MCQOPTIONS
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MCQOPTIONS
This section includes 286 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.
| 101. |
A diesel engine has compression ratio from |
| A. | 6 to 10 |
| B. | 10 to 15 |
| C. | 15 to 25 |
| D. | 25 to 40 |
| Answer» D. 25 to 40 | |
| 102. |
The compression ratio in petrol engines is kept low as compared to diesel engines because higher compression ratio in petrol engines would lead to pre-ignition of fuel. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 103. |
Which one of the following engines will have heavier flywheel than the remaining ones? |
| A. | 30 kW four-stroke petrol engine running at 1500 r.p.m. |
| B. | 30 kW two-stroke petrol engine running at 1500 r.p.m. |
| C. | 30 kW two-stroke diesel engine running at 750 r.p.m. |
| D. | 30 kW four-stroke diesel engine running at 750 r.p.m. |
| Answer» B. 30 kW two-stroke petrol engine running at 1500 r.p.m. | |
| 104. |
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 | |
| 105. |
The increase in intake temperature of internal combustion engines will __________ efficiency. |
| A. | have no effect on |
| B. | increase |
| C. | decrease |
| D. | None of these |
| Answer» D. None of these | |
| 106. |
A fission chain reaction in uranium can be developed |
| A. | by increasing the contents of U235 |
| B. | by slowing down fast neutrons so that U235 fission continues by slow neutron |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» D. none of these | |
| 107. |
The volumetric efficiency ofa well designed engine may be |
| A. | 30 to 40% |
| B. | 40 to 60% |
| C. | 60 to 70% |
| D. | 75 to 90% |
| Answer» E. | |
| 108. |
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. | |
| 109. |
The knocking tendency in spark ignition engines may be decreased by |
| A. | controlling the air-fuel mixture |
| B. | controlling the ignition timing |
| C. | controlling the exhaust temperature |
| D. | reducing the compression ratio |
| Answer» E. | |
| 110. |
Stoichiometric ratio is |
| A. | chemically correct air-fuel ratio by weight |
| B. | chemically correct air-fuel ratio by volume |
| C. | actual air-fuel ratio for maximum efficiency |
| D. | none of the above |
| Answer» C. actual air-fuel ratio for maximum efficiency | |
| 111. |
In a four stroke cycle petrol engine, the expansion |
| A. | starts at top dead centre and ends at bottom dead centre |
| B. | starts at 30° before top dead centre and ends at 50° before bottom dead centre |
| C. | starts at 30° after top dead centre and ends at 50° after bottom dead centre |
| D. | may start and end anywhere |
| Answer» C. starts at 30° after top dead centre and ends at 50° after bottom dead centre | |
| 112. |
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 | |
| 113. |
In a petrol engine, the charge is ignited with the help of a spark plug. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 114. |
The theoretically correct mixture of air and petrol is |
| A. | 10:1 |
| B. | 15:1 |
| C. | 20:1 |
| D. | 25:1 |
| Answer» C. 20:1 | |
| 115. |
Detonation is harmful due to |
| A. | increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine |
| B. | excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls |
| C. | high intensity of knock causes crankshaft vibration and the engine runs rough |
| D. | none of the above |
| Answer» E. | |
| 116. |
A two stroke cycle engine gives __________ the number of power strokes as compared to the four stroke cycle engine, at the same engine speed. |
| A. | half |
| B. | same |
| C. | double |
| D. | four times |
| Answer» D. four times | |
| 117. |
The basic requirement of a good combustion chamber is |
| A. | minimum turbulence |
| B. | low compression ratio |
| C. | high thermal efficiency and power output |
| D. | low volumetric efficiency |
| Answer» D. low volumetric efficiency | |
| 118. |
The thermal efficiency of diesel engines on weak mixtures is |
| A. | unaffected |
| B. | lower |
| C. | higher |
| D. | dependent on other factors |
| Answer» D. dependent on other factors | |
| 119. |
Morse test can be conducted for |
| A. | petrol engines |
| B. | diesel engines |
| C. | multi-cylinder engines |
| D. | all of these |
| Answer» D. all of these | |
| 120. |
The energy released during the fission of one atom of Uranium - 235 in million electron volts is about |
| A. | 100 |
| B. | 200 |
| C. | 300 |
| D. | 400 |
| Answer» C. 300 | |
| 121. |
U233 is produced |
| A. | artificially |
| B. | as basic raw material |
| C. | when thorium is irradiated by neutrons |
| D. | by fission of U238 |
| Answer» D. by fission of U238 | |
| 122. |
The detonation is also called knocking or pinking. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 123. |
In a four stroke cycle engine, the sequence of operations is |
| A. | suction, compression, expansion and exhaust |
| B. | suction, expansion, compression and exhaust |
| C. | expansion, compression, suction and exhaust |
| D. | compression, expansion, suction and exhaust |
| Answer» B. suction, expansion, compression and exhaust | |
| 124. |
Anti-knock for compression ignition engines is |
| A. | napthene |
| B. | tetra ethyl lead |
| C. | amyl nitrate |
| D. | hexadecane |
| Answer» D. hexadecane | |
| 125. |
