MCQOPTIONS
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MCQOPTIONS
This section includes 346 Mcqs, each offering curated multiple-choice questions to sharpen your GATE (Mechanical Engineering) knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
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. | |
| 152. |
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. | |
| 153. |
The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will |
| A. | Increase |
| B. | Decrease |
| C. | May increase or decrease depending on the type of refrigerant used |
| D. | Remain unaffected |
| Answer» B. Decrease | |
| 154. |
For obtaining high COP, the pressure range of compressor should be |
| A. | High |
| B. | Low |
| C. | Optimum |
| D. | Any value |
| Answer» C. Optimum | |
| 155. |
The pressure at the outlet of a refrigerant compressor is called |
| A. | Suction pressure |
| B. | Discharge pressure |
| C. | Critical pressure |
| D. | Back pressure |
| Answer» C. Critical pressure | |
| 156. |
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 | |
| 157. |
In a saturated air-water vapour mixture, the |
| A. | Dry bulb temperature is higher than wet bulb temperature |
| B. | Dew point temperature is lower than wet bulb temperature |
| C. | Dry bulb, wet bulb and dew point temperature are same |
| D. | Dry bulb temperature is higher than dew point temperature |
| Answer» D. Dry bulb temperature is higher than dew point temperature | |
| 158. |
The conditioned air supplied to the room must have the capacity to take up |
| A. | Room sensible heat load only |
| B. | Room latent heat load only |
| C. | Both room sensible heat and latent heat loads |
| D. | None of the above |
| Answer» D. None of the above | |
| 159. |
The difference between dry bulb temperature and dew point temperature, is called |
| A. | Dry bulb depression |
| B. | Wet bulb depression |
| C. | Dew point depression |
| D. | Degree of saturation |
| Answer» D. Degree of saturation | |
| 160. |
The difference between dry bulb temperature and wet bulb temperature, is called |
| A. | Dry bulb depression |
| B. | Wet bulb depression |
| C. | Dew point depression |
| D. | Degree of saturation |
| Answer» C. Dew point depression | |
| 161. |
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 | |
| 162. |
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. | |
| 163. |
It is desired to condition the outside air from 70% relative humidity and 45° C dry bulb temperature to 50% relative humidity and 25° C dry bulb temperature (room condition). The practical arrangement will be |
| A. | Dehumidification |
| B. | Cooling and humidification |
| C. | Cooling and dehumidification |
| D. | Dehumidification and pure sensible cooling |
| Answer» D. Dehumidification and pure sensible cooling | |
| 164. |
Chaperon equation is applicable for registration at |
| A. | Saturation point of vapour |
| B. | Saturation point of liquid |
| C. | Sublimation temperature |
| D. | Triple point |
| Answer» B. Saturation point of liquid | |
| 165. |
The coefficient of performance of Electrolux refrigerator is the ratio of |
| A. | Heat supplied by the gas burner to the heat absorbed by the evaporator |
| B. | Heat absorbed by the evaporator to the heat supplied by the gas burner |
| C. | Heat supplied by the gas burner minus the heat absorbed by the evaporator to the heat supplied by the gas burner |
| D. | Heat absorbed by the evaporator minus the heat supplied by the gas burner to the heat absorbed by the evaporator |
| Answer» C. Heat supplied by the gas burner minus the heat absorbed by the evaporator to the heat supplied by the gas burner | |
| 166. |
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 | |
| 167. |
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. | |
| 168. |
The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called |
| A. | Sub-cooling or under-cooling |
| B. | Super-cooling |
| C. | Normal cooling |
| D. | None of these |
| Answer» B. Super-cooling | |
| 169. |
Absorption system normally uses the following refrigerant |
| A. | Freon-11 |
| B. | Freon-22 |
| C. | CO2 |
| D. | Ammonia |
| Answer» E. | |
| 170. |
Refrigeration in aeroplanes usually employs the following refrigerant |
| A. | CO2 |
| B. | Freon-11 |
| C. | Freon-22 |
| D. | Air |
| Answer» E. | |
| 171. |
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 | |
| 172. |
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 | |
| 173. |
Most thermostatic expansion valves are set for a superheat of |
| A. | 5°C |
| B. | 10°C |
| C. | 15°C |
| D. | 20°C |
| Answer» B. 10°C | |
| 174. |
The bypass factor for a cooling coil |
| A. | Increases with increase in velocity of air passing through it |
| B. | Decreases with increase in velocity of air passing through it |
| C. | Remains unchanged with increase in velocity of air passing through it |
