MCQOPTIONS
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MCQOPTIONS
This section includes 327 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. |
Standard air is the air at |
| A. | Atmospheric conditions at any specific location |
| B. | 20°C and 1 kg/cm² and relative humidity 36% |
| C. | 0°C and standard atmospheric conditions |
| D. | 15°C and 1 kg/cm² |
| Answer» C. 0°C and standard atmospheric conditions | |
| 202. |
Free air is the air at |
| A. | Atmospheric conditions at any specific location |
| B. | 20°C and 1 kg/cm² and relative humidity of 36% |
| C. | 0°C and standard atmospheric conditions |
| D. | 15°C and 1 kg/cm² |
| Answer» B. 20°C and 1 kg/cm² and relative humidity of 36% | |
| 203. |
The work-done on a compressor will be minimum if air is taken from |
| A. | The atmosphere |
| B. | A source at 0° C |
| C. | A source of low temperature air |
| D. | A source of high temperature air |
| Answer» D. A source of high temperature air | |
| 204. |
In a double acting compressor, the air is compressed |
| A. | In one cylinder |
| B. | In two cylinders |
| C. | In a single cylinder on both sides of the piston |
| D. | In two cylinders on both sides of the piston |
| Answer» D. In two cylinders on both sides of the piston | |
| 205. |
In a closed cycle gas turbine, the air is compressed |
| A. | Isothermally |
| B. | Polytropically |
| C. | Isentropically |
| D. | None of these |
| Answer» D. None of these | |
| 206. |
The maximum delivery pressure in a rotary air compressor is |
| A. | 10 bar |
| B. | 20 bar |
| C. | 30 bar |
| D. | 50 bar |
| Answer» B. 20 bar | |
| 207. |
Propulsion efficiency of the following order is obtained in practice |
| A. | 34% |
| B. | 50% |
| C. | 60% |
| D. | 72% |
| Answer» D. 72% | |
| 208. |
The type of rotary compressor used in aeroplanes, is of |
| A. | Centrifugal type |
| B. | Axial flow type |
| C. | Radial flow type |
| D. | None of these |
| Answer» C. Radial flow type | |
| 209. |
Isothermal compression though most efficient, but is not practicable because |
| A. | It requires very big cylinder |
| B. | It does not increase pressure much |
| C. | It is impossible in practice |
| D. | Compressor has to run at very slow speed to achieve it |
| Answer» E. | |
| 210. |
A jet engine has |
| A. | No propeller |
| B. | Propeller in front |
| C. | Propeller at back |
| D. | Propeller on the top |
| Answer» B. Propeller in front | |
| 211. |
The capacity of a compressor is 5 m/min refers to |
| A. | Standard air |
| B. | Free air |
| C. | Compressed air |
| D. | Compressed air at delivery pressure |
| Answer» C. Compressed air | |
| 212. |
What will be the volume of air at 327°C if its volume at 27°C is 1.5 m³/ mt? |
| A. | 3 m³/ mt. |
| B. | 1.5 m³/ mt. |
| C. | 18 m³/ mt. |
| D. | 6 m³/ mt. |
| Answer» B. 1.5 m³/ mt. | |
| 213. |
The overall thermal efficiency of an ideal gas turbine plant is (where r = Pressure ratio) |
| A. | r ɣ-1 |
| B. | 1 - r ɣ-1 |
| C. | 1 - (1/r) ɣ-1/ɣ |
| D. | 1 - (1/r) ɣ/ɣ-1 |
| Answer» D. 1 - (1/r) ɣ/ɣ-1 | |
| 214. |
In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in ________ of the piston. |
| A. | One stroke |
| B. | Two strokes |
| