MCQOPTIONS
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MCQOPTIONS
This section includes 368 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
In aqua ammonia and Lithium bromide water absorption refrigeration systems, the refrigerants are respectively$? |
| A. | Water and water |
| B. | Water and lithium bromide |
| C. | Ammonia and lithium bromide |
| D. | Ammonia and water |
| Answer» E. | |
| 252. |
The lowest temperature during the cycle in a vapour compression system occurs after$? |
| A. | Compression |
| B. | Expansion |
| C. | Condensation |
| D. | Evaporation |
| Answer» E. | |
| 253. |
Which of the following refrigerants has lowest freezing point?$? |
| A. | Freon-12 |
| B. | NH3 |
| C. | CO2 |
| D. | Freon-22 |
| Answer» E. | |
| 254. |
In vapour compression cycle the condition of refrigerant is superheated vapour$? |
| A. | After passing through the condenser |
| B. | Before passing through the condenser |
| C. | After passing through the expansion or throttle valve |
| D. | Before entering the expansion valve |
| Answer» C. After passing through the expansion or throttle valve | |
| 255. |
Which of the following refrigerant has the maximum ozone depletion potential in the stratosphere?$? |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | Fluorine |
| Answer» E. | |
| 256. |
The cooling system used for supersonic aircrafts and rockets is$? |
| A. | Simple air cooling system |
| B. | Bootstrap air cooling system |
| C. | Reduced ambient air cooling system |
| D. | Regenerative air cooling system |
| Answer» E. | |
| 257. |
Air refrigerator works on$? |
| A. | Reversed Carnot cycle |
| B. | Bell Coleman cycle |
| C. | Both (A) and (B) |
| D. | None of these |
| Answer» D. None of these | |
| 258. |
The temperature of air recorded by a thermometer, when its bulb is surrounded by a wet cloth exposed to the air, is called$? |
| A. | Wet bulb temperature |
| B. | Dry bulb temperature |
| C. | Dew point temperature |
| D. | None of these |
| Answer» B. Dry bulb temperature | |
| 259. |
The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy diagram represents$? |
| A. | Condensation of the refrigerant vapour |
| B. | Evaporation of the refrigerant liquid |
| C. | Compression of the refrigerant vapour |
| D. | Metering of the refrigerant liquid |
| Answer» C. Compression of the refrigerant vapour | |
| 260. |
The specific humidity during humidification process$? |
| A. | Remains constant |
| B. | Increases |
| C. | Decreases |
| D. | None of these |
| Answer» C. Decreases | |
| 261. |
In vapour compression cycle the condition of refrigerant is superheated vapour? |
| A. | After passing through the condenser |
| B. | Before passing through the condenser |
| C. | After passing through the expansion or throttle valve |
| D. | Before entering the expansion valve |
| Answer» C. After passing through the expansion or throttle valve | |
| 262. |
The cooling system used for supersonic aircrafts and rockets is? |
| A. | Simple air cooling system |
| B. | Bootstrap air cooling system |
| C. | Reduced ambient air cooling system |
| D. | Regenerative air cooling system |
| Answer» E. | |
| 263. |
The lowest temperature during the cycle in a vapour compression system occurs after? |
| A. | Compression |
| B. | Expansion |
| C. | Condensation |
| D. | Evaporation |
| Answer» E. | |
| 264. |
Which of the following refrigerant has the maximum ozone depletion potential in the stratosphere?? |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | Fluorine |
| Answer» E. | |
| 265. |
Which of the following refrigerants has lowest freezing point?? |
| A. | Freon-12 |
| B. | NH3 |
| C. | CO2 |
| D. | Freon-22 |
| Answer» E. | |
| 266. |
The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy diagram represents? |
| A. | Condensation of the refrigerant vapour |
| B. | Evaporation of the refrigerant liquid |
| C. | Compression of the refrigerant vapour |
| D. | Metering of the refrigerant liquid |
| Answer» C. Compression of the refrigerant vapour | |
| 267. |
The temperature of air recorded by a thermometer, when its bulb is surrounded by a wet cloth exposed to the air, is called? |
| A. | Wet bulb temperature |
| B. | Dry bulb temperature |
| C. | Dew point temperature |
| D. | None of these |
| Answer» B. Dry bulb temperature | |
| 268. |
Air refrigerator works on? |
