McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
Chapters
| 51. |
Dissociation can be considered as |
| A. | disintegration of combustion products at high temperature |
| B. | reverse process of combustion |
| C. | heat absorption process |
| D. | all of the above |
| Answer» D. all of the above | |
| 52. |
Time loss factor in actual cycle is due to |
| A. | Progressive combustion |
| B. | heat loss through cylinder walls |
| C. | gas leakage |
| D. | friction |
| Answer» A. Progressive combustion | |
| 53. |
The major loss in a SI engine is due to |
| A. | exhaust blow down |
| B. | pumping |
| C. | incomplete combustion |
| D. | variation in specific heat and chemical equilibrium |
| Answer» D. variation in specific heat and chemical equilibrium | |
| 54. |
Fuel-air cycle efficiency is less than air-standard cycle efficiency by an amount equal to |
| A. | pumping loss |
| B. | friction loss |
| C. | loss due to specific heat variation and chemical equilibrium |
| D. | exhaust blow down loss |
| Answer» C. loss due to specific heat variation and chemical equilibrium | |
| 55. |
The major loss in a CI engine is |
| A. | direct heat loss |
| B. | loss due to incomplete combustion |
| C. | rubbing friction loss |
| D. | pumping loss |
| Answer» B. loss due to incomplete combustion | |
| 56. |
The ratio of the actual efficiency and the fuel-air cycle efficiency for CI engines is about |
| A. | 0.2-0.3 |
| B. | 0.5-0.6 |
| C. | 1.0 |
| D. | 0.6-0.8 |
| Answer» D. 0.6-0.8 | |
| 57. |
In an actual SI engine the pumping loss with respect to speed |
| A. | decreases |
| B. | Increases |
| C. | remains constant |
| D. | nothing to do with speed |
| Answer» B. Increases | |
| 58. |
The volumetric efficiency is affected by |
| A. | the exhaust gas in the clearance volume |
| B. | the design of intake and exhaust valve |
| C. | valve timing |
| D. | all of the above |
| Answer» D. all of the above | |
| 59. |
The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is |
| A. | same |
| B. | less |
| C. | more |
| D. | more or less depending on power rating |
| Answer» C. more | |
| 60. |
In a typical medium speed, 4-stroke cycle diesel engine |
| A. | fuel injection starts at 10° before to dead center and ends at 20° after tor dead center |
| B. | fuel injection starts at top dead center and ends at 20° after top dead center |
| C. | fuel injection starts at just before top dead center and ends just after top dead center |
| D. | may start and end anywhere |
| Answer» A. fuel injection starts at 10° before to dead center and ends at 20° after tor dead center | |
| 61. |
The amount of heat liberated by complete combustion of unit quantity of fuel is known as ________ |
| A. | Agitation |
| B. | Combustion |
| C. | Calorific value |
| D. | Thermogenesis |
| Answer» C. Calorific value | |
| 62. |
The calorific value of gaseous fuels is expressed in terms of |
| A. | kcal |
| B. | B. kcal/kg |
| C. | C. kcal/m² |
| D. | D. kcal/m3 |
| Answer» D. D. kcal/m3 | |
| 63. |
What is the significance of calorific value? |
| A. | Helps in deciding which fuel is good |
| B. | Helps in locating fuel |
| C. | Helps in deciding ignition temperature |
| D. | Helps in deciding fire point |
| Answer» A. Helps in deciding which fuel is good | |
| 64. |
Which gas has the highest calorific value among given option? |
| A. | Oxygen |
| B. | Helium |
| C. | Hydrogen |
| D. | Nitrogen |
| Answer» C. Hydrogen | |
| 65. |
Which calorimeter is used to find calorific values of solid and liquid fuels? |
| A. | Boy’s calorimeter |
| B. | Bomb calorimeter |
| C. | Junker’s calorimeter |
| D. | Calvet-type calorimeter |
| Answer» B. Bomb calorimeter | |
| 66. |
