McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 301. |
Dry bulb temperature of the gas is __________ the wet bulb temperature. |
| A. | Less than |
| B. | More than |
| C. | Equal to |
| D. | None of these |
| Answer» B. More than | |
| 302. |
__________ column is used in gas absorption process. |
| A. | Wetted wall |
| B. | Sieve/perforated tray |
| C. | Bubble cap |
| D. | Packed |
| Answer» D. Packed | |
| 303. |
The equilibrium liquid composition compared to the vapor composition in case of Azeotropic mixture is |
| A. | More |
| B. | Less |
| C. | Same |
| D. | Either more or less; depends on the system |
| Answer» C. Same | |
| 304. |
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» A. 2.09 × 10-4 | |
| 305. |
Unsaturated air (with dry bulb temperature and dew point being 35°C and 18°C respectively) is passed through a water spray chamber maintained at 15°C. The air will be cooled |
| A. | And humidified |
| B. | And dehumidified with increase in wet bulb temperature |
| C. | At the same relative humidity |
| D. | And dehumidified with decrease in wet bulb temperature |
| Answer» D. And dehumidified with decrease in wet bulb temperature | |
| 306. |
The 'shanks system' of leaching (i.e., counter-current multiple contact leaching) is used for |
| A. | Recovery of tannis from the tree barks and woods |
| B. | Leaching sodium nitrate from Chilean nitrate bearing rock |
| C. | Both (A) and (B) |
| D. | Neither (A) nor (B) |
| Answer» C. Both (A) and (B) | |
| 307. |
The value of Lewis number (Le = Sc/Pr) for air-water vapour system is around |
| A. | 1 |
| B. | 0.24 |
| C. | 3.97 |
| D. | 600 |
| Answer» A. 1 | |
| 308. |
Which of the following employs an accessory known as 'drift eliminator'? |
| A. | Multiple effect evaporator |
| B. | Mechanical draft cooling tower |
| C. | Rotary dryer |
| D. | Rotating disc contactor |
| Answer» B. Mechanical draft cooling tower | |
| 309. |
Dew point of an air-water vapor mixture |
| A. | Decreases with decrease in pressure |
| B. | At constant humidity & total pressure is fixed |
| C. | Corresponding to any point on the humidity chart is obtained by projecting a line through this point parallel to the temperature axis and to the saturation curve |
| D. | All 'a', 'b' & 'c' |
| Answer» D. All 'a', 'b' & 'c' | |
| 310. |
The term "approach" in a cooling tower refers to the difference in the temperature of the |
| A. | Cold water leaving the tower and the wet bulb temperature of the surrounding air |
| B. | Hot water entering the tower and the wet bulb temperature of the surrounding air |
| C. | Hot water entering and the cooled water leaving the cooling tower |
| D. | None of these |
| Answer» A. Cold water leaving the tower and the wet bulb temperature of the surrounding air | |
| 311. |
The relation, Sc = Pr = 1, is valid, when the mechanism of __________ transfer is same. |
| A. | Heat and mass |
| B. | Mass and momentum |
| C. | Heat and momentum |
| D. | Heat, momentum and mass |
| Answer» A. Heat and mass | |
| 312. |
McCabe-Thiele method |
| A. | Uses molal units for material and energy balance |
| B. | Uses weight fractions to express liquid and vapour composition |
| C. | Can use any type of units |
| D. | Is more accurate than Ponchon-Savarit method |
| Answer» A. Uses molal units for material and energy balance | |
| 313. |
If the path of liquid across the plate is very long as in case of large diameter tower, Murphree efficiency can be __________ percent. |
| A. | 100 |
| B. | > 100 |
| C. | < 100 |
| D. | None of these |
| Answer» B. > 100 | |
| 314. |
Humid volume, at a given temperature is a/an __________ function of humidity. |
| A. | Inverse |
| B. | Exponential |
| C. | Linear |
| D. | Logarithmic |
| Answer» C. Linear | |
| 315. |
If the specific heats of a gas and a vapor are 0.2KJ/Kg.°K and 1.5 KJ/Kg.°K respectively, and the humidity is 0.01; the humid heat in KJ/°Kg. is |
| A. | 0.31 |
| B. | 0.107 |
| C. | 0.017 |
| D. | 0.215 |
| Answer» D. 0.215 | |
| 316. |
Flooding in a vapor-liquid contacting equipment occurs in a tray, when the pressure drop through a tray is __________ the liquid head available in the downcomer. |
| A. | Less than |
| B. | More than |
| C. | Same as |
| D. | Very much less |
| Answer» B. More than | |
| 317. |
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» C. Extractive | |
| 318. |
Pick out the wrong statement. |
