MCQOPTIONS
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MCQOPTIONS
This section includes 261 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.
| 51. |
The correct mixture strength (by weight) for petrol is about |
| A. | 14.6 : 1 |
| B. | 18.5 : 1 |
| C. | 20.4 : 1 |
| D. | 22.6 : 1 |
| Answer» B. 18.5 : 1 | |
| 52. |
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» D. More or less depending on power rating | |
| 53. |
The process of breaking up or a liquid into fine droplets by spraying is called |
| A. | Vaporisation |
| B. | Carburetion |
| C. | Ionization |
| D. | Atomization |
| Answer» E. | |
| 54. |
The correct sequence of the decreasing order of brake thermal efficiency of the three given basic types of engines is |
| A. | Four stroke C.I. engine, four stroke S.I. engine, two stroke S.I. engine |
| B. | Four stroke S.I. engine, four stroke C.I. engine, two stroke S.I. engine |
| C. | Four stroke C.I. engine, two stroke S.I. engine, four stroke S.I. engine |
| D. | Two stroke S.I. engine, four stroke S.I. engine, four stroke C.I. engine |
| Answer» B. Four stroke S.I. engine, four stroke C.I. engine, two stroke S.I. engine | |
| 55. |
The compensating jet in a carburettor supplies almost constant amount of petrol at all speeds because the |
| A. | Jet area is automatically varied depending on the suction |
| B. | The flow from the main jet is diverted to the compensating jet with increase in speed |
| C. | The diameter of the jet is constant and the discharge coefficient is invariant |
| D. | Flow is produced due to the static head in the float chamber |
| Answer» E. | |
| 56. |
The pressure at the end of compression in the case of diesel engine is of the order of |
| A. | 6 kg/cm |
| B. | 12 kg/cm |
| C. | 20 kg/cm |
| D. | 35 kg/cm |
| Answer» E. | |
| 57. |
The probability of knocking in diesel engines is increased by |
| A. | High self ignition temperature |
| B. | Low volatility |
| C. | Higher viscosity |
| D. | All of these |
| Answer» E. | |
| 58. |
If the temperature of intake air in internal combustion engine increases, then its efficiency will |
| A. | Remain same |
| B. | Decrease |
| C. | Increase |
| D. | None of these |
| Answer» C. Increase | |
| 59. |
If the intake air temperature of I.C. engine increases, its efficiency will |
| A. | Increase |
| B. | Decrease |
| C. | Remain same |
| D. | None of these |
| Answer» C. Remain same | |
| 60. |
The compression ignition engines are governed by |
| A. | Hit and miss governing |
| B. | Qualitative governing |
| C. | Quantitative governing |
| D. | Combination of (B) and (C) |
| Answer» C. Quantitative governing | |
| 61. |
The spark ignition engines are governed by |
| A. | Hit and miss governing |
| B. | Qualitative governing |
| C. | Quantitative governing |
| D. | Combination of (B) and (C) |
| Answer» D. Combination of (B) and (C) | |
| 62. |
In a four stroke cycle petrol engine, the charge is ignited at |
| A. | 30° before top dead center |
| B. | 30° after top dead center |
| C. | 30° before bottom dead center |
| D. | 30° after bottom dead center |
| Answer» B. 30° after top dead center | |
| 63. |
The increase of efficiency of a compression ignition engine, as the load decreases, is due to |
| A. | Higher maximum temperature |
| B. | Qualitative governing |
| C. | Quantitative governing |
| D. | Hit and miss governing |
| Answer» C. Quantitative governing | |
| 64. |
In the crankcase method of scavenging, the air pressure is produced by |
| A. | Supercharger |
| B. | Centrifugal pump |
| C. | Natural aspirator |
| D. | Movement of engine piston |
| Answer» E. | |
| 65. |
The output of a diesel engine can be increased without increasing the engine revolution or size in following way |
| A. | Feeding more fuel |
| B. | Heating incoming air |