A supercharged engine as compared to an ordinary engine |
| A. | requires smaller foundation |
| B. | is lighter |
| C. | consumes less lubricating oil |
| D. | all of these |
| Answer» E. | |
| 126. |
The two stroke cycle engines have lighter flywheel. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 127. |
A petrol engine, during suction stroke draws |
| A. | air only |
| B. | petrol only |
| C. | a mixture of petrol and air |
| D. | None of these |
| Answer» D. None of these | |
| 128. |
The function of a distributor in a coil ignition system of I.C. engines is |
| A. | to distribute spark |
| B. | to distribute power |
| C. | to distribute current |
| D. | to time the spark |
| Answer» E. | |
| 129. |
Diesel as compared to petrol is |
| A. | highly ignitable |
| B. | more difficult to ignite |
| C. | less difficult to ignite |
| D. | none of these |
| Answer» C. less difficult to ignite | |
| 130. |
The ratio of the heat equivalent to one kW hour to the heat in fuel per B.P. hour is termed as brake thermal efficiency. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 131. |
The maximum propulsive efficiency of a turbo-jet engine is at a speed of |
| A. | 1000 km/h |
| B. | 2000 km/h |
| C. | 2400 km/h |
| D. | 3000 km/h |
| Answer» D. 3000 km/h | |
| 132. |
An ignition coil in the spark ignition engines supplies __________ voltage to the spark plug. |
| A. | high |
| B. | low |
| C. | Can't say |
| D. | None of these |
| Answer» B. low | |
| 133. |
The overall efficiency is defined as the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 134. |
The ignition quality of diesel oil is expressed by |
| A. | cetane number |
| B. | octane number |
| C. | calorific value |
| D. | none of these |
| Answer» B. octane number | |
| 135. |
The relative efficiency of an I.C. engine is the ratio of the indicated thermal efficiency to the air standard efficiency. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 136. |
The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be |
| A. | 25% |
| B. | 50% |
| C. | 70% |
| D. | 100% |
| Answer» C. 70% | |
| 137. |
Which of the following statement is correct regarding petrol engines? |
| A. | A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure. |
| B. | The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug. |
| C. | The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition. |
| D. | all of the above |
| Answer» C. The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition. | |
| 138. |
In hit and miss governing, the fuel supply is cut-off completely during one or more number of cycles. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 139. |
In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the |
| A. | beginning of suction stroke |
| B. | end of suction stroke |
| C. | beginning of exhaust stroke |
| D. | end of exhaust stroke |
| Answer» B. end of suction stroke | |
| 140. |
The diesel engines are also known as __________ engines. |
| A. | compression ignition |
| B. | spark ignition |
| C. | Can't say |
| D. | None of these |
| Answer» B. spark ignition | |
| 141. |
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. | |
| 142. |
The detonating tendency in petrol engines increases with increase of compression ratio. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 143. |
Reactors for propulsion applications are designed for |
| A. | any form of uranium |
| B. | natura uranium |
| C. | enriched uranium |
| D. | plutonium |
| Answer» D. plutonium | |
| 144. |
In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will __________ the knocking tendency. |
| A. | not effect |
| B. | decrease |
| C. | increase |
| D. | None of these |
| Answer» D. None of these | |
| 145. |
The primary fuel used in nuclear power plants is |
| A. | U235 |
| B. | U238 |
| C. | Pu239 |
| D. | Pu233 |
| Answer» B. U238 | |
| 146. |
The secondary fuel used in nuclear power plants is |
| A. | U233 and Pu239 |
| B. | U235 and Th232 |
| C. | U235 and Pu238 |
| D. | U233 and Pu238 |
| Answer» B. U235 and Th232 | |
| 147. |
The brake power of a diesel engine, keeping other parameters constant, can be increased by |
| A. | decreasing the density of intake air |
| B. | increasing the temperature of intake air |
| C. | increasing the pressure of intake air |
| D. | decreasing the pressure of intake air |
| Answer» D. decreasing the pressure of intake air | |
| 148. |
In a four stroke cycle petrol engine, the inlet valve |
| A. | opens at top dead centre and closes at bottom dead centre |
| B. | opens at 20° before top dead centre and closes at 40° after bottom dead centre |
| C. | opens at 20° after top dead centre and closes at 20° before bottom dead centre id) may open or close anywhere |
| D. | None of these |
| Answer» C. opens at 20° after top dead centre and closes at 20° before bottom dead centre id) may open or close anywhere | |
| 149. |
The object of supercharging the engine is |
| A. | to reduce mass ofthe engine per brake power |
| B. | to reduce space occupied by the engine |
| C. | to increase the power output of an engine when greater power is required |
| D. | all ofthe above |
| Answer» E. | |
| 150. |
The normal heptane (C7H16) is given a rating of __________ octane number. |
| A. | 0 |
| B. | 50 |
| C. | 100 |
| D. | 120 |
| Answer» B. 50 | |