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MCQOPTIONS
This section includes 387 Mcqs, each offering curated multiple-choice questions to sharpen your Automobile Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
The C.O.P. of a heat pump working on a reversed Carnot cycle is |
| A. | T₁/(T₂ - T₁) |
| B. | (T₂ - T₁)/T₁ |
| C. | (T₁ - T₂)/T₁ |
| D. | T₂/(T₂ - T₁) |
| Answer» E. | |
| 52. |
In mechanical refrigeration system, the refrigerant has the maximum temperature |
| A. | in evaporator |
| B. | before expansion valve |
| C. | between compressor and condenser |
| D. | between condenser and evaporator |
| Answer» D. between condenser and evaporator | |
| 53. |
In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is |
| A. | high pressure saturated liquid |
| B. | wet vapour |
| C. | very wet vapour |
| D. | dry vapour |
| Answer» B. wet vapour | |
| 54. |
The ratio of the energy absorbed by the body to the total energy falling on it, is called |
| A. | absorptive power |
| B. | emissive power |
| C. | emissivity |
| D. | none of these |
| Answer» B. emissive power | |
| 55. |
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 | |
| 56. |
The by-pass factor, in case of sensible cooling of air, is given by (where td1 = Dry bulb temperature of air entering the cooling coil, td2 = Dry bulb temperature of air leaving the cooling coil, and td3 = Dry bulb temperature of the cooling coil) |
| A. | (td₁ -td₃)/( td₂ -td₃) |
| B. | (td₂ -td₃)/( td₁ -td₃) |
| C. | (td₃ -td₁)/( td₂ -td₃) |
| D. | (td₃ -td₂)/( td₁ -td₃) |
| Answer» C. (td₃ -td₁)/( td₂ -td₃) | |
| 57. |
The by-pass 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 | |
| 58. |
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 | |
| 59. |
A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100° C and leaves at 60° C. A cold fluid enters the heat exchanger at 40° C. The mean temperature difference between the two fluids is |
| A. | 20°C |
| B. | 40°C |
| C. | 60°C |
| D. | 66.7°C |
| Answer» B. 40°C | |
| 60. |
The temperature of air recorded by a thermometer, when the moisture present in it begins to condense, is called wet bulb temperature. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 61. |
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 | |
| 62. |
Fouling factor is used |
| A. | in heat exchanger design as a safety factor |
| B. | in case of Newtonian fluids |
| C. | when a liquid exchanges heat with a gas |
| D. | none of the above |
| Answer» B. in case of Newtonian fluids | |
| 63. |
Carbon dioxide is |
| A. | colourless |
| B. | odourless |
| C. | non-flammable |
| D. | all of these |
| Answer» E. | |
| 64. |
The operating pressure for refrigerating units using R-12 as a refrigerant is |
| A. | 2 bar |
| B. | 8 bar |
| C. | 15 bar |
| D. | 30 bar |
| Answer» C. 15 bar | |
| 65. |
The refrigerant widely used in domestic refrigerators is |
| A. | ammonia |
| B. | carbon dioxide |
| C. | sulphur dioxide |
| D. | R-12 |
| Answer» E. | |
| 66. |
Dry bulb temperature is the temperature of air recorded by a thermometer, when |
| A. | it is not affected by the moisture present in the air |
| B. | its bulb is surrounded by a wet cloth exposed to the air |
| C. | the moisture present in it begins to condense |
| D. | none of the above |
| Answer» B. its bulb is surrounded by a wet cloth exposed to the air | |
| 67. |
For a given dry bulb temperature, as the relative humidity __________ the wet bulb temperature will increase. |
| A. | increases |
| B. | decreases |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 68. |
The humidification process, on the psychrometric chart is shown by |
| A. | horizontal line |
| B. | vertical line |
| C. | inclined line |
| D. | curved line |
| Answer» C. inclined line | |
| 69. |
In counter-current flow heat exchangers |
| A. | both the fluids at inlet are in their hottest state |
| B. | both the fluids at inlet are in their coldest state |
| C. | both the fluids at exit are in their hottest state |
| D. | one fluid is coldest and the other is hottest at inlet |
| Answer» B. both the fluids at inlet are in their coldest state | |
| 70. |
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 | |
| 71. |
An evaporator is also known as |
| A. | freezing coil |
| B. | cooling coil |
| C. | chilling coil |
| D. | all of these |
| Answer» E. | |
| 72. |
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 | |
| 73. |
Wein's law states that the wave length corresponding to __________ is proportional to the absolute temperature. |
| A. | minimum energy |
| B. | maximum energy |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 74. |
The wet bulb temperature during sensible cooling of air |
| A. | remains constant |