| C. | Scavenging |
| D. | Supercharging |
| Answer» E. | |
| 66. |
Which of the following does not relate to a spark ignition engine? |
| A. | Ignition coil |
| B. | Spark plug |
| C. | Carburettor |
| D. | Fuel injector |
| Answer» E. | |
| 67. |
Which of the following does not relate to a compression ignition engine? |
| A. | Fuel pump |
| B. | Fuel injector |
| C. | Governor |
| D. | Carburettor |
| Answer» E. | |
| 68. |
Which one of the following event would reduce volumetric efficiency of a vertical compression ignition engine? |
| A. | Inlet valve closing after bottom dead center |
| B. | Inlet valve closing before bottom dead center |
| C. | Inlet valve opening before top dead center |
| D. | Exhaust valve closing after top dead center |
| Answer» C. Inlet valve opening before top dead center | |
| 69. |
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» E. | |
| 70. |
Theoretically, a four stroke cycle engine should develop _________ power as that of a two stroke cycle engine. |
| A. | Half |
| B. | Same |
| C. | Double |
| D. | Four times |
| Answer» B. Same | |
| 71. |
Thermal efficiency of a two stroke cycle engine is _________ a four stroke cycle engine. |
| A. | Equal to |
| B. | Less than |
| C. | Greater than |
| D. | None of these |
| Answer» C. Greater than | |
| 72. |
If V₁ is the jet velocity and V₀ is the vehicle velocity, then the propulsive efficiency of a rocket is given by |
| A. | [2(V₀/V₁)]/ [1 + (V₀/V₁)²] |
| B. | (V₀/V₁)/ [1 + (V₀/V₁)²] |
| C. | V₀/(V₀ + V₁) |
| D. | V₁/(V₀ + V₁) |
| Answer» B. (V₀/V₁)/ [1 + (V₀/V₁)²] | |
| 73. |
The working pressure and temperature inside the cylinder of an internal combustion engine is _________ as compared to a steam engine. |
| A. | Low |
| B. | Very low |
| C. | High |
| D. | Very high |
| Answer» E. | |
| 74. |
Flash point of fuel oil is |
| A. | Minimum temperature to which 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» B. Temperature at which it solidifies or congeals | |
| 75. |
The voltage required to produce a spark across the gap, between the sparking points is |
| A. | 2000 to 4000 volts |
| B. | 4000 to 6000 volts |
| C. | 6000 to 10,000 volts |
| D. | 10,000 to 12,000 volts |
| Answer» D. 10,000 to 12,000 volts | |
| 76. |
The following volume of air is required for consuming 1 liter of fuel by a four stroke engine |
| A. | 1 m3 |
| B. | 5 m3 |
| C. | 56 m3 |
| D. | 910 m3 |
| Answer» E. | |
| 77. |
The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft |
| A. | 1/2 |
| B. | 1 |
| C. | 2 |
| D. | 4 |
| Answer» D. 4 | |
| 78. |
Which of the following is not an intern’s combustion engine? |
| A. | 2-stroke petrol engine |
| B. | 4-stroke petrol engine |
| C. | Diesel engine |
| D. | Steam turbine |
| Answer» E. | |
| 79. |
The increase of cooling water temperature in petrol engine will _________ the knocking tendency. |
| A. | Not effect |
| B. | Decrease |
| C. | Increase |
| D. | None of these |
| Answer» D. None of these | |
| 80. |
In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will _________ the knocking tendency. |
| A. | Not effected |
| B. | Decrease |
| C. | Increase |
| D. | None of these |
| Answer» D. None of these | |
| 81. |
In petrol engines, advancing of the spark timing will _________ the knocking tendency. |
| A. | Not effect |
| B. | Decrease |
| C. | Increase |
| D. | None of these |
| Answer» D. None of these | |
| 82. |
The higher combustion chamber wall temperature in compression ignition engines will _________ knocking tendency. |
| A. | Increase |
| B. | Reduce |
| C. | Not effect |
| D. | None of these |
| Answer» C. Not effect | |
| 83. |
The advancing of spark timing in spark ignition engines will _________ knocking tendency. |
| A. | Increase |
| B. | Reduce |
| C. | Not effect |
| D. | None of these |
