose total pressure is |
| A. | Greater than that computed for ideality |
| B. | Less than that computed for ideality |
| C. | Less than the sum of the vapour pressure of the components |
| D. | None of these |
| Answer» A. Greater than that computed for ideality | |
| 564. |
Flooding results in |
| A. | High tray efficiency |
| B. | Low tray efficiency |
| C. | High gas velocity |
| D. | Good contact between the fluids |
| Answer» B. Low tray efficiency | |
| 565. |
At minimum reflux ratio for a given separation |
| A. | Number of plates is zero |
| B. | Number of plates is infinity |
| C. | Minimum number of the theoretical plates is required |
| D. | Separation is most efficient |
| Answer» B. Number of plates is infinity | |
| 566. |
An ideal tower packing should not |
| A. | Have low weight per unit volume |
| B. | Have large surface area per unit volume |
| C. | Have large free cross-section |
| D. | Hold up large amount of liquid in the packing |
| Answer» D. Hold up large amount of liquid in the packing | |
| 567. |
Diffusion in concentrated solutions differs from that in dilute solutions, because of the change in the __________ with the concentration of the solution. |
| A. | Degree of ideality |
| B. | Viscosity |
| C. | Both 'a '& 'b' |
| D. | Neither 'a' nor 'b' |
| Answer» C. Both 'a '& 'b' | |
| 568. |
Make up water is supplied during cooling tower operation to compensate for water losses due to |
| A. | Evaporation |
| B. | Blowdown |
| C. | Entrainment |
| D. | All (A), (B) & (C) |
| Answer» D. All (A), (B) & (C) | |
| 569. |
The dimension of diffusivity is same as that of the |
| A. | Density |
| B. | Molal concentration |
| C. | Kinematic viscosity |
| D. | Velocity head |
| Answer» C. Kinematic viscosity | |
| 570. |
As the reflux ratio in a distillation column is increased from the minimum, the |
| A. | Slope of the operating line in stripping section decreases |
| B. | Number of plates decreases very slowly first and then more and more rapidly |
| C. | Total cost first decreases and then increases |
| D. | Liquid flow increases while the vapor flow decreases for a system |
| Answer» C. Total cost first decreases and then increases | |
| 571. |
Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for |
| A. | Constant molal overflow |
| B. | Total reflux |
| C. | Constant relative volatility |
| D. | All (A), (B) and (C) |
| Answer» D. All (A), (B) and (C) | |
| 572. |
Solvent used in extractive distillation |
| A. | Is of low volatility |
| B. | Forms a low boiling azeotrope |
| C. | Forms a high boiling azeotrope |
| D. | Does not alter the relative volatility of the original components |
| Answer» B. Forms a low boiling azeotrope | |
| 573. |
When the feed to a distillation column is a saturated liquid, slope of the feed line is |
| A. | Zero |
| B. | Unity |
| C. | Infinity |
| D. | None of these |
| Answer» C. Infinity | |
| 574. |
The absorption factor is defined as (where, L = liquid flow rate, G = gas flow rate and, m = slope of the equilibrium line). |
| A. | L/mG |
| B. | G/mL |
| C. | mL/G |
| D. | LG/m |
| Answer» A. L/mG | |
| 575. |
Chemisorption (chemical adsorption) is |
| A. | Same as "Van der Waals" adsorption |
| B. | Characterised by adsorption of heat |
| C. | An irreversible phenomenon |
| D. | A reversible phenomenon |
| Answer» C. An irreversible phenomenon | |
| 576. |
A mixture of 10% C6H6 vapour in air at 25°C and 750 mm Hg has a dew point of 20°C. Its dew point at 30°C and 700 mm Hg will be around __________ °C. |
| A. | 21.7 |
| B. | 20 |
| C. | 27.3 |
| D. | 18.7 |
| Answer» D. 18.7 | |
| 577. |
Inside the distillation column, the |
| A. | Driving force for the vapour flow is the pressure drop |
| B. | Liquids are not always at their bubble points |
| C. | Pressure increases gradually from bottom to the top of the column |
| D. | None of these |
| Answer» A. Driving force for the vapour flow is the pressure drop | |
| 578. |
Dry bulb temperature of unsaturated air is more than its __________ temperature. |
| A. | Dew point |
| B. | Wet bulb |
| C. | Both 'a' & 'b' |
| D. | Neither 'a' nor 'b' |
| Answer» C. Both 'a' & 'b' | |
| 579. |
Boiling point diagram is not affected by the ambient |
| A. | Pressure |
| B. | Humidity |
| C. | Temperature |
| D. | Both (B) and (C) |
| Answer» D. Both (B) and (C) | |
| 580. |
Total reflux in a distillation operation requires minimum |
| A. | Reboiler load |
| B. | Number of plates |
| C. | Condenser load |
| D. | All (A), (B) and (C) |
| Answer» B. Number of plates | |
| 581. |
Inside the distillation columns, the |
| A. | Highest temperatures is near the feed plate |