| D. | May increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering |
| Answer» B. Decreases with increase in velocity of air passing through it | |
| 175. |
A bootstrap air cooling system has |
| A. | One heat exchanger |
| B. | Two heat exchangers |
| C. | Three heat exchangers |
| D. | Four heat exchangers |
| Answer» C. Three heat exchangers | |
| 176. |
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 | |
| 177. |
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 | |
| 178. |
Air conditioning means |
| A. | Cooling |
| B. | Heating |
| C. | Dehumidifying |
| D. | All of these |
| Answer» E. | |
| 179. |
The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases, |
| A. | Will be higher |
| B. | Will be lower |
| C. | Will remain unaffected |
| D. | May be higher or lower depending upon the nature of non-condensable gases |
| Answer» B. Will be lower | |
| 180. |
In order to collect liquid refrigerant and to prevent it from going to a ________, a device known as accumulator is used at the suction of compressor. |
| A. | Compressor |
| B. | Condenser |
| C. | Expansion valve |
| D. | Evaporator |
| Answer» B. Condenser | |
| 181. |
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 | |
| 182. |
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 | |
| 183. |
One ton refrigeration corresponds to |
| A. | 50 kcal/ min |
| B. | 50 kcal/ hr |
| C. | 80 kcal/ min |
| D. | 80 kcal/ hr |
| Answer» B. 50 kcal/ hr | |
| 184. |
In a refrigeration system, heat absorbed in comparison to heat rejected is |
| A. | More |
| B. | Less |
| C. | Same |
| D. | More for small capacity and less for high capacity |
| Answer» C. Same | |
| 185. |
In a vapour compression refrigeration system, a throttle valve is used in place of an expander because |
| A. | It considerably reduces mass of the system |
| B. | It improves the C.O.P., as the condenser is small |
| C. | The positive work in isentropic expansion of liquid is very small |
| D. | It leads to significant cost reduction |
| Answer» D. It leads to significant cost reduction | |
| 186. |
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 | |
| 187. |
The specific humidity during cooling and dehumidification |
| A. | Remains constant |
| B. | Increases |
| C. | Decreases |
| D. | None of these |
| Answer» D. None of these | |
| 188. |
The value of C.O.P in vapour compression cycle is usually |
| A. | Always less than unity |
| B. | Always more than unity |
| C. | Equal to unity |
| D. | Any one of the above |
| Answer» C. Equal to unity | |
| 189. |
The refrigerant supplied to a compressor must be |
| A. | Superheated vapour refrigerant |
| B. | Dry saturated liquid refrigerant |
| C. | A mixture of liquid and vapour refrigerant |
| D. | None of these |
| Answer» B. Dry saturated liquid refrigerant | |
| 190. |
Where does the lowest temperature occur in a vapour compression cycle? |
| A. | Condenser |
| B. | Evaporator |
| C. | Compressor |
| D. | Expansion valve |
| Answer» C. Compressor | |
| 191. |
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. | |
| 192. |
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 | |
| 193. |
In Electrolux refrigerator |
| A. | Ammonia is absorbed in hydrogen |
| B. | Ammonia is absorbed in water |
| C. | Ammonia evaporates in hydrogen |
| D. | Hydrogen evaporates in ammonia |
| Answer» D. Hydrogen evaporates in ammonia | |
| 194. |
Bell Coleman cycle is a |
| A. | Reversed Carnot cycle |
| B. | Reversed Otto cycle |
| C. | Reversed Joule cycle |
| D. | Reversed Rankine cycle |
| Answer» D. Reversed Rankine cycle | |
| 195. |
The wet bulb temperature at 100% relative humidity is ________ dew point temperature. |
| A. | Same as |
| B. | Lower than |
| C. | Higher than |
| D. | None of these |
| Answer» B. Lower than | |
| 196. |
The relative coefficient of performance is |
| A. | Actual COP/theoretical COP |
| B. | Theoretical COP/actual COP |
| C. | Actual COP × theoretical COP |
| D. | None of these |
| Answer» B. Theoretical COP/actual COP | |
| 197. |
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 | |
| 198. |
One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice |
| A. | In 1 hour |
| B. | In 1 minute |
| C. | In 24 hours |
| D. | In 12 hours |
| Answer» D. In 12 hours | |
| 199. |
A mixture of dry air and water vapour, when the air has diffused the maximum amount of water vapour into it, is called |
| A. | Dry air |
| B. | Moist air |
| C. | Saturated air |
| D. | Specific humidity |
| Answer» D. Specific humidity | |
| 200. |
The superheated vapour region, in a pressure enthalpy chart, is represented by the space |
| A. | To the left of saturated liquid line |
| B. | To the right of saturated liquid line |
| C. | Between the saturated liquid line and saturated vapour line |
| D. | None of the above |
| Answer» D. None of the above | |