| A. | Packed towers are preferred for vacuum operation, because the pressure drop through the packing is less and they (packings) also lessen the possibility of tower wall collapse |
| B. | Packed towers are preferred over plate towers for handling corrosive and foamy liquids |
| C. | Diameter of randomly packed tower is normally more than 1.2 metres |
| D. | Due to uneven supply and improper distribution of liquid, problem of channelling, loading & flooding is generally encountered in packed towers |
| Answer» C. Diameter of randomly packed tower is normally more than 1.2 metres | |
| 319. |
Moisture contained by a substance in excess of the equilibrium moisture is called the __________ moisture. |
| A. | Unbound |
| B. | Free |
| C. | Critical |
| D. | Bound |
| Answer» B. Free | |
| 320. |
Which of the following is an undesirable characteristic for the solvent used in gas absorption? |
| A. | Low vapor pressure |
| B. | Low viscosity |
| C. | High gas solubility |
| D. | None of these |
| Answer» D. None of these | |
| 321. |
Hypersorption refers to a __________ process. |
| A. | Fixed bed absorption |
| B. | Moving bed absorption |
| C. | Fixed bed adsorption |
| D. | Moving bed adsorption |
| Answer» D. Moving bed adsorption | |
| 322. |
Drying of refractory is normally carried out in a __________ dryer. |
| A. | Open pan |
| B. | Tray |
| C. | Rotary vacuum |
| D. | Truck/tunnel |
| Answer» D. Truck/tunnel | |
| 323. |
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» A. Increase | |
| 324. |
In case of liquids, the binary diffusivity is proportional to (where, T = temperature) |
| A. | T |
| B. | √T |
| C. | T 2 |
| D. | 1/T |
| Answer» A. T | |
| 325. |
A liquid mixture contains 30% o-xylene, 60% p-xylene and 10%. m-xylene (all percentages in w/w). Which of the following statements would be true in respect of this mixture? |
| A. | The mixture exhibits an azeotrope at 101.3 kPa |
| B. | The composition of the mixture, in percent by volume is: o-xylene 30, p-xylene 60. and m- xylene 10 |
| C. | The composition of the mixture in mole percent is: o-xylene 30, p-xylene 60 and m-xyoene 10 |
| D. | The mixture contain optical isomers |
| Answer» A. The mixture exhibits an azeotrope at 101.3 kPa | |
| 326. |
The relative saturation of an unsaturated mixture of gas and vapor is independent of the |
| A. | Nature of the vapor |
| B. | Temperature of the mixture |
| C. | Composition of the mixture |
| D. | None of these |
| Answer» D. None of these | |
| 327. |
In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of |
| A. | Area between operating line and 45° diagonal x-y diagram |
| B. | Condenser and reboiler surfaces |
| C. | Tower cross-section |
| D. | None of these |
| Answer» A. Area between operating line and 45° diagonal x-y diagram | |
| 328. |
Advantage of continuous drying over batch drying is that the |
| A. | Drying cost per unit weight of dried product is less |
| B. | Product with more uniform moisture content is produced |
| C. | Equipment size required is smaller |
| D. | All 'a', 'b' & 'c' |
| Answer» D. All 'a', 'b' & 'c' | |
| 329. |
Which of the following assumes constant molal vaporisation and overflow? |
| A. | McCabe-Thiele method |
| B. | Ponchan-Savarit method |
| C. | Enthalpy concentration method |
| D. | Plate absorption column |
| Answer» A. McCabe-Thiele method | |
| 330. |
An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapour/kg of dry air is: |
| A. | 0.048 |
| B. | 0.079 |
| C. | 0.122 |
| D. | 0.152 |
| Answer» D. 0.152 | |
| 331. |
Which of the following binary systems is an example of a maximum boiling azeotrope? |
| A. | Water-hydrochloric acid |
| B. | Acetone-carbon disulphide |
| C. | Water-ethyl alcohol |
| D. | n-heptane-n-octane |
| Answer» A. Water-hydrochloric acid | |
| 332. |
For an absorber, both equilibrium and operating line will be straight for |
| A. | Concentrated solution and non-isothermal operation |
| B. | Dilute solution and non-isothermal operation |
| C. | Dilute solution and isothermal operation |
| D. | Concentrated solution and isothermal operation |
| Answer» C. Dilute solution and isothermal operation | |
| 333. |
Channelling is most severe |
| A. | In towers packed with stacked packing |
| B. | In towers packed randomly with crushed solids |
| C. | In dumped packing of regular units |
| D. | At very high liquid flow rate |
| Answer» A. In towers packed with stacked packing | |
| 334. |