Which calorimeter is used to find calorific values of gaseous fuels? |
| A. | Bomb calorimeter |
| B. | Junker calorimeter |
| C. | Adiabatic calorimeter |
| D. | Isothermal titration calorimeter |
| Answer» B. Junker calorimeter | |
| 67. |
What is the factor on which, difference between the two heating values of fuel depends on? |
| A. | Physical properties |
| B. | Reactants |
| C. | Chemical composition |
| D. | Products |
| Answer» C. Chemical composition | |
| 68. |
The Bomb calorimeter is used to determine the calorific value of: |
| A. | solids and liquid fuels |
| B. | solid and gaseous fuels |
| C. | liquid fuels that can be easily vaporized |
| D. | solid fuels only |
| Answer» A. solids and liquid fuels | |
| 69. |
If the intake air temperature of I.C. engine increases, its efficiency will |
| A. | increase |
| B. | decrease |
| C. | remain same |
| D. | unpredictable |
| Answer» B. decrease | |
| 70. |
All heat engines utilize |
| A. | low heat value of oil |
| B. | high heat value of oil |
| C. | net claorific value of oil |
| D. | calorific value of fuel |
| Answer» A. low heat value of oil | |
| 71. |
An engine indicator is used to determine the following |
| A. | speed |
| B. | temperature |
| C. | volume of cylinder |
| D. | m.e.p. and I.H.P. |
| Answer» D. m.e.p. and I.H.P. | |
| 72. |
Fuel oil consumption guarantees for I .C. engine are usually based on |
| A. | low heat value of oil |
| B. | high heat value of oil |
| C. | net calorific value of oil |
| D. | calorific value of fuel |
| Answer» B. high heat value of oil | |
| 73. |
Combustion in compression ignition engines is |
| A. | homogeneous |
| B. | heterogeneous |
| C. | both (a) and (b) |
| D. | laminar |
| Answer» B. heterogeneous | |
| 74. |
The air requirement of a petrol engine during starting compared to theoretical required for complete combustion is |
| A. | more |
| B. | loss |
| C. | same |
| D. | may be more or less depending on engine capacity |
| Answer» B. loss | |
| 75. |
Diesel fuel, compared to petrol is |
| A. | less difficult to ignite |
| B. | just about the same difficult to ignite |
| C. | more difficult to ignite |
| D. | highly ignitable |
| Answer» C. more difficult to ignite | |
| 76. |
When crude oil is heated, then which of the following hydrocarbon is given off first. |
| A. | kerosene |
| B. | gasoline |
| C. | paraffin |
| D. | natural gas. |
| Answer» D. natural gas. | |
| 77. |
The rating of a diesel engine, with increase in air-intlet temperature, will |
| A. | increase linearly |
| B. | decrease linearly |
| C. | increase parabolically |
| D. | decrease parabolically |
| Answer» B. decrease linearly | |
| 78. |
A 75 cc engine has following parameter as 75 cc |
| A. | fuel tank capacity |
| B. | lub oil capacity |
| C. | swept volume |
| D. | cylinder volume |
| Answer» C. swept volume | |
| 79. |
A heat engine utilises the |
| A. | calorific value of oil |
| B. | low heat value of |
| C. | high heat value of oil |
| D. | mean heat value of oil |
| Answer» C. high heat value of oil | |
| 80. |
Gaseous-fuel guarantees are based on |
| A. | calorific value of oil |
| B. | low heat value of oil |
| C. | high heat value of oil |
| D. | mean heat value of oil |
| Answer» B. low heat value of oil | |
| 81. |
Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads |
| A. | the friction is high |
| B. | the friction is unpredictable |
| C. | the small difference in cooling water temperature or in internal friction has a disproportionate effect |
| D. | the engine is rarely operated |
| Answer» C. the small difference in cooling water temperature or in internal friction has a disproportionate effect | |
| 82. |
