MCQOPTIONS
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MCQOPTIONS
This section includes 513 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Mechanical efficiency is ratio of |
| A. | fp to bp |
| B. | fp to ip |
| C. | bp to ip |
| D. | ip to fp |
| Answer» D. ip to fp | |
| 52. |
Open combustion chambers in CI engines require |
| A. | high injection pressures |
| B. | accurate metering of fuel by the injection system |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» D. none of the above | |
| 53. |
Apart from hydrocarbons, the main pollutants in the engine exhaust are |
| A. | CO and CO2 |
| B. | CO2 and NOx |
| C. | CO and NOx |
| D. | CO2 and H2O |
| Answer» D. CO2 and H2O | |
| 54. |
The most accurate method of determining fp is by |
| A. | Willan's line |
| B. | Morse test |
| C. | measurement of brake and indicated power |
| D. | motoring test |
| Answer» D. motoring test | |
| 55. |
The heat given to cooling medium in IC engines is about |
| A. | 50-60% |
| B. | 30-40% |
| C. | 10-20% |
| D. | 60-70% |
| Answer» C. 10-20% | |
| 56. |
If the contact breaker gap is small, it results in |
| A. | advanced timing |
| B. | increased dwell |
| C. | rapid burning of the pointer gaps |
| D. | none of the above |
| Answer» D. none of the above | |
| 57. |
In a four-stroke IC engine cam shaft rotates at |
| A. | same speed as crankshaft |
| B. | twice the speed of crankshaft |
| C. | halt the speed of crankshaft |
| D. | none of the above |
| Answer» D. none of the above | |
| 58. |
The function of charcoal granules is to absorb: |
| A. | Water vapour |
| B. | Carbon monoxide |
| C. | Petrol Vapour |
| D. | Liquid petrol |
| Answer» D. Liquid petrol | |
| 59. |
Which of the following causes the photochemical smog? |
| A. | Excess O2 |
| B. | CO and CO2 |
| C. | Soot and particulate matter |
| D. | NOx and HC |
| Answer» E. | |
| 60. |
Direct system of cooling air is one which |
| A. | cooling water flows by gravity |
| B. | hot water is continuously cooled and circulated |
| C. | hot water is simply discharged |
| D. | water is allowed to evaporate in the cylinder jacket |
| Answer» D. water is allowed to evaporate in the cylinder jacket | |
| 61. |
Supercharging is normally done in |
| A. | racing cars |
| B. | marine engines |
| C. | automotive diesel engines |
| D. | none of the above |
| Answer» E. | |
| 62. |
Two wheelers without deflector type piston use |
| A. | loop scavenging |
| B. | unifow scavenging |
| C. | reverse flow scavenging |
| D. | cross scavenging |
| Answer» E. | |
| 63. |
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» D. Thermogenesis | |
| 64. |
The intake charge in a diesel engine consists of |
| A. | air alone |
| B. | air + lubricating oil |
| C. | air + fuel |
| D. | air + fuel + lubricating oil |
| Answer» B. air + lubricating oil | |
| 65. |
The first vehicle in India equipped with MPFI system in Indian automobile industry |
| A. | Tata Indica |
| B. | Daewoo Matiz |
| C. | Maruti Alto |
| D. | Chevrolet spark |
| Answer» C. Maruti Alto | |
| 66. |
The most perfect method of scavenging is |
| A. | cross scavenging |
| B. | uniflow scavenging |
| C. | loop scavenging |
| D. | reverse flow scavenging |
| Answer» C. loop scavenging | |
| 67. |
For the same peak pressure and heat input |
| A. | ƞOtto > ƞDual > ƞDiesel |
| B. | ƞOtto > ƞDiesel > ƞDual |
| C. | ƞDiesel > ƞDual > ƞOtto |
| D. | ƞDiesel > ƞOtto > ƞDual |
| Answer» D. ƞDiesel > ƞOtto > ƞDual | |
| 68. |
The advantages of the indirect injection combustion chambers are |
| A. | low injection pressure |
| B. | direction of spray is not critical |
| C. | both (a) and (b) |
| D. | good cold starting performance |
| Answer» D. good cold starting performance | |
| 69. |
Mean effective pressure at a given compression ratio is maximum when the air-fuel ratio is |
| A. | higher than stoichiometric |
| B. | lower than stoichiometric |
| C. | equal to stoichionetric |
| D. | none of the above |
| Answer» C. equal to stoichionetric | |
| 70. |
Method of governing used in petrol engine is |
| A. | hit and miss governing. |
| B. | quality governing |
| C. | quantity governing |
| D. | none of above |
| Answer» D. none of above | |
| 71. |
Advantage of two-stroke engine is |
| A. | more uniform torque |
| B. | lighter flywheel |
| C. | no valves |
| D. | all of the above |
| Answer» E. | |
| 72. |
The air requirement of a petrol engine during starting compared to theoretical required forcomplete combustion is |
| A. | more |
| B. | loss |
| C. | same |
| D. | may be more or less depending on engine capacity |
| Answer» C. same | |
| 73. |
Types of supercharger are |
| A. | reciprocating type |
| B. | gear type |
| C. | centrifugal type |
| D. | none of the above |
| Answer» D. none of the above | |
| 74. |
If turbochargers compressor is driven by |
| A. | exhaust gas turbine |
| B. | engine itself |
| C. | separate electrical motor |
| D. | none of the above |
| Answer» B. engine itself | |
| 75. |
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» D. exhaust blow down loss | |