| A. | Reversed Carnot cycle |
| B. | Bell Coleman cycle |
| C. | Both (A) and (B) |
| D. | None of these |
| Answer» D. None of these | |
| 269. |
The specific humidity during humidification process? |
| A. | Remains constant |
| B. | Increases |
| C. | Decreases |
| D. | None of these |
| Answer» C. Decreases | |
| 270. |
Ammonia absorption refrigeration cycle requires? |
| A. | Very little work input |
| B. | Maximum work input |
| C. | Nearly same work input as for vapour compression cycle |
| D. | Zero work input |
| Answer» B. Maximum work input | |
| 271. |
In a psychrometric chart, specific humidity (moisture content) lines are? |
| A. | Vertical and uniformly spaced |
| B. | Horizontal and uniformly spaced |
| C. | Horizontal and non-uniformly spaced |
| D. | Curved lines |
| Answer» C. Horizontal and non-uniformly spaced | |
| 272. |
Which of the following is not a desirable property of a refrigerant?? |
| A. | High risibility with oil |
| B. | Low boiling point |
| C. | Good electrical conductor |
| D. | Large latent heat |
| Answer» D. Large latent heat | |
| 273. |
The dry bulb temperature lines, on the psychrometric chart are? |
| A. | Vertical and uniformly spaced |
| B. | Horizontal and uniformly spaced |
| C. | Horizontal and non-uniformly spaced |
| D. | Curved lines |
| Answer» B. Horizontal and uniformly spaced | |
| 274. |
For large tonnage (more than 200 TR) air-conditioning applications, the compressor recommended is? |
| A. | Reciprocating |
| B. | Rotating |
| C. | Centrifugal |
| D. | Screw |
| Answer» D. Screw | |
| 275. |
The C.O.P. of a Carnot refrigerator in winter will be _________ as compared to C.O.P. in summer.? |
| A. | Same |
| B. | Lower |
| C. | Higher |
| D. | None of these |
| Answer» D. None of these | |
| 276. |
In a reversed Brayton cycle, the heat is absorbed by the air during? |
| A. | Isentropic compression process |
| B. | Constant pressure cooling process |
| C. | Isentropic expansion process |
| D. | Constant pressure expansion process |
| Answer» E. | |
| 277. |
The mass of water vapour present in __________ is called absolute humidity.? |
| A. | 1 m3 of water |
| B. | 1 m3 of dry air |
| C. | 1 kg of wet air |
| D. | 1 kg of dry air |
| Answer» C. 1 kg of wet air | |
| 278. |
In aqua ammonia absorption refrigeration system, incomplete rectification leads to accumulation of water in? |
| A. | Condenser |
| B. | Evaporator |
| C. | Absorber |
| D. | None of these |
| Answer» B. Evaporator | |
| 279. |
In a refrigeration system, the expansion device is connected between the? |
| A. | Compressor and condenser |
| B. | Condenser and receiver |
| C. | Receiver and evaporator |
| D. | Evaporator and compressor |
| Answer» D. Evaporator and compressor | |
| 280. |
The thermostatic expansion valve is used in ________ type of evaporators.? |
| A. | Flooded |
| B. | DX coil |
| C. | Dry |
| D. | None of these |
| Answer» D. None of these | |
| 281. |
The central air conditioning system has ___________ overall efficiency as compared to individual systems.? |
| A. | Same |
| B. | Lower |
| C. | Higher |
| D. | None of these |
| Answer» D. None of these | |
| 282. |
The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T‚ÇÅ = Lowest absolute temperature, and T‚ÇÇ = Highest absolute temperature)$ |
| A. | T‚ÇÅ / (T‚ÇÇ - T‚ÇÅ) |
| B. | (T‚ÇÇ - T‚ÇÅ)/T‚ÇÅ |
| C. | (T‚ÇÅ - T‚ÇÇ)/T‚ÇÅ |
| D. | T‚ÇÇ/ (T‚ÇÇ - T‚ÇÅ) |
| Answer» B. (T‚Äö√á√á - T‚Äö√á√Ö)/T‚Äö√á√Ö | |
| 283. |
A refrigerating system operating on reversed Brayton refrigeration cycle is used for maintaining 250 K. If the temperature at the end of constant pressure cooling is 300 K and rise in the temperature of air in the refrigerator is 50 K, then the net work of compression will be (assume air as working substance with Cp = 1 kJ/kg) |
| A. | 25 kJ/kg |
| B. | 50 kJ/kg |
| C. | 100 kJ/kg |
| D. | 125 kJ/kg |
| Answer» C. 100 kJ/kg | |
| 284. |
In larger industrial and commercial reciprocating compression systems, refrigerant widely used is |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | R-12 |
| Answer» B. Carbon dioxide | |
| 285. |
The higher temperature in vapour compression cycle occurs at |
| A. | Receiver |
| B. | Expansion valve |
| C. | Evaporator |
| D. | Compressor discharge |
| Answer» E. | |
| 286. |
Reducing suction pressure in refrigeration cycle |
| A. | Lowers evaporation temperature |
