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.
| 201. |
Alpha-methyl-naphthalene (C₁₁ H₁₀) has a cetane number of |
| A. | 0 |
| B. | 50 |
| C. | 100 |
| D. | 120 |
| Answer» B. 50 | |
| 202. |
The cetane (C₁₆H₃₄) which is a straight chain paraffin, is assigned a cetane number of |
| A. | 0 |
| B. | 50 |
| C. | 100 |
| D. | 120 |
| Answer» D. 120 | |
| 203. |
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 | |
| 204. |
Engine pistons are usually made of aluminium alloy because it |
| A. | Is lighter |
| B. | Wear is less |
| C. | Absorbs shocks |
| D. | Is stronger |
| Answer» B. Wear is less | |
| 205. |
In loop scavenging, the top of the piston is |
| A. | flat |
| B. | contoured |
| C. | slanted |
| D. | depressed |
| Answer» C. slanted | |
| 206. |
In a naturally aspirated diesel engine, the air is supplied by |
| A. | a supercharger |
| B. | a centrifugal blower |
| C. | a vacuum chamber |
| D. | an injection tube |
| Answer» D. an injection tube | |
| 207. |
A stoichiometric air-fuel ratio is |
| A. | chemically correct mixture |
| B. | lean mixture |
| C. | rich mixture for idling |
| D. | rich mixture for over loads |
| Answer» B. lean mixture | |
| 208. |
Volatility of diesel 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. | it catches fire without external aid |
| D. | indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off |
| Answer» E. | |
| 209. |
The air-fuel ratio in petrol engines-is controlled by |
| A. | controlling valve opening/closing |
| B. | governing |
| C. | injection |
| D. | carburettion |
| Answer» E. | |
| 210. |
The knock in diesel engine occurs due to |
| A. | instantaneous and rapid burning of the first part of the charge |
| B. | instantaneous atuo iginition of last part of charge |
| C. | delayed burning of the first part of the charge |
| D. | reduction of delay period |
| Answer» B. instantaneous atuo iginition of last part of charge | |
| 211. |
Diesel engine can work on very lean air fuel ratio of the order of 30 : 1. A petrol engine can also work on such a lean ratio provided |
| A. | it is properly designed |
| B. | best quality fuel is used |
| C. | can not work as it is impossible |
| D. | flywheel size is proper |
| Answer» D. flywheel size is proper | |
| 212. |
A 5 BHP engine running at full load would consume diesel of the order of |
| A. | 0.3 kg/hr |
| B. | 1 kg/hr |
| C. | 3 kg/hr |
| D. | 5 kg/hr |
| Answer» C. 3 kg/hr | |
| 213. |
Pour point of fuel oil is the |
| 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. | it catches fire without external aid |
| D. | indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off |
| Answer» C. it catches fire without external aid | |
| 214. |
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» E. | |
| 215. |
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» D. 15 : 1 | |
| 216. |
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» E. | |
| 217. |
Installation of supercharger on a four-cycle diesel engine can result in the following percentage increase in power |
| A. | upto 25% |
| B. | upto 35% |
| C. | upto 50% |
| D. | upto 100% |
| Answer» E. | |
| 218. |
For the same power developed in I.C. engines, the cheaper system is |
| A. | naturally aspirated |
| B. | supercharged |
| C. | centrifugal pump |
| D. | turbo charger |
| Answer» C. centrifugal pump | |
| 219. |
The mean effective pressure obtained from engine indicator indicates the |
| A. | maximum pressure developed |
| B. | minimum pressure |
| C. | instantaneous pressure at any instant |
| D. | average pressure. |
| Answer» E. | |
| 220. |
The minimum cranking speed in case of petrol engine is about |
| A. | half the operating speed |
| B. | one-fourth of operating speed |
| C. | 250-300 rpm |
| D. | 60-80 rpm |
| Answer» E. | |
| 221. |
Supercharging is essential in |
| A. | diesel engines |
| B. | gas turbines |
| C. | petrol engines |
| D. | aircraft engines |
| Answer» E. | |
| 222. |
The operation of forcing additional air under pressure in the engine cylinder is known as |
| A. | scavenging |
| B. | turbulence |
| C. | supercharging |
| D. | pre-ignition |
| Answer» D. pre-ignition | |
| 223. |
The reason for supercharging in any engine is to |
| A. | increase Power |
| B. | increase power |
| C. | reduce weight and bulk for a given out-put |
| D. | effect fuel economy |
| Answer» D. effect fuel economy | |
| 224. |
Pick up the wrong statement about supercharging |
| A. | supercharging reduces knocking in diesel engines |
| B. | there can be limited supercharging in petrol engines because of detonation |
| C. | supercharging at high altitudes is essential |
| D. | supercharging results in fuel economy |
| Answer» E. | |
| 225. |
The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be |
| A. | higher |
| B. | lower |
| C. | remain unaffected |
| D. | unpredictable |
| Answer» B. lower | |
| 226. |
In a cycle, the spark lasts roughly for |
| A. | 1 sec |
| B. | 0.1 sec |
| C. | 0.01 sec |
| D. | 0.0O1 sec |
| Answer» E. | |
| 227. |
The size of inlet valve of.an engine in comparison to exhaust valve is |
| A. | more |
| B. | less |
| C. | same |
| D. | more/less depending on capacity of engine |
| Answer» C. same | |
| 228. |
A diesel engine as compared to petrol engine (both running ar rated load) is |
| A. | more efficient |
| B. | less efficient |
| C. | equally efficient |
| D. | unperdictable |
| Answer» B. less efficient | |
| 229. |
The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is |
| A. | same |
| B. | more |
| C. | less |
| D. | less or more depending on operating conditions |
| Answer» C. less | |
| 230. |
The cam shaft of a four stroke I.C. engine running at 1500 rmp will run at |
| A. | 1500 rpm |
| B. | 750 rpm |
| C. | 3000 rpm |
| D. | any value independent of engine speed |
| Answer» C. 3000 rpm | |
| 231. |
In diesel engine, the compression ratio in comparison to expansion ratio is |
| A. | same |
| B. | less |
| C. | more |
| D. | variable |
| Answer» D. variable | |
| 232. |
The term scavenging is generally associated with |
| A. | 2-stroke cycle engines |
| B. | 4-stroke cycle engines |
| C. | aeroplane engines |
| D. | high efficiency engines. |
| Answer» E. | |
| 233. |
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» C. high heat value of oil | |
| 234. |
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» D. mean heat value of oil | |
| 235. |
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» D. cylinder volume | |
| 236. |
In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of |
| A. | 250°C |
| B. | 500°C |
| C. | 1000°C |
| D. | 150CPC |
| Answer» D. 150CPC | |
| 237. |
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» D. highly ignitable | |
| 238. |
In a typical medium speed, 4-stroke cycle diesel engine |
| A. | fuelinjection 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 deac center |
| D. | may start and end anywhere |
| Answer» B. fuel injection starts at top dead center and ends at 20° after top dead center | |
| 239. |
The accunmulation of carbon in a cylinder results in increase of |
| A. | clearance volume |
| B. | volumetric efficiency |
| C. | ignition time |
| D. | effective compression ratio |
| Answer» E. | |
| 240. |
Most high speed compression engines operate on |
| A. | Diesel cycle |
| B. | Otto cycle |
| C. | Dual combustion cycle |
| D. | Special type of air cycle |
| Answer» D. Special type of air cycle | |
| 241. |
In a typical medium speed 4-stroke cycle diesel engine |
| A. | compression starts at 35° after bottom dead center and ends at top dead center |
| B. | compression starts at bottom dead center and ends at top dead center |
| C. | compression starts at 10° before bottom dead center and, ends just before top dead center |
| D. | may start and end anywhere |
| Answer» B. compression starts at bottom dead center and ends at top dead center | |
| 242. |
It the temperature of intake air in IC engines is lowered, then its efficiency will |
| A. | increase |
| B. | decrease |
| C. | remain same |
| D. | increase upto certain limit and then decrease |
| Answer» B. decrease | |
| 243. |
The output of a diesel engine can be increased without increasing the engine revolution or size in following way |
| A. | feeding more fuel |
| B. | increasing flywheel size |
| C. | heating incoming air |
| D. | supercharging. |
| Answer» E. | |
| 244. |
Which of the following is not an interns combustion engine |
| A. | 2-stroke petrol engine |
| B. | 4-stroke petrol engine |
| C. | diesel engine |
| D. | steam turbine. |
| Answer» E. | |
| 245. |
The inlet value of a four stroke cycle I.C engine remains open for nearly |
| A. | 180° |
| B. | 125° |
| C. | 235° |
| D. | 200° |
| Answer» D. 200° | |
| 246. |
The air requirement of a petrol engine during starting compared to theoretical airequired for complete combustion is |
| A. | more |
| B. | loss |
| C. | same |
| D. | may be more or less depending on engine capacity |
| Answer» C. same | |
| 247. |
Crankcase explosion in I.C. engines usuall occurs as |
| A. | first a mild explosion followed by a bi explosion |
| B. | first a big explosion followed by a mil explosion |
| C. | both mild and big explosions occi simultaneously |
| D. | never occurs |
| Answer» B. first a big explosion followed by a mil explosion | |
| 248. |
The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed |
| A. | 80°C |
| B. | 120°C |
| C. | 180°C |
| D. | 240°C |
| Answer» D. 240°C | |
| 249. |
The specific fuel consumption per BHP hour for diesel engine is approximately |
| A. | 0.15 kg |
| B. | 0.2 kg |
| C. | 0.25 kg |
| D. | 0.3 kg |
| Answer» C. 0.25 kg | |
| 250. |
The thermal efficiecny of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will |
| A. | increase |
| B. | decrease |
| C. | be independent |
| D. | may increase or decrease depending on other factors |
| Answer» C. be independent | |