| 76. |
Which of the following is the lightest and most volatile liquid fuel |
| A. | diesel |
| B. | kerosene |
| C. | fuel oil |
| D. | gasoline |
| Answer» E. | |
| 77. |
For a compressor process with variable specific heat the peak temperature and pressure are_______compared to constant specific heat |
| A. | lower |
| B. | higher |
| C. | no effect |
| D. | none of the above |
| Answer» B. higher | |
| 78. |
The normal range of, compression ratio for Otto cycle is |
| A. | 6 to 10 |
| B. | 2 to 4 |
| C. | >10 |
| D. | none of the above |
| Answer» B. 2 to 4 | |
| 79. |
Compression ratio in diesel engines is of the order of |
| A. | 5-7 |
| B. | 7 -10 |
| C. | 10 – 12 |
| D. | 14-20 |
| Answer» E. | |
| 80. |
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» E. | |
| 81. |
With increase in compression ratio, mechanical efficiency |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | compression ratio has nothing to do with ƞmech |
| Answer» B. decreases | |
| 82. |
Non-dispersive infra-red analyzer is widely accepted instrument for measuring |
| A. | NO |
| B. | HC |
| C. | CO |
| D. | CO2 |
| Answer» D. CO2 | |
| 83. |
Modern carburetors provide the correct quality of air-fuel mixture during |
| A. | starting |
| B. | idling |
| C. | cruising |
| D. | all conditions |
| Answer» E. | |
| 84. |
In air standard Diesel cycle at fixed r and fixed n |
| A. | ƞthermal increases with increase in heat addition and cut-off ratio |
| B. | ƞthermal decreases with increase in heat addition and cut-off ratio |
| C. | ƞthermal Remains the same with increase in heat addition and cut-off ratio |
| D. | none of the above |
| Answer» C. ƞthermal Remains the same with increase in heat addition and cut-off ratio | |
| 85. |
Which of the following is false statement. Some of the methods used to reduce diesel smoke are as follows |
| A. | using additives in the fuel |
| B. | engine derating i.e. reducing the maxi-mum flow of fuel |
| C. | increasing the compression ratio |
| D. | adherence to proper fuel specification |
| Answer» D. adherence to proper fuel specification | |
| 86. |
The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency iscalled |
| A. | net efficiency |
| B. | efficiency ratio |
| C. | relative efficiency |
| D. | overall efficiency |
| Answer» D. overall efficiency | |
| 87. |
Dwell is the time |
| A. | for which the points remain closed |
| B. | for which the points remain open |
| C. | time during which inlet and exhaust valves are open |
| D. | none of the above |
| Answer» B. for which the points remain open | |
| 88. |
If L is the stroke and N is the rpm, mean piston speed of two-stroke engine |
| A. | LN |
| B. | LN/2 |
| C. | 2LN |
| D. | none of the above |
| Answer» D. none of the above | |
| 89. |
Chemilumine scence analyzer is used for measuring |
| A. | NOx |
| B. | CO |
| C. | HC |
| D. | CO2 |
| Answer» B. CO | |
| 90. |
The catalyst used in the reduction converter is |
| A. | Copper |
| B. | Charcoal |
| C. | Rodium |
| D. | Platinum |
| Answer» D. Platinum | |
| 91. |
Ignition timing is adjusted by |
| A. | tachometer |
| B. | stroboscopic light |
| C. | stop watch |
| D. | accurate clock |
| Answer» C. stop watch | |
| 92. |
Crankcase ventilation, is provided |
| A. | to cool cylinder |
| B. | to cool crankcase |
| C. | to cool piston |
| D. | to remove blow by |
| Answer» E. | |
| 93. |
The liquid – vapour separator is located near the |
| A. | Fuel tank |
| B. | Carburettor |
| C. | Charcoal canister |
| D. | Purge valve |
| Answer» B. Carburettor | |
| 94. |
Paraffins are in general represented by |
| A. | CnHn |
| B. | CnH2n |
| C. | CnH2n+2 |
| D. | CnH2n-6 |
| Answer» D. CnH2n-6 | |
| 95. |
Brayton cycle is used in |
| A. | Ramjet engines |
| B. | gas turbines |
| C. | pulse jet engines |
| D. | Cl engines |
| Answer» C. pulse jet engines | |
| 96. |
In diesel engine the diesel fuel injected intc cylinder would burn instantly at about compressed air temperature of |
| A. | 250°C |
| B. | 500°C |
| C. | 1000°C |
| D. | 150CPC |
| Answer» D. 150CPC | |
| 97. |
The measurement of frictional power by Willans line is applicable only to |
| A. | SI engines at a particular speed |
| B. | CI engines at a particular speed |
| C. | any engine at a particular speed only |
| D. | none of the above |
| Answer» C. any engine at a particular speed only | |
| 98. |
For maximum thermal efficiency, the fuel-air mixture in SI engines should be |
| A. | lean |
| B. | rich |
| C. | stoichiometric |
| D. | may be rich or lean |
| Answer» B. rich | |
| 99. |
Polymerisation is a chemical process in which molecules of a compound become |
| A. | larger |
| B. | slowed down |
| C. | smaller |
| D. | liquid |
| Answer» B. slowed down | |
| 100. |
Spark timing other than minimum spark advance for best torque (MBT) results in |
| A. | less heat rejection |
| B. | more beat rejection |
| C. | no effect on heat rejection |
| D. | none of the above |
| Answer» C. no effect on heat rejection | |