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.
| 151. |
The slowing down of fast neutrons is desirable because slow moving neutrons are more effective than fast neutrons in triggering fission. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 152. |
The air standard efficiency ofan I.C. engine is given by (where r = Compression ratio, and γ = Ratio of specific heats) |
| A. | 1 - rγ - 1 |
| B. | 1 + rγ - 1 |
| C. | 1 - (1/rγ - 1) |
| D. | none of these |
| Answer» D. none of these | |
| 153. |
Nuclear reactors are used |
| A. | to produce heat for thermoelectric power |
| B. | to produce fissionable material |
| C. | to propel ships, submarines, aircrafts |
| D. | all of these |
| Answer» E. | |
| 154. |
The exhaust valve in a four stroke cycle petrol engine |
| A. | opens at 50° before bottom dead centre and closes at 15° after top dead centre |
| B. | opens at bottom dead centre and closes at top dead centre |
| C. | opens at 50° after bottom dead centre and closes at 15° before top dead centre |
| D. | may open and close anywhere |
| Answer» B. opens at bottom dead centre and closes at top dead centre | |
| 155. |
A moderator generally used in nuclear power plants is |
| A. | graphite |
| B. | heavy water |
| C. | concrete |
| D. | graphite and concrete |
| Answer» E. | |
| 156. |
The effective inhibitor of pre-ignition is |
| A. | alcohol |
| B. | water |
| C. | lead |
| D. | none of these |
| Answer» C. lead | |
| 157. |
In a four stroke cycle petrol engine, the charge is ignited at |
| A. | 30° before top dead centre |
| B. | 30° after top dead centre |
| C. | 30° before bottom dead centre |
| D. | 30° after bottom dead centre |
| Answer» B. 30° after top dead centre | |
| 158. |
A moderator, in nuclear power plants, is a medium introduced into the fuel mass in order to |
| A. | slow down the speed of fast moving neutrons |
| B. | control the reaction |
| C. | reduce the temperature |
| D. | extract heat from nuclear reaction |
| Answer» B. control the reaction | |
| 159. |
In a diesel engine, the duration between the time of injection and ignition, is known as |
| A. | pre-ignition period |
| B. | delay period |
| C. | period of ignition |
| D. | burning period |
| Answer» C. period of ignition | |
| 160. |
If the fuel is rich in fissionable material, the reactor can be made more compact than if the percentage of fissionable atoms is small. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 161. |
Where reactor operation is designed with fast neutrons such as in reactors using highly enriched fuel, the moderator used is |
| A. | heavy water |
| B. | graphite |
| C. | carbon dioxide |
| D. | no moderator is needed |
| Answer» E. | |
| 162. |
In a four stroke engine, the working cycle is completed in |
| A. | one revolution of the crankshaft |
| B. | two revolutions of the crankshaft |
| C. | three revolutions of the crankshaft |
| D. | four revolutions of the crankshaft |
| Answer» C. three revolutions of the crankshaft | |
| 163. |
Pre-ignition is caused by the spontantaneous combustion of the mixture before the end of the compression stroke, and is due to |
| A. | cylinder walls being too hot |
| B. | overheated spark plug points |
| C. | red hot carbon deposits on cylinder walls |
| D. | any one of these |
| Answer» E. | |
| 164. |
Reflector in nuclear power plants __________ neutron leakage. |
| A. | increases |
| B. | decreases |
| C. | have no effect on |
| D. | None of these |
| Answer» C. have no effect on | |
| 165. |
In open combustion chamber in diesel engines, the shape and layout of the piston crown, the inlet port and the valve produce the turbulent effect of fuel mixture. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 166. |
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 | |
| 167. |
In diesel engines, the ignition takes place due to the heat produced in the engine cylinder at the end of compression. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 168. |
The __________ engines can work on very lean mixture of fuel. |
| A. | spark ignition |
| B. | compression ignition |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 169. |
The fuel valve in a four stroke cycle diesel engine |
| A. | opens at 15° after top dead centre and closes at 20° before bottom dead centre |
| B. | opens at 15° before top dead centre and closes at 20° after top dead centre |
| C. | opens at top dead centre and closes at bottom dead centre |
| D. | may open and close anywhere |
| Answer» C. opens at top dead centre and closes at bottom dead centre | |
| 170. |
A long delay period in compression ignition engines gives a more rapid rise in pressure which causes knocking. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 171. |
In nuclear power plants, due to reflector, less fuel is needed to generate sufficient neutrons to sustain a chain reaction. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 172. |
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 | |
| 173. |
The ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time is called |
| A. | mechanical efficiency |
| B. | overall efficiency |
| C. | indicated thermal efficiency |
| D. | volumetric efficiency |
| Answer» C. indicated thermal efficiency | |
| 174. |
A two stroke cycle engine occupies larger floor area than a four stroke cycle engine. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 175. |