Polymerisation is a chemical process in which molecules of a compound become |
| A. | larger |
| B. | slowed down |
| C. | smaller |
| D. | liquid |
| Answer» A. larger | |
| 83. |
Which of the following is the lightest and most volatile liquid fuel |
| A. | diesel |
| B. | kerosene |
| C. | fuel oil |
| D. | gasoline |
| Answer» D. gasoline | |
| 84. |
The theoretically correct air fuel ratio for petrol engine is of the order of |
| A. | 6 : 1 |
| B. | 9 : 1 |
| C. | 12 : 1 |
| D. | 15 : 1 |
| Answer» D. 15 : 1 | |
| 85. |
Air fuel ratio for idling speed of a petrol engine is approximately |
| A. | 1 : 1 |
| B. | 5 : 1 |
| C. | 10:1 |
| D. | 15 : 1 |
| Answer» C. 10:1 | |
| 86. |
Air fuel ratio at which a petrol engine can not work is |
| A. | 8 : 1 |
| B. | 10 : 1 |
| C. | 15 : 1 |
| D. | 20 : 1 and less |
| Answer» D. 20 : 1 and less | |
| 87. |
Advantage of gaseous fuel is that |
| A. | it can be stored easily |
| B. | it can mix easily with air |
| C. | it can displace more air from the engine |
| D. | all of the above |
| Answer» B. it can mix easily with air | |
| 88. |
Paraffins are in general represented by |
| A. | CnHn |
| B. | CnH2n |
| C. | CnH2n+2 |
| D. | CnH2n-6 |
| Answer» C. CnH2n+2 | |
| 89. |
Paraffins have molecular structure of |
| A. | chain saturated |
| B. | chain unsaturated |
| C. | ring saturated |
| D. | ring unsaturated |
| Answer» A. chain saturated | |
| 90. |
Olefins are represented by the formula |
| A. | CnH2n |
| B. | CnH2n+2 |
| C. | CnH2n-4 |
| D. | CnH2n-6 |
| Answer» A. CnH2n | |
| 91. |
Hydrocarbons are decomposed into smaller hydrocarbons by |
| A. | reforming |
| B. | refining |
| C. | cracking |
| D. | polymerization |
| Answer» C. cracking | |
| 92. |
The molecular structure of the straight-run gasoline is changed by |
| A. | cracking |
| B. | reforming |
| C. | reining |
| D. | boiling |
| Answer» B. reforming | |
| 93. |
For SI engines fuels most preferred are |
| A. | aromatics |
| B. | parafins |
| C. | olefins |
| D. | napthenes |
| Answer» A. aromatics | |
| 94. |
For CI engine fuels most preferred are |
| A. | napthenes |
| B. | paraffins |
| C. | olefins |
| D. | aromatics |
| Answer» B. paraffins | |
| 95. |
Octane number of iso-octane is |
| A. | 0 |
| B. | 30 |
| C. | 60 |
| D. | 100 |
| Answer» D. 100 | |
| 96. |
Ignition quality of diesel fuel is indicated by its |
| A. | octane number |
| B. | cetane number |
| C. | fash point |
| D. | fire point |
| Answer» B. cetane number | |
| 97. |
Flash point of fuel oil is |
| A. | minimum temperature to which1 oil is heated in order to give off inflammable vapours in Sufficient quantity to ignite momentarily when brought in contact with a flame |
| B. | temperature at which it solidifies or congeals |
| C. | temperature at which it catches fire without external aid |
| D. | indicated by 90% distillation temperature, i.e. when 90% of sample oil has distilled off |
| Answer» A. minimum temperature to which1 oil is heated in order to give off inflammable vapours in Sufficient quantity to ignite momentarily when brought in contact with a flame | |
| 98. |
Gasohol is a mixture of |
| A. | 90% ethanol + 10% gasoline |
| B. | 10% ethanol +90% gasoline |
| C. | 40% ethanol + 60% gasoline |
| D. | 50% ethanol +50% gasoline |
| Answer» B. 10% ethanol +90% gasoline | |
| 99. |
Stoichiometric air-fuel ratio of petrol is roughly |
| A. | 50:1 |
| B. | 25:1 |
| C. | 15:1 |
| D. | 1:1 |
| Answer» C. 15:1 | |
| 100. |
Venturi in the carburetor results in |
| A. | decrease of air velocity |
| B. | increase of air velocity |
| C. | decrease of fuel flow |
| D. | increase of manifold vacuum |
| Answer» B. increase of air velocity | |
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