| B. | increases |
| C. | decreases |
| D. | None of these |
| Answer» D. None of these | |
| 75. |
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 | |
| 76. |
Most air cooled condensers are designed to operate with a temperature difference of |
| A. | 5°C |
| B. | 8°C |
| C. | 14°C |
| D. | 22°C |
| Answer» D. 22°C | |
| 77. |
The heat is transferred by conduction, convection and radiation in |
| A. | melting of ice |
| B. | boiler furnaces |
| C. | condensation of steam in condenser |
| D. | none of these |
| Answer» C. condensation of steam in condenser | |
| 78. |
The inclined and non-uniformly spaced straight lines on a psychrometric chart indicates wet bulb temperature. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 79. |
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. | |
| 80. |
In a shell and tube heat exchanger, baffles are provided on the shell side to |
| A. | improve heat transfer |
| B. | provide support for tubes |
| C. | prevent stagnation of shell side fluid |
| D. | all of these |
| Answer» E. | |
| 81. |
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. | |
| 82. |
Which of the following refrigerant has the lowest boiling point? |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | R-12 |
| Answer» C. Sulphur dioxide | |
| 83. |
The index which corelates the combined effects of air temperature, relative humidity and air velocity on the human body, is known as |
| A. | mean radiant temperature |
| B. | effective temperature |
| C. | dew point temperature |
| D. | none of these |
| Answer» C. dew point temperature | |
| 84. |
If the condenser temperature is kept constant, the coefficient of performance of a refrigeration cycle increases with the increase in evaporator temperature. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 85. |
In case of liquids and gases, the heat transfer takes place according to |
| A. | conduction |
| B. | convection |
| C. | radiation |
| D. | none of these |
| Answer» C. radiation | |
| 86. |
The expression Q = ρ AT4 is called |
| A. | Fourier equation |
| B. | Stefan-Boltzmann equation |
| C. | Newton-Rikhmann equation |
| D. | Joseph-Stefan equation |
| Answer» C. Newton-Rikhmann equation | |
| 87. |
The temperature below which a gas is always liquified, is known as critical temperature. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 88. |
Fourier's law of heat conduction gives the heat flow for |
| A. | irregular surfaces |
| B. | non-uniform temperature surfaces |
| C. | one dimensional cases only |
| D. | two dimensional cases only |
| Answer» D. two dimensional cases only | |
| 89. |
The material of pipe lines for a system using freon as a refrigerant should be |
| A. | brass |
| B. | copper |
| C. | steel |
| D. | aluminium |
| Answer» C. steel | |
| 90. |
The wet bulb depression is zero when relative humidity is |
| A. | zero |
| B. | 0.5 |
| C. | 0.75 |
| D. | 1.0 |
| Answer» E. | |
| 91. |
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 | |
| 92. |
The fluids used in electrolux refrigerator are |
| A. | water and hydrogen |
| B. | ammonia and hydrogen |
| C. | ammonia, water and hydrogen |
| D. | none of these |
| Answer» D. none of these | |
| 93. |
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 | |
| 94. |
A pressure gauge on the discharge side of a refrigerant compressor reads too high. The reasons will be |
| A. | lack of cooling water |
| B. | water temperature being high |
| C. | dirty condenser surface |
| D. | all of these |
| Answer» E. | |
| 95. |
The condition of refrigerant after passing through the condenser in a vapour compression system is |
| A. | saturated liquid |
| B. | wet vapour |
| C. | dry saturated vapour |
| D. | superheated vapour |
| Answer» B. wet vapour | |
| 96. |
A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as |
| A. | A.Cmin/U |
| B. | U/A.Cmin |
| C. | A.U.Cmin |
| D. | A.U/Cmin |
| Answer» E. | |
| 97. |
The condition of refrigerant as it leaves the compressor in a vapour compression system is |
| A. | saturated liquid |
| B. | wet vapour |
| C. | dry saturated vapour |
| D. | superheated vapour |
| Answer» E. | |
| 98. |
The critical pressure of a liquid is the pressure |
| A. | above which a liquid will remain a liquid |
| B. | above which a liquid will explode |
| C. | above which a liquid will always convert into a vapour |
| D. | below which a liquid will always be in vapour form |
| Answer» B. above which a liquid will explode | |
| 99. |
In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in |
| A. | parallel flow |
| B. | counter flow |
| C. | cross flow |
| D. | all of these |
| Answer» E. | |
| 100. |
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 | |