A two stroke cycle engine gives __________ mechanical efficiency than a four stroke cycle engine. |
| A. | higher |
| B. | lower |
| C. | Can't say |
| D. | None of these |
| Answer» B. lower | |
| 176. |
During suction stroke of a four stroke petrol engine, the inlet valve opens and the charge is sucked into the cylinder as the piston moves upwards from the bottom dead centre. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 177. |
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 | |
| 178. |
The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in metres, N = Speed of engine in r.p.m., S - Spring balance reading in newtons, D = Dia. of brake drum in metres, and d = Dia. of rope in metres) |
| A. | B.P = (Wl × 2πN)/60 watts |
| B. | B.P = [(W - S) πDN]/60 watts |
| C. | B.P = [(W - S) π (D + d) N]/60 watts |
| D. | all of these |
| Answer» E. | |
| 179. |
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 | |
| 180. |
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 | |
| 181. |
In compression ignition engines, swirl denotes a |
| A. | haphazard motion of the gases in the chamber |
| B. | rotary motion of the gases in the chamber |
| C. | radial motion of the gases in the chamber |
| D. | none of the above |
| Answer» C. radial motion of the gases in the chamber | |
| 182. |
In diesel engines, the fuel is injected in the form of very fine spray, into the engine cylinder, which gets ignited due to high temperature of the compressed air. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 183. |
In petrol engines, the delay period is of the order of |
| A. | 0.001 second |
| B. | 0.002 second |
| C. | 0.003 second |
| D. | 0.004 second |
| Answer» C. 0.003 second | |
| 184. |
In petrol engines, using a fixed octane rating fuel, the increase in engine speed will decrease the knocking tendency. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 185. |
In a four stroke cycle petrol engine, , the compression |
| A. | starts at 40° after bottom dead centre and ends at 30° before top dead centre |
| B. | starts at 40° before bottom dead centre and ends at 30° after bottom dead centre |
| C. | starts at bottom dead centre and ends at top dead centre |
| D. | may start and end anywhere |
| Answer» B. starts at 40° before bottom dead centre and ends at 30° after bottom dead centre | |
| 186. |
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 | |
| 187. |
Spark plugs in automobiles generally have a gap between |
| A. | 0.3 to 0.7 mm |
| B. | 0.2 to 0.8 mm |
| C. | 0.4 to 0.9 mm |
| D. | 0.6 to 1.8 mm |
| Answer» E. | |
| 188. |
The delay period in oil engines increases with increase in the speed of engine. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 189. |
The fuels in order of decreasing knock tendency for spark ignition engines are |
| A. | paraffins, aromatics, napthenes |
| B. | paraffins, napthenes, aromatics |
| C. | napthenes, aromatics, paraffins |
| D. | napthenes, paraffins, aromatics |
| Answer» C. napthenes, aromatics, paraffins | |
| 190. |
In a four stroke cycle petrol engine, the charge is compressed when both the valves (i.e. inlet valve and exit valve) are closed, |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 191. |
The purpose of testing an internal combustion engine is |
| A. | to determine the information, which can not be obtained by calculations |
| B. | to conform the data used in design, the validity of which may be doubtful |
| C. | to satisfy the customer regarding the performance of the engine |
| D. | all of the above |
| Answer» E. | |
| 192. |
The octane number of petrol, generally available, is |
| A. | 20 to 40 |
| B. | 40 to 60 |
| C. | 60 to 80 |
| D. | 80 to 100 |
| Answer» E. | |
| 193. |
The indicated power for multi-cylinder engine will be same as that of a single cylinder engine. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 194. |
The thermal efficiency of diesel engines is about |
| A. | 15% |
| B. | 30% |
| C. | 50% |
| D. | 70% |
| Answer» E. | |
| 195. |
Morse test is used to determine the I.P. of a |
| A. | single cylinder petrol engine |
| B. | four stroke engine |
| C. | single cylinder diesel engine |
| D. | multi-cylinder engine |
| Answer» E. | |
| 196. |
The cetane number of diesel oil, generally available, is |
| A. | 20 to 25 |
| B. | 25 to 30 |
| C. | 30 to 40 |
| D. | 40 to 55 |
| Answer» E. | |
| 197. |
The knocking tendency in compression ignition engines for a given fuel will be |
| A. | enhanced by decreasing compression ratio |
| B. | enhanced by increasing compression ratio |
| C. | dependent on other factors |
| D. | none of the above |
| Answer» B. enhanced by increasing compression ratio | |
| 198. |
The expansion of fuel in a four stroke cycle diesel engine |
| A. | starts at 15° before top dead centre and ends at 30° after top dead centre |
| B. | starts at top dead centre and ends at 30° after top dead centre |
| C. | starts at 15° after top dead centre and ends at 30° before bottom dead centre |
| D. | may start and end anywhere |
| Answer» D. may start and end anywhere | |
| 199. |
A petrol engine has compression ratio from |
| A. | 6 to 10 |
| B. | 10 to 15 |
| C. | 15 to 25 |
| D. | 25 to 40 |
| Answer» B. 10 to 15 | |
| 200. |
In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then __________ is employed. |
| A. | fuel pump |
| B. | injector |
| C. | carburettor |
| D. | none of these |
| Answer» D. none of these | |