| B. | Driving force for the liquid flow is its weight |
| C. | Vapors are not always at their dew points |
| D. | All (A), (B) and (C) |
| Answer» B. Driving force for the liquid flow is its weight | |
| 582. |
An Azeotropic mixture is a __________ mixture. |
| A. | Binary |
| B. | Ternary |
| C. | Constant boiling point |
| D. | None of these |
| Answer» C. Constant boiling point | |
| 583. |
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» A. Integral heat of adsorption | |
| 584. |
The diffusivity (D) in a binary gas mixture is related to the temperature (T) as |
| A. | D ∝ T |
| B. | D ∝ T 0.5 |
| C. | D ∝ T 1.5 |
| D. | D ∝ T 2 |
| Answer» C. D ∝ T 1.5 | |
| 585. |
The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = __________ |
| A. | 1 |
| B. | 0.5 |
| C. | 10 |
| D. | 0 |
| Answer» A. 1 | |
| 586. |
At a fixed total pressure, humidity depends only on the |
| A. | Partial pressure of vapour in the mixture |
| B. | Heat capacity of the vapour |
| C. | Density of the vapour |
| D. | None of these |
| Answer» A. Partial pressure of vapour in the mixture | |
| 587. |
In extractive distillation, solvent is |
| A. | Added to alter the relative volatility of the mixture |
| B. | Of high volatility |
| C. | Present in overhead stream |
| D. | Of high viscosity to give high tray efficiency |
| Answer» A. Added to alter the relative volatility of the mixture | |
| 588. |
Pick out the wrong statement. |
| A. | The mole fraction of solute is directly proportional to the molality of a 'dilute' solution |
| B. | For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is nonlinear in the case of steady state unimolal unidirectional diffusion |
| C. | Azeotropes obey Raoult's law at all temperature |
| D. | The relative volatility of a binary mixture at the Azeotropic composition is 1 |
| Answer» C. Azeotropes obey Raoult's law at all temperature | |
| 589. |
During drying operation, it is easier to remove the __________ moisture. |
| A. | Equilibrium |
| B. | Critical |
| C. | Unbound |
| D. | Bound |
| Answer» C. Unbound | |
| 590. |
Which of the following quantities need not be fixed before starting the design of a cocurrent absorber? |
| A. | Heat gain or loss |
| B. | Flow rate of entering liquid |
| C. | Flow rate of gas |
| D. | None of these |
| Answer» B. Flow rate of entering liquid | |
| 591. |
Which of the following parameters remains almost constant during adiabatic saturation of unsaturated air? |
| A. | Dry bulb temperature |
| B. | Dew point |
| C. | Wet bulb temperature |
| D. | None of these |
| Answer» C. Wet bulb temperature | |
| 592. |
In an absorber, HETP does not vary with the |
| A. | Flow rate of liquid |
| B. | Flow rate of gas |
| C. | Type and size of packing |
| D. | None of these |
| Answer» D. None of these | |
| 593. |
Leaching of sugar from sugar beets is done by |
| A. | Hot water |
| B. | Hexane |
| C. | Dilute H2SO4 |
| D. | Lime water |
| Answer» A. Hot water | |
| 594. |
In case of liquid-liquid binary diffusion, diffusivity of one constituent into another is not dependent on the |
| A. | Temperature and pressure |
| B. | Concentration |
| C. | Nature of the constituents |
| D. | None of these |
| Answer» D. None of these | |
| 595. |
When the temperature and humidity of air is low, we usually use __________ draft cooling tower. |
| A. | Natural |
| B. | Forced |
| C. | Induced |
| D. | None of these |
| Answer» A. Natural | |
| 596. |
Water-ethyl alcohol solution can be concentrated (in respect of alcohol concentration) by __________ distillation. |
| A. | Atmospheric |
| B. | Vacuum |
| C. | High pressure |
| D. | None of these |
| Answer» B. Vacuum | |
| 597. |
In an interphase mass transfer process, the lesser the solubility of a given solute in a liquid, the higher are the chances that the transfer process will be |
| A. | Liquid phase resistance-controlled |
| B. | Gas phase resistance controlled |
| C. | Impossible |
| D. | Driven by a non-linear driving force |
| Answer» B. Gas phase resistance controlled | |
| 598. |
Percentage saturation is __________ the relative saturation. |
| A. | Always smaller than |
| B. | Always greater than |
| C. | Not related to |
| D. | None of these |
| Answer» A. Always smaller than | |
| 599. |
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» D. None of these | |
| 600. |
In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG __________ the absorption factor. |
| A. | Increases with increase in |
| B. | Is one at unity value of |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» C. Both (A) and (B) | |
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