MCQOPTIONS
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MCQOPTIONS
This section includes 35 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume of quiescent liquid, in which D is the diffusivity of solute, is |
| A. | D/a |
| B. | D/2a |
| C. | Proportional to D |
| D. | Dependent on the Reynolds number |
| Answer» E. | |
| 2. |
Cox chart, which is useful in the design of distillation column particularly for petroleum hydrocarbons, is a plot of (where, P = vapor pressure, T = temperature). |
| A. | log P vs. T |
| B. | log P vs. log T |
| C. | T vs. P |
| D. | P vs. log T |
| Answer» B. log P vs. log T | |
| 3. |
Wet bulb and dry bulb temperatures becomes identical at __________ percent saturation curve. |
| A. | 100 |
| B. | 50 |
| C. | 78 |
| D. | None of these |
| Answer» B. 50 | |
| 4. |
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» E. | |
| 5. |
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. | |
| 6. |
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 | |
| 7. |
In case of __________ distillation, a solvent is added to alter the relative volatility of the mixture to be separated. |
| A. | Molecular |
| B. | Azeotropic |
| C. | Extractive |
| D. | Flash |
| Answer» D. Flash | |
| 8. |
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» B. Thermal conductivity | |
| 9. |
A natural draft cooling tower is filled with wooden grids, which covers about __________ percent of the tower height. |
| A. | 10-15 |
| B. | 30-40 |
| C. | 70-80 |
| D. | 90-100 |
| Answer» B. 30-40 | |
| 10. |
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 | |
| 11. |
For turbulent mass transfer in pipes, the Sherwood number depends on the Reynolds number as |
| A. | Re0.33 |
| B. | Re0.53 |
| C. | Re0.83 |
| D. | Re |
| Answer» D. Re | |
| 12. |
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 | |
| 13. |
Which of the following gas-liquid contacting devices incurs the least pressure drop for a particular duty? |
| A. | Grid tray tower |
| B. | Perforated tray tower |
| C. | Wetted wall tower |
| D. | Bubble cap tower |
| Answer» E. | |
| 14. |
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 | |
| 15. |
Mass transfer co-efficient varies as DAB 0.5, according to the __________ theory. |
| A. | Film |
| B. | Surface renewal |
| C. | Penetration |
| D. | None of these |
| Answer» C. Penetration | |
| 16. |
At __________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation. |
| A. | Operating |
| B. | Total |
| C. | Minimum |
| D. | Maximum permissible |
| Answer» C. Minimum | |
| 17. |
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» E. | |
| 18. |
Fenske equation for determining the minimum number of theoretical stages in distillation column holds good, when the |
| A. | Relative volatility is reasonably constant |
| B. | Mixture (to be separated) shows negative deviation from ideality |
| C. | Mixture (to be separated) shows positive deviation from ideality |
| D. | Multi-component distillation is involved |
| Answer» B. Mixture (to be separated) shows negative deviation from ideality | |
| 19. |
For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will |
| A. | Increase |
| B. | Decrease |
| C. | Remain same |
| D. | Data insufficient, can't be predicted |
| Answer» B. Decrease | |
| 20. |
The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by |
| A. | Raising the temperature |
| B. | Lowering the total pressure |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» D. Neither (A) nor (B) | |
| 21. |
For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same. |
| A. | Unsaturated surface |
| B. | Constant rate |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» D. Neither (A) nor (B) | |
| 22. |
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» C. Pulsed extractor | |
| 23. |
The velocity, concentration and temperature boundary, for the boundary layer development on a flat plate during connective mass transfer will be same, if |
| A. | NSc = 1 |
| B. | NSc = NPr = NLe |
| C. | NPr = NLe |
| D. | NSc = NLe |
| Answer» C. NPr = NLe | |
| 24. |
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» D. Real gases | |
| 25. |
Liquid diffusivity is of the order of __________ cm2 /second. |
| A. | 0.01 |
| B. | 0.1 |
| C. | 10-5 to 10-6 |
| D. | > 1 |
| Answer» D. > 1 | |
| 26. |
For the flow of gases through a capillary, with increase in temperature, the permeability __________ as per Knudsen law. |
| A. | Increases |
| B. | Decreases |
| C. | Remain same |
| D. | Either (A) or (B); depends on the gas |
| Answer» B. Decreases | |
| 27. |
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» C. A ternary mixture | |
| 28. |
For continuous drying of granular or crystalline material, the dryer used is the __________ dryer. |
| A. | Tunnel |
| B. | Tray |
| C. | Rotary |
| D. | None of these |
| Answer» D. None of these | |
| 29. |
__________ 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» D. Peclet | |
| 30. |
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» B. Schmidt | |
| 31. |
With decrease in the throughput (compared with the design capacity) for a bubble cap distillation column, its efficiency |
| A. | Increases |
| B. | Decreases |
| C. | Remain same |
| D. | May increase or decrease; depends on individual design |
| Answer» B. Decreases | |
| 32. |
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» C. Both (A) & (B) | |
| 33. |
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 | |
| 34. |
The diffusion co-efficient in m2 /s. of acetic acid in benzene (liquid in liquid) is |
| A. | 2.09 10-4 |
| B. | 2.09 10-5 |
| C. | 2.09 10-9 |
| D. | 2.09 10-12 |
| Answer» B. 2.09 10-5 | |
| 35. |
For the case of flow of air past a wet bulb thermometer (air water vapour system), the approximate value of h2/ky .Cz is around |
| A. | 0.60 |
| B. | 0.24 |
| C. | 1 |
| D. | 0.72 |
| Answer» D. 0.72 | |