| Answer» B. Reduce | |
| 84. |
The power actually developed by the engine cylinder of an I.C. engine is known as |
| A. | Theoretical power |
| B. | Actual power |
| C. | Indicated power |
| D. | None of these |
| Answer» D. None of these | |
| 85. |
The loud pulsating noise heard within the cylinder of an internal combustion engine is known as |
| A. | Detonation |
| B. | Turbulence |
| C. | Pre-ignition |
| D. | Supercharging |
| Answer» B. Turbulence | |
| 86. |
The mechanical efficiency (ηm) of the engine is given by |
| A. | ηm = B.P/I.P |
| B. | ηm = I.P/B.P |
| C. | ηm = (B.P × I.P)/100 |
| D. | None of these |
| Answer» B. ηm = I.P/B.P | |
| 87. |
Which of the following statement is correct regarding normal cetane? |
| A. | It is a standard fuel used for knock rating of diesel engines |
| B. | Its chemical name is normal hexadecane |
| C. | It has long carbon chain structure |
| D. | All of the above |
| Answer» E. | |
| 88. |
A diesel engine is _________ as compared to petrol engine, both running at rated load. |
| A. | Equally efficient |
| B. | Less efficient |
| C. | More efficient |
| D. | None of these |
| Answer» D. None of these | |
| 89. |
Antiknock for compression ignition engines is |
| A. | Napthene |
| B. | Tetra ethyl lead |
| C. | Amyl nitrate |
| D. | Hexadecane |
| Answer» D. Hexadecane | |
| 90. |
Combustion in compression ignition engines is |
| A. | Homogeneous |
| B. | Heterogeneous |
| C. | Both (A) and (B) |
| D. | Laminar |
| Answer» C. Both (A) and (B) | |
| 91. |
The combustion in compression ignition engines is |
| A. | Homogeneous |
| B. | Heterogeneous |
| C. | Both (A) and (B) |
| D. | None of these |
| Answer» C. Both (A) and (B) | |
| 92. |
High speed compression engines operate on |
| A. | Otto cycle |
| B. | Diesel cycle |
| C. | Dual combustion cycle |
| D. | All of these |
| Answer» D. All of these | |
| 93. |
The reference fuels for knock rating of spark ignition engines would include |
| A. | Iso-octane and alpha-methyl naphthalene |
| B. | Normal octane and aniline |
| C. | Iso-octane and normal hexane |
| D. | Normal heptane and iso-octane |
| Answer» E. | |
| 94. |
Compression loss in I.C engines occurs due to |
| A. | Leaking piston rings |
| B. | Use of thick head gasket |
| C. | Clogged air inlet slots |
| D. | All of the above |
| Answer» E. | |
| 95. |
The volumetric efficiency of a well designed engine may be |
| A. | 30 to 40% |
| B. | 40 to 60% |
| C. | 60 to 70% |
| D. | 75 to 90% |
| Answer» E. | |
| 96. |
In a four stroke cycle petrol engine, the expansion |
| A. | Starts at top dead center and ends at bottom dead center |
| B. | Starts at 30° before top dead center and ends at 50° before bottom dead center |
| C. | Starts at 30° after top dead center and ends at 50° after bottom dead center |
| D. | May start and end anywhere |
| Answer» C. Starts at 30° after top dead center and ends at 50° after bottom dead center | |
| 97. |
Air fuel ratio at which a petrol engine cannot work is |
| A. | 8 : 1 |
| B. | 10 : 1 |
| C. | 15 : 1 |
| D. | 20 : 1 and less |
| Answer» E. | |
| 98. |
Supercharging is the process of supplying the intake air to the engine cylinder at a density _________ the density of the surrounding atmosphere. |
| A. | Equal to |
| B. | Less than |
| C. | Greater than |
| D. | None of these |
| Answer» D. None of these | |
| 99. |
A diesel engine as compared to petrol engine (both running and rated load) is |
| A. | More efficient |
| B. | Less efficient |
| C. | Equally efficient |
| D. | Other factors will decide it |
| Answer» B. Less efficient | |
| 100. |
In a petrol engine, if diesel is used, then the engine will |
| A. | Not run |
| B. | Run more efficiently |
| C. | Run at high speed |
| D. | Explode |
| Answer» B. Run more efficiently | |