MCQOPTIONS
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MCQOPTIONS
This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The absolute humidity is the mass of water vapour present in 1 m3 of dry air. |
| A. | Agree |
| B. | Disagree |
| Answer» B. Disagree | |
| 2. |
During heating and dehumidification process, dry bulb temperature |
| A. | remains constant |
| B. | increases |
| C. | decreases |
| Answer» C. decreases | |
| 3. |
A refrigerant compressor is used to |
| A. | raise the pressure of the refrigerant |
| B. | raise the temperature of the refrigerant |
| C. | circulate the refrigerant through the refrigerating system |
| D. | all of the above |
| Answer» E. | |
| 4. |
In which of the following refrigeration system, waste heat can be effectively used? |
| A. | Vapour compression cycle |
| B. | Vapour absorption cycle |
| C. | Air refrigeration cycle |
| D. | none of these |
| Answer» C. Air refrigeration cycle | |
| 5. |
The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T1 = Lowest absolute temperature, and T2 = Highest absolute temperature) |
| A. | <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/415-144-1.png"> |
| B. | <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/415-144-2.png"> |
| C. | <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/415-144-3.png"> |
| D. | <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/415-144-4.png"> |
| Answer» B. <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/415-144-2.png"> | |
| 6. |
The process of heat transfer from one particle of the body to another by the actual motion of the heated particles, is called |
| A. | conduction |
| B. | convection |
| C. | radiation |
| Answer» C. radiation | |
| 7. |
The wave length of the radiation emitted depends only on the temperature and is independent of the material of the body. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8. |
A steam pipe is to be lined with two layers of insulating materials of different thermal conductivities. For the minimum heat transfer, |
| A. | the better insulation must be put inside |
| B. | the better insulation must be put outside |
| C. | one could place either insulation on either side |
| D. | one should take into account the steam temperature before deciding as to which insulation is put where |
| Answer» B. the better insulation must be put outside | |
| 9. |
In a parallel flow heat exchanger, the rate of flow of heat and the rate of decrease of temperature are maximum. |
| A. | Yes |
| B. | No |
| Answer» B. No | |
| 10. |
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 | |
| 11. |
The refrigerant used in small-tonnage commercial machines (hermetically sealed units) is |
| A. | ammonia |
| B. | carbon dioxide |
| C. | sulphur dioxide |
| D. | R-12 |
| Answer» D. R-12 | |
| 12. |
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 | |
| 13. |
The thermostatic expansion valve is also called |
| A. | constant pressure valve |
| B. | constant temperature valve |
| C. | constant superheat valve |
| D. | none of these |
| Answer» D. none of these | |
| 14. |
In figure shown, E is a heat engine with efficiency of 0.4 and R is a refrigerator. It is given that Q2 + Q4 = 3Q1. The C.O.P. of the refrigerator is |
| A. | 2.5 |
| B. | 3.0 |
| C. | 4.0 |
| D. | 5.0 |
| Answer» E. | |
| 15. |
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) | |
| 16. |
During sensible cooling, |
| A. | relative humidity remains constant |
| B. | wet bulb temperature increases |
| C. | specific humidity increases |
| D. | partial pressure of vapour remains constant |
| Answer» E. | |
| 17. |
Cast iron during machining produces |
| A. | continuous chips |
| B. | discontinuous chips |
| C. | continuous chips with built-up-edge |
| D. | none of these |
| Answer» C. continuous chips with built-up-edge | |
| 18. |
The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as |
| A. | conduction |
| B. | free convection |
| C. | forced convection |
| D. | radiation |
| Answer» C. forced convection | |
| 19. |
Crater wear occurs mainly on the |
| A. | nose part, front relief face and side relief face of the cutting tool |
| B. | face of the cutting tool at a short distance from the cutting edge only |
| C. | cutting edge only |
| D. | front face only |
| Answer» C. cutting edge only | |
| 20. |
When the backgear is engaged in a backgeared headstock, the spindle speed reduces considerably. |
| A. | Agree |
| B. | Disagree |
| Answer» B. Disagree | |
| 21. |
The angle on which the strength of the tool depends is |
| A. | rake angle |
| B. | cutting angle |
| C. | clearance angle |
| D. | lip angle |
| Answer» B. cutting angle | |
| 22. |
In oblique cutting system, the maximum chip thickness |
| A. | occurs at the middle |
| B. | may not occur at the middle |
| C. | depends upon the material of the tool |
| D. | depends upon the geometry of the tool |
| Answer» C. depends upon the material of the tool | |
| 23. |
The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called |
| A. | First law of thermodynamics |
| B. | Newton's law of cooling |
| C. | Newton's law of heating |
