McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
Chapters
| 251. |
A water cooler is installed with one ton vapour compression cycle. In 24 hours it will provide |
| A. | 0.1 ton of cold water |
| B. | One tonne of cold water |
| C. | The change is gradual throughout the cycle |
| D. | More than one tonne of cold water |
| E. | Half ton of cold water |
| Answer» D. More than one tonne of cold water | |
| 252. |
In rainy season desert coolers become ineffective |
| A. | Because of low temperature |
| B. | Pleasant weather |
| C. | Rain serves the purpose of cooler |
| D. | Humidity of air increases |
| E. | None of the above |
| Answer» D. Humidity of air increases | |
| 253. |
When Freon 12 is the refrigerant, the condenser and evaporator cables are made of |
| A. | Aluminium |
| B. | Cast iron |
| C. | Steel |
| D. | Copper |
| E. | Wrought iron |
| Answer» D. Copper | |
| 254. |
In vapour absorption system using ammonia, water is required for |
| A. | Absorber only |
| B. | Separator only |
| C. | Condenser, absorber and separator |
| D. | Condenser only |
| E. | Condenser and absorber |
| Answer» C. Condenser, absorber and separator | |
| 255. |
The ratio of mass of water vapour associated with unit mass of dry air to the mass of water vapour associated with unit mass of dry air saturated at the same temperature is known as |
| A. | Relative humidity |
| B. | Specific humidity decreases |
| C. | Humidity ratio |
| D. | Degree of saturation |
| E. | None of the above |
| Answer» D. Degree of saturation | |
| 256. |
In a refrigerator system if compressor fails to operate, the probable reason could be |
| A. | Power failure |
| B. | Low voltage |
| C. | Burnt motor |
| D. | Fuse blown |
| E. | Any of the above |
| Answer» E. Any of the above | |
| 257. |
A thermometer in vapour compression system is installed in the main line close to the compressor |
| A. | As it helps the operator to adjust compressor for greatest efficiency |
| B. | As temperature indicates whether liquid or vapour refrigerant is going to compressor |
| C. | As temperature helps in calculating the coefficient of performance |
| D. | As the performance of other units of the cycle can be controlled |
| E. | None of the above |
| Answer» A. As it helps the operator to adjust compressor for greatest efficiency | |
| 258. |
White ice is |
| A. | Sub-cooled water |
| B. | Fast cooled water |
| C. | Due to dissolved air, gases and impurities |
| D. | Produced by blowing air during freezing |
| E. | None of the above |
| Answer» C. Due to dissolved air, gases and impurities | |
| 259. |
In which type of single phase motor the starting torque is low |
| A. | Capacitor start type |
| B. | Shaded pole type |
| C. | Starting torque is same in all motors |
| D. | Permanent split capacitor type |
| E. | Capacitor start and capacitor run type |
| Answer» B. Shaded pole type | |
| 260. |
Air conditioning means |
| A. | All above |
| B. | Removal of air impurities |
| C. | Heating |
| D. | Dehumidifying |
| E. | Cooling |
| Answer» A. All above | |
| 261. |
Dew points temperature is an indication of |
| A. | Moisture content of air |
| B. | Dryness of air |
| C. | Lowest temperature where air and water vapour start separating |
| D. | Condition air |
| E. | Any of the above |
| Answer» A. Moisture content of air | |
| 262. |
The most common type of vapour absorption system in use for industrial application is |
| A. | Hydrogen and water |
| B. | Freon 22 and water |
| C. | Brine and water |
| D. | Freon 12 and water |
| E. | Ammonia and water |
| Answer» E. Ammonia and water | |
| 263. |
Brazing is the process used for joining |
| A. | Two ferrous materials |
| B. | One ferrous and one non-ferrous material |
| C. | Two non-ferrous materials |
| D. | Two non-metals |
| E. | None of the above |
| Answer» C. Two non-ferrous materials | |
| 264. |
Of the following chemicals the liquid having the greatest cooling effect on an individual is |
| A. | Water |
| B. | Water containing ammonium hydroxide |
| C. | Ether |
| D. | Alcohol |
| E. | Brine |
| Answer» D. Alcohol | |
| 265. |
In vapour absorption system the function of rectifier is |
| A. | To cool the vapour leaving the analyzer |
| B. | To separate ammonia and water |
| C. | To dissolve ammonia in water |
| D. | To add energy from external source |
| E. | None of the above |
| Answer» A. To cool the vapour leaving the analyzer | |
| 266. |
Sometimes refrigeration plants use cooling towers. The water cooled in those towers is supplied |
| A. | For defrosting evaporator coils |
| B. | To cool compressor cylinder only |
| C. | To cool refrigerant in evaporator |
| D. | To cool refrigerant in condenser |
| E. | None of the above |
| Answer» D. To cool refrigerant in condenser | |
| 267. |
When moisture is added to air at constant dry bulb temperature, the process is known as |
| A. | Humidification |
| B. | Sensible cooling |
| C. | Wetting |
| D. | Chilling |
| E. | None of the above |
| Answer» A. Humidification | |
| 268. |
The condition of refrigerant before and after the condenser in a vapour compression cycle is |
| A. | Wet vapour, wet vapour |
| B. | Dry saturated, wet vapour |
