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.
| 201. |
_Which of the following refrigerant is highly toxic and flammable?$? |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | R-12 |
| Answer» B. Carbon dioxide | |
| 202. |
_The thermostatic expansion valve operates on the changes in the$? |
| A. | Degree of superheat at exit from the evaporator |
| B. | Temperature of the evaporator |
| C. | Pressure in the evaporator |
| D. | None of the above |
| Answer» B. Temperature of the evaporator | |
| 203. |
_The bypass factor of a cooling coil decreases with$? |
| A. | Decrease in fin spacing and increase in number of rows |
| B. | Increase in fin spacing and increase in number of rows |
| C. | Increase in fin spacing and decrease in number of rows |
| D. | Decrease in fin spacing and decrease in number of rows |
| Answer» B. Increase in fin spacing and increase in number of rows | |
| 204. |
_The ratio of heat extracted in the refrigerator to the work-done on the refrigerant is called$? |
| A. | Coefficient of performance of refrigeration |
| B. | Coefficient of performance of heat pump |
| C. | Relative coefficient of performance |
| D. | Refrigerating efficiency |
| Answer» B. Coefficient of performance of heat pump | |
| 205. |
_The leakage in a refrigeration system using Freon is detected by$? |
| A. | Halide torch |
| B. | Sulphur sticks |
| C. | Soap and water |
| D. | All of these |
| Answer» B. Sulphur sticks | |
| 206. |
_The reduced ambient air cooling system has$? |
| A. | One cooling turbine and one heat exchanger |
| B. | One cooling turbine and two heat exchangers |
| C. | Two cooling turbines and one heat exchanger |
| D. | Two cooling turbines and two heat exchangers |
| Answer» D. Two cooling turbines and two heat exchangers | |
| 207. |
_The relative coefficient of performance is$? |
| A. | Actual COP/theoretical COP |
| B. | Theoretical COP/actual COP |
| C. | Actual COP √ó theoretical COP |
| D. | None of these |
| Answer» B. Theoretical COP/actual COP | |
| 208. |
_The relative humidity lines on a psychrometric chart are$? |
| A. | Vertical and uniformly spaced |
| B. | Horizontal and uniformly spaced |
| C. | Horizontal and non-uniformly spaced |
| D. | Curved lines |
| Answer» E. | |
| 209. |
_One tonne of refrigeration (1TR) means that the heat removing capacity is$? |
| A. | 21 kJ/min |
| B. | 210 kJ/min |
| C. | 420 kJ/min |
| D. | 620 kJ/min |
| Answer» C. 420 kJ/min | |
| 210. |
_Carbon dioxide is$? |
| A. | Colourless |
| B. | Odourless |
| C. | Non-flammable |
| D. | All of these |
| Answer» E. | |
| 211. |
_The curved lines on a psychrometric chart indicates$? |
| A. | Dry bulb temperature |
| B. | Wet bulb temperature |
| C. | Dew point temperature |
| D. | Relative humidity |
| Answer» E. | |
| 212. |
_An Electrolux refrigerator is called a _________ absorption system.$? |
| A. | Single fluid |
| B. | Two fluids |
| C. | Three fluids |
| D. | None of these |
| Answer» D. None of these | |
| 213. |
_Air refrigeration operates on$? |
| A. | Carnot cycle |
| B. | Reversed Carnot cycle |
| C. | Rankine’s cycle |
| D. | Brayton cycle |
| Answer» E. | |
| 214. |
_The human body feels comfortable when the heat stored in the body is$? |
| A. | Positive |
| B. | Negative |
| C. | Zero |
| D. | None of these |
| Answer» D. None of these | |
| 215. |
_In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be$? |
| A. | 0.3 |
| B. | 0.6 |
| C. | 0.67 |
| D. | 1.5 |
| Answer» C. 0.67 | |
| 216. |
_For air conditioning the operation theater in a hospital, the percentage of outside air in the air supplied is$? |
| A. | Zero |
| B. | 20 |
| C. | 50 |
| D. | 100 |
| Answer» E. | |
| 217. |
_The C.O.P. of a heat pump working on a reversed Carnot cycle is$? |
| A. | T‚ÇÅ/(T‚ÇÇ - T‚ÇÅ) |
| B. | (T‚ÇÇ - T‚ÇÅ)/T‚ÇÅ |
| C. | (T‚ÇÅ - T‚ÇÇ)/T‚ÇÅ |
| D. | T‚ÇÇ/(T‚ÇÇ - T‚ÇÅ) |
| Answer» E. | |
| 218. |
_The relative coefficient of performance is equal to$? |
| A. | (Theoretical C.O.P.)/ (Actual C.O.P.) |
| B. | (Actual C.O.P.) /(Theoretical C.O.P.) |
| C. | (Actual C.O.P.) √ó (Theoretical C.O.P.) |
| D. | None of these |
| Answer» C. (Actual C.O.P.) ‚àö√≥ (Theoretical C.O.P.) | |
| 219. |
_The relative humidity is defined as$? |
| A. | The mass of water vapour present in 1 m3 of dry air |
| B. | The mass of water vapour present in 1 kg of dry air |
| C. | The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure |
| D. | The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure |
| Answer» E. | |
| 220. |
_Degree of saturation or percentage humidity is$? |
| A. | The mass of water vapour present in 1 m³ of dry air |
| B. | The mass of water vapour present in 1 kg of dry air |
| C. | The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure |
| D. | The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure |
| Answer» D. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure | |
| 221. |
_Highest temperature encountered in refrigeration cycle should be$? |
| A. | Near critical temperature of refrigerant |
| B. | Above critical temperature |
| C. | At critical Temperature |
| D. | Much below critical temperature |
| Answer» E. | |
| 222. |
_The sub-cooling in a refrigeration cycle$? |
| A. | Does not alter C.O.P. |
| B. | Increases C.O.P. |
| C. | Decreases C.O.P. |
| D. | None of these |
| Answer» C. Decreases C.O.P. | |
| 223. |
_The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure, is called$? |
| A. | Humidity ratio |
| B. | Relative humidity |
| C. | Absolute humidity |
| D. | Degree of saturation |
| Answer» C. Absolute humidity | |
| 224. |
_In chemical dehumidification process,$? |
| A. | Dew point temperature decreases |
| B. | Wet bulb temperature decreases |
| C. | Dry bulb temperature increases |
| D. | All of these |
| Answer» E. | |
| 225. |
_The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity)$? |
| A. | 25°C DBT and 100% RH |
| B. | 20°C DBT and 80% RH |
| C. | 22°C DBT and 60% RH |
| D. | 25°C DBT and 40% RH |
| Answer» D. 25¬¨‚àûC DBT and 40% RH | |
| 226. |
_For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of$? |
| A. | Copper |
| B. | Aluminium |
| C. | Steel |
| D. | Brass |
| Answer» D. Brass | |
| 227. |
_Which of the following statement is wrong?$? |
| A. | The value of C.O.P. is always greater than one |
| B. | In a vapour compression system, the condition of refrigerant before entering the compressor is dry saturated vapour |
| C. | The space between the saturated liquid line and saturated vapour line, in a pressure enthalpy chart, is wet vapour region |
| D. | None of the above |
| Answer» E. | |
| 228. |
_In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to$? |
| A. | Collect liquid refrigerant and prevent it from going to compressor |
| B. | Detect liquid in vapour |
| C. | Superheat the vapour |
| D. | Collect vapours |
| Answer» B. Detect liquid in vapour | |
| 229. |
_During adiabatic saturation process on unsaturated air __________ remains constant.$? |
| A. | Relative humidity |
| B. | Dew point temperature |
| C. | Dry bulb temperature |
| D. | Wet bulb temperature |
| Answer» E. | |
| 230. |
_The refrigerant for a refrigerator should have$? |
| A. | High sensible heat |
| B. | High total heat |
| C. | High latent heat |
| D. | Low latent heat |
| Answer» D. Low latent heat | |
| 231. |
_Formation of frost on evaporator in refrigerator$? |
| A. | Results in loss of heat due to poor heat transfer |
| B. | Increases heat transfer rate |
| C. | Is immaterial |
| D. | Can be avoided by proper design |
| Answer» B. Increases heat transfer rate | |
| 232. |
_In vapour compression cycle, the condition of refrigerant is very wet vapour$? |
| 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 compressor |
| Answer» E. | |
| 233. |
_Mass flow ratio of NH‚ÇÉ in comparison to Freon-12 for same refrigeration load and same temperature limits is of the order of$? |
| A. | 1: 1 |
| B. | 1: 9 |
| C. | 9: 1 |
| D. | 1: 3 |
| Answer» C. 9: 1 | |
| 234. |
_The operating temperature of a cold storage is -2°C. The heat leakage from the surrounding is 30 kW for the ambient temperature of 40°C. The actual C.O.P. of refrigeration plant used is one fourth that of ideal plant working between the same temperatures. The power required to drive the plant is$? |
| A. | 1.86 kW |
| B. | 3.72 kW |
| C. | 7.44 kW |
| D. | 18.6 kW |
| Answer» E. | |
| 235. |
_A refrigeration system$? |
| A. | Removes heat from a low temperature body and delivers it to a high temperature body |
| B. | Removes heat from a high temperature body and delivers it to a low temperature body |
| C. | Rejects energy to a low temperature body |
| D. | None of the above |
| Answer» B. Removes heat from a high temperature body and delivers it to a low temperature body | |
| 236. |
The undesirable property of a refrigerant is$? |
| A. | Non-toxic |
| B. | Non-flammable |
| C. | Non-explosive |
| D. | High boiling point |
| Answer» E. | |
| 237. |
The dehumidification process, on the psychrometric chart, is shown by$? |
| A. | Horizontal line |
| B. | Vertical line |
| C. | Inclined line |
| D. | Curved line |
| Answer» C. Inclined line | |
| 238. |
The pressure at the inlet of a refrigerant compressor is called$? |
| A. | Suction pressure |
| B. | Discharge pressure |
| C. | Critical pressure |
| D. | Back pressure |
| Answer» B. Discharge pressure | |
| 239. |
A human body feels comfortable when the heat produced by the metabolism of human body is equal to the$? |
| A. | Heat dissipated to the surroundings |
| B. | Heat stored in the human body |
| C. | Sum of (A) and (B) |
| D. | Difference of (A) and (B) |
| Answer» D. Difference of (A) and (B) | |
| 240. |
Vertical lines on pressure-enthalpy chart show constant$? |
| A. | Pressure lines |
| B. | Temperature lines |
| C. | Total heat lines |
| D. | Entropy lines |
| Answer» D. Entropy lines | |
| 241. |
The coefficient of performance is the ratio of the refrigerant effect to the$? |
| A. | Heat of compression |
| B. | Work done by compressor |
| C. | Enthalpy increase in compressor |
| D. | All of the above |
| Answer» E. | |
| 242. |
When the air is passed through an insulated chamber having sprays of water maintained at a temperature higher than the dew point temperature of entering air but lower than its dry bulb temperature, then the air is said to be$? |
| A. | Cooled and humidified |
| B. | Cooled and dehumidified |
| C. | Heated and humidified |
| D. | Heated and dehumidified |
| Answer» B. Cooled and dehumidified | |
| 243. |
During humidification process, __________ increases.$? |
| A. | Wet bulb temperature |
| B. | Relative humidity |
| C. | Dry bulb temperature |
| D. | Specific humidity |
| Answer» C. Dry bulb temperature | |
| 244. |
Which of the following cycles uses air as the refrigerant?$? |
| A. | Ericson |
| B. | Stirling |
| C. | Carnot |
| D. | Bell Coleman |
| Answer» E. | |
| 245. |
In vapour compression cycle the condition off refrigerant is dry saturated vapour$? |
| A. | After passing through the condenser |
| B. | Before passing through the condenser |
| C. | After passing through the expansion or throttle valve |
| D. | Before entering the compressor |
| Answer» E. | |
| 246. |
Chaperon equation is a relation between$? |
| A. | Temperature, pressure and enthalpy |
| B. | Specific volume and enthalpy |
| C. | Temperature and enthalpy |
| D. | Temperature, pressure, specific volume and enthalpy |
| Answer» E. | |
| 247. |
The Freon group of refrigerants are$? |
| A. | Halocarbon refrigerants |
| B. | Zoetrope refrigerants |
| C. | Inorganic refrigerants |
| D. | Hydrocarbon refrigerants |
| Answer» B. Zoetrope refrigerants | |
| 248. |
The general rule for rating refrigeration systems (excepting for CO‚ÇÇ system) is to approximate following h.p. per ton of refrigeration$? |
| A. | 0.1 to 0.5 h.p. per ton of refrigeration |
| B. | 0.5 to 0.8 h.p. per ton of refrigeration |
| C. | 1 to 2 h.p. per ton of refrigeration |
| D. | 2 to 5 h.p. per ton of refrigeration |
| Answer» D. 2 to 5 h.p. per ton of refrigeration | |
| 249. |
The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is$? |
| A. | Bigger |
| B. | Smaller |
| C. | Equal |
| D. | Smaller/bigger depending on capacity |
| Answer» B. Smaller | |
| 250. |
In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be$? |
| A. | High, of the order of 25° |
| B. | As low as possible (3 to 11°C) |
| C. | Zero |
| D. | Any value |
| Answer» C. Zero | |