| B. | Increases power required per ton of refrigeration |
| C. | Lowers compressor capacity because vapour is lighter |
| D. | All of the above |
| Answer» E. | |
| 287. |
For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then |
| A. | Bigger cabinet should be used |
| B. | Smaller cabinet should be used |
| C. | Perfectly tight vapour seal should be used |
| D. | Refrigerant with lower evaporation temperature should be used |
| Answer» D. Refrigerant with lower evaporation temperature should be used | |
| 288. |
The sensible heat factor during cooling and dehumidification process is given by (where h‚ÇÅ = Enthalpy of air entering the cooling coil, h‚ÇÇ = Enthalpy of air leaving the cooling coil, and hA = Enthalpy of air at the end of dehumidification process)$ |
| A. | (hA - h2)/ (h1 - h2) |
| B. | (h2 - hA)/ (h1 - h2) |
| C. | (h1 - h2)/ (hA - h2) |
| D. | (hA - h1)/ (h2 - h1) |
| Answer» B. (h2 - hA)/ (h1 - h2) | |
| 289. |
Environmental protection agencies advice against the use of chlorofluorocarbon refrigerants since |
| A. | These react with water vapour and cause acid rain |
| B. | These react with plants and cause greenhouse effect |
| C. | These react with oxygen and cause its depletion |
| D. | These react with ozone layer |
| Answer» E. | |
| 290. |
The temperature of ammonia after compression in a vapour compression system is |
| A. | 20 to 50°C |
| B. | 50 to 70°C |
| C. | 70 to 110°C |
| D. | None of these |
| Answer» D. None of these | |
| 291. |
One of the purposes of sub cooling the liquid refrigerant is to |
| A. | Reduce compressor overheating |
| B. | Reduce compressor discharge temperature |
| C. | Increase cooling effect |
| D. | Ensure that only liquid and not the vapour enters the expansion (throttling) valve |
| Answer» E. | |
| 292. |
In a bootstrap air evaporative cooling system, the evaporator is provided |
| A. | Between the combustion chamber and the first heat exchanger |
| B. | Between the first heat exchanger and the secondary compressor |
| C. | Between the secondary compressor and the second heat exchanger |
| D. | Between the second heat exchanger and the cooling turbine |
| Answer» E. | |
| 293. |
A valve which maintains a constant degree of superheat at the end of the evaporator coil, is called |
| A. | Automatic expansion valve |
| B. | High side float valve |
| C. | Thermostatic expansion valve |
| D. | Low side float valve |
| Answer» E. | |
| 294. |
In aircraft, air refrigeration Cycle is used because of |
| A. | Low weight per tonne of refrigeration |
| B. | High heat transfer rate |
| C. | Low temperature at high altitudes |
| D. | Higher coefficient of performance |
| Answer» B. High heat transfer rate | |
| 295. |
The capacity of a domestic refrigerator is in the range of |
| A. | 0.1 to 0.3 TR |
| B. | 1 to 3 TR |
| C. | 3 to 5 TR |
| D. | 5 to 7 TR |
| Answer» B. 1 to 3 TR | |
| 296. |
In a lithium bromide absorption refrigeration system |
| A. | Lithium bromide is used as a refrigerant and water as an absorbent |
| B. | Water is used as a refrigerant and lithium bromide as an absorbent |
| C. | Ammonia is used as a refrigerant and lithium bromide as an absorbent |
| D. | None of the above |
| Answer» C. Ammonia is used as a refrigerant and lithium bromide as an absorbent | |
| 297. |
A vapour absorption refrigeration system |
| A. | Gives noisy operation |
| B. | Gives quiet operation |
| C. | Requires little power consumption |
| D. | Cools below 0°C |
| Answer» C. Requires little power consumption | |
| 298. |
In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = Bypass factor) |
| A. | B.P.F. - 1 |
| B. | 1 - B. P.F. |
| C. | 1/ B.P.F. |
| D. | 1 + B.P.F. |
| Answer» C. 1/ B.P.F. | |
| 299. |
The total pressure exerted by the mixture of air and water vapour is equal to the sum of pressures which each constituent would exert, if it occupied the same space by itself. This statement is called |
| A. | Kinetic theory of gases |
| B. | Newton's law of gases |
| C. | Dalton's law of partial pressures |
| D. | Avogadro's hypothesis |
| Answer» D. Avogadro's hypothesis | |
| 300. |
Hydrogen is used in Electrolux refrigeration system so as to _________ the rate of evaporation of the liquid ammonia passing through the evaporator. |
| A. | Equalize |
| B. | Reduce |
| C. | Increase |
| D. | None of these |
| Answer» D. None of these | |