Penetration model (theory) for mass transfer was enunciated by |
| A. | Danckwerts |
| B. | Toor and Marcello |
| C. | Higbie |
| D. | Kissinevskii |
| Answer» C. Higbie | |
| 335. |
Pick out the correct statement. |
| A. | Bound moisture is removed during constant rate drying period |
| B. | Free moisture is removed during falling rate drying period |
| C. | The sum of free moisture and equilibrium moisture in a solid is called the critical moisture |
| D. | The driving force for mass tr |
| Answer» A. Bound moisture is removed during constant rate drying period | |
| 336. |
Milk is dried usually in a __________ dryer. |
| A. | Freeze |
| B. | Spray |
| C. | Tray |
| D. | Rotary |
| Answer» B. Spray | |
| 337. |
Extraction of coffee from its seed is done by |
| A. | Liquid-liquid extraction |
| B. | Leaching |
| C. | Extractive distillation |
| D. | Steam distillation |
| Answer» B. Leaching | |
| 338. |
Unit of molal diffusivity is |
| A. | cm2/sec gm . mole |
| B. | gm moles/cm2 . sec |
| C. | gm moles/cm. sec |
| D. | gm moles/cm2. sec |
| Answer» C. gm moles/cm. sec | |
| 339. |
When the liquid phase and vapour phase of a binary system obeys Raoult's and Dalton's law respectively, the relative volatility is the ratio of |
| A. | Vapour pressure of component A to that of component B |
| B. | Vapour pressure of component A to the total pressure |
| C. | Vapour pressure of component A to the partial pressure of A |
| D. | Partial pressure of component A to the total pressure |
| Answer» A. Vapour pressure of component A to that of component B | |
| 340. |
In case of non-ideal gases and liquids, the molal diffusivity |
| A. | Varies inversely as the pressure |
| B. | Varies directly as the pressure |
| C. | Is independent of pressure |
| D. | Is equal to the volumetric diffusivity |
| Answer» C. Is independent of pressure | |
| 341. |
Flooding in a column results due to |
| A. | High pressure drop |
| B. | Low pressure drop |
| C. | Low velocity of the liquid |
| D. | High temperature |
| Answer» A. High pressure drop | |
| 342. |
Which of the following is a suitable absorbent for removal of H2S from natural gas? |
| A. | Vetrocoke solution |
| B. | Monoethanolamine (MEA) |
| C. | Dilute |
| D. | Hot water |
| Answer» B. Monoethanolamine (MEA) | |
| 343. |
Raoult's law is applicable to the |
| A. | Ideal solutions |
| B. | Real solutions |
| C. | Mixture of water and alcohol |
| D. | Non-ideal gases |
| Answer» A. Ideal solutions | |
| 344. |
Humid volume is the total volume in m3 of 1 kg of |
| A. | Vapour laden gas at 1 atm. and room temperature |
| B. | Gas plus its accompanying vapour at 1 atm. and room temperature |
| C. | Gas plus its accompanying vapour at 1 atm. and gas temperature |
| D. | Vapour laden gas at 1 atm. and gas temperature |
| Answer» C. Gas plus its accompanying vapour at 1 atm. and gas temperature | |
| 345. |
Calcium ammonium nitrate (a fertiliser) is dried in a __________ dryer. |
| A. | Rotary |
| B. | Vacuum |
| C. | Tunnel |
| D. | Tray |
| Answer» A. Rotary | |
| 346. |
Components, having widely different boiling point in a binary mixture, can be separated using __________ distillation. |
| A. | Molecular |
| B. | Extractive |
| C. | Steam |
| D. | Simple |
| Answer» D. Simple | |
| 347. |
Pick out the system with minimum boiling azeotrope at 1 atm. |
| A. | Benzene-toluene |
| B. | Ethyl alcohol-water |
| C. | Hydrochloric acid-water |
| D. | All (A), (B) and (C) |
| Answer» B. Ethyl alcohol-water | |
| 348. |
Unsaturated air (with dry bulb and wet bulb temperatures being 45°C and 25°C respectively) is passed through a water spray chamber maintained at 23°C. The air will be cooled and |
| A. | Humidified with wet bulb temperature decreasing |
| B. | Humidified at constant wet bulb temperature |
| C. | Dehumidified |
| D. | None of these |
| Answer» A. Humidified with wet bulb temperature decreasing | |
| 349. |
The film penetration model of mass transfer was enunciated by |
| A. | Gilliland |
| B. | Toor and Marcello |
| C. | Stefan |
| D. | Fick |
| Answer» B. Toor and Marcello | |
| 350. |
Equilibrium moisture of a solid is equal to the total moisture minus free moisture. Which of the following substances will have maxi-mum equilibrium moisture? |
| A. | Anthracite coal |
| B. | Rag paper |
| C. | Bamboo |
| D. | Inorganic solids |
| Answer» C. Bamboo | |
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