| D. | Stefan's law |
| Answer» C. Newton's law of heating | |
| 24. |
The leakage in a refrigeration system using ammonia is detected by |
| A. | halide torch |
| B. | sulphur sticks |
| C. | soap and water |
| D. | all of these |
| Answer» C. soap and water | |
| 25. |
In a single point turning operation with a cemented carbide and steel combination having a Taylor exponent of 0.25, if the cutting speed is halved, then tool life will become |
| A. | half |
| B. | two times |
| C. | eight times |
| D. | sixteen times |
| Answer» E. | |
| 26. |
Which of the following operations can be performed with milling cutters? |
| A. | cutting key ways on shafts |
| B. | cutting external screw threads |
| C. | cutting teeth of spur gears |
| D. | all of these |
| Answer» E. | |
| 27. |
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 | |
| 28. |
The process, generally used in summer air conditioning to cool and dehumidify the air, is called |
| A. | humidification |
| B. | dehumidification |
| C. | heating and humidification |
| D. | cooling and dehumidification |
| Answer» E. | |
| 29. |
A simple air cooling system is good for __________ flight speeds. |
| A. | low |
| B. | high |
| Answer» B. high | |
| 30. |
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 | |
| 31. |
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 | |
| 32. |
R-12 is generally preferred over R-22 in deep freezers since |
| A. | it has low operating pressures |
| B. | it gives higher coefficient of performance |
| C. | it is miscible with oil over large range of temperatures |
| D. | all of the above |
| Answer» D. all of the above | |
| 33. |
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 | |
| 34. |
Sensible heat factor is given by (where S.H. = Sensible heat, and L.H. = Latent heat) |
| A. | <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/434-367-1.png"> |
| B. | <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/434-367-2.png"> |
| C. | <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/434-367-3.png"> |
| D. | <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/434-367-4.png"> |
| Answer» B. <img src="/_files/images/mechanical-engineering/heat-transfer-refrigeration-and-air-conditioning/434-367-2.png"> | |
| 35. |
During sub-cooling, sensible heat from a liquid refrigerant is removed. |
| A. | Yes |
| B. | No |
| Answer» B. No | |
| 36. |
The expression is used for calculating relative humidity. |
| A. | Yes |
| B. | No |
| Answer» C. | |
| 37. |
Stefan-Boltzmann law is applicable for heat transfer by convection. |
| A. | Agree |
| B. | Disagree |
| Answer» C. | |
| 38. |
The most commonly used method for the design of duct size is the |
| A. | velocity reduction method |
| B. | equal friction method |
| C. | static regain method |
| D. | dual or double method |
| Answer» D. dual or double method | |
| 39. |
The lowest temperature during the cycle in a vapour compression system occurs after |
| A. | compression |
| B. | expansion |
| C. | condensation |
| D. | evaporation |
| Answer» E. | |
| 40. |
During sensible cooling of air, specific humidity |
| A. | remains constant |
| B. | increases |
| C. | decreases |
| Answer» B. increases | |
| 41. |
The transfer of heat by molecular collision is known as |
| A. | conduction |
| B. | convection |
| C. | radiation |
| D. | none of these |
| Answer» B. convection | |
| 42. |
The transfer of heat by molecular collision is smallest in |
| A. | solids |
| B. | liquids |
| C. | gases |
| D. | none of these |
| Answer» D. none of these | |
| 43. |
The critical temperature is the temperature |
| A. | below which a gas does not obey gas laws |
| B. | above which a gas may explode |
| C. | below which a gas is always liquified |
| D. | above which a gas will never liquified |
| Answer» E. | |
| 44. |
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 | |
| 45. |
The evaporator changes the low pressure liquid refrigerant from the expansion valve into |
| A. | high pressure liquid refrigerant |
| B. | low pressure liquid and vapour refrigerant |
| C. | low pressure vapour refrigerant |
| D. | none of these |
| Answer» D. none of these | |
| 46. |
The mass of water vapour present in 1 kg of dry air, is called humidity ratio. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 47. |
The wet bulb depression indicates __________ humidity of the air. |
| A. | absolute |
| B. | relative |
| C. | specific |
| Answer» C. specific | |
| 48. |
The cooling system used for supersonic aircrafts and rockets is |
| A. | simple air cooling system |
| B. | boot-strap air cooling system |
| C. | reduced ambient air cooling system |
| D. | regenerative air cooling system |
| Answer» E. | |
| 49. |
The refrigerant widely used in domestic refrigerators is |
| A. | ammonia |
| B. | carbon dioxide |
| C. | sulphur dioxide |
| D. | R-12 |
| Answer» E. | |
| 50. |
When absorptivity ( ) = 1, reflectivity ( ) = 0 and transmittivity ( ) = 0, then the body is said to be a |
| A. | black body |
| B. | grey body |
| C. | opaque body |
| D. | white body |
| Answer» B. grey body | |