| C. | Dry saturated, dry saturated |
| D. | Liquid, liquid |
| E. | Dry saturated, saturated liquid |
| Answer» E. Dry saturated, saturated liquid | |
| 269. |
The COP of a reversed Carnot cycle is 5. The ratio of highest absolute temperature to the lowest absolute temperature |
| A. | 0.8 |
| B. | 1.2 |
| C. | 0.2 |
| D. | 1.25 |
| E. | 5 |
| Answer» B. 1.2 | |
| 270. |
In case the relative humidity of atmospheric air is 100% the rate of evaporation of water will be |
| A. | Half the water already air |
| B. | Very high |
| C. | Zero |
| D. | Slow |
| E. | Half the water already air |
| Answer» C. Zero | |
| 271. |
In which of the following plants secondary refrigerant is used? |
| A. | Domestic refrigerator |
| B. | Room air conditioner |
| C. | Deep freezer |
| D. | Ice plant |
| E. | None of the above |
| Answer» D. Ice plant | |
| 272. |
If the suction pressure of a refrigeration compressor is too high, it shows |
| A. | Lack of refrigerant on cycle |
| B. | Excessive load and evaporator |
| C. | Negligible load on evaporator |
| D. | Any of above |
| E. | None of the above |
| Answer» B. Excessive load and evaporator | |
| 273. |
The crankcase explosion of a refrigeration compressor |
| A. | Occurs due to ignition of vapours in compressor crank case |
| B. | Occurs when load is too high |
| C. | Means breakdown in compression |
| D. | Occurs between piston and cylinder heads |
| E. | Means ignition of refrigeration due to high temperature |
| Answer» A. Occurs due to ignition of vapours in compressor crank case | |
| 274. |
A cooling tower cools water |
| A. | Below wet bulb temperature |
| B. | Equal to wet bulb temperature |
| C. | Slightly above wet bulb temperature |
| D. | Wet bulb has no bearing on cooling load performance |
| E. | None of the above |
| Answer» C. Slightly above wet bulb temperature | |
| 275. |
While designing air conditioning system for a theatre the various heat loads are categorized as given below. Which one will give lowest heat load? |
| A. | Lights |
| B. | Neither absorbs nor discards heat |
| C. | Outside temperature in summer |
| D. | Human beings |
| E. | Direct sun |
| Answer» A. Lights | |
| 276. |
The secondary refrigerant used in milk chilling plants is usually |
| A. | Brine |
| B. | Ammonia solution |
| C. | Glycol |
| D. | Sodium silicate |
| E. | Any of the above |
| Answer» C. Glycol | |
| 277. |
Hydrogen cannot be liquefied at room temperature by the application of pressure, because |
| A. | It is a diatomic molecule |
| B. | It has high viscosity |
| C. | Its critical temperature is lower than the normal room temperature |
| D. | Its thermal conductivity is high |
| E. | It has low density |
| Answer» C. Its critical temperature is lower than the normal room temperature | |
| 278. |
The condension of moisture contained in air will take place at |
| A. | Any where between dry bulb temperature and wet bulb temperature |
| B. | Dew point temperature |
| C. | Dry bulb temperature |
| D. | Wet bulb temperature |
| E. | Saturation temperature |
| Answer» B. Dew point temperature | |
| 279. |
If a discharge pressure of a refrigeration compressor is too high, it shows there is (are) |
| A. | Too little or too warm condenser water |
| B. | Fouled tubes in shell and tube condenser |
| C. | Improper operations of evaporator condenser |
| D. | Overcharge of refrigerant |
| E. | Any of the above |
| Answer» E. Any of the above | |
| 280. |
The statement that molecular weight of all gases occupy the same volume at NTP is known as |
| A. | First law of thermodynamics |
| B. | Joules law |
| C. | Charle's law |
| D. | Avogadro's law |
| E. | Dalton's law |
| Answer» D. Avogadro's law | |
| 281. |
The condition of refrigerant before and after the expansion or throttle valve in a vapour compression system is |
| A. | Wet vapour, very wet vapour |
| B. | Wet vapour, dry vapour |
| C. | High pressure saturated liquid, very wet vapour |
| D. | Very wet vapour, high pressure, saturated liquid |
| E. | None of the above |
| Answer» C. High pressure saturated liquid, very wet vapour | |
| 282. |
The function of desuperheating coil in a condenser is |
| A. | To remove heat from condenser |
| B. | To improve performance of a condenser |
| C. | To discharge the heat exchanged in condenser to the surroundings |
| D. | To remove the heat of superheat of the refrigerant before it enters the condenser |
| E. | None of the above |
| Answer» D. To remove the heat of superheat of the refrigerant before it enters the condenser | |
| 283. |
When the air temperature reaches the point where relative humidity is 100% the air is saturated because it cannot hold any more moisture. This temperature is called |
| A. | Freezing point |
| B. | Partial freezing point |
| C. | Dew point of air |
| D. | Dew point |
| E. | Dew point of water vapour |
| Answer» D. Dew point | |
| 284. |
An increase in the movement of the molecules within a solid, liquid or gas corresponds to |
| A. | A drop in temperature |
| B. | No change in temperature |
| C. | Latent heat addition/removal |
| D. | A rise in temperature |
| E. | None of the above |
| Answer» D. A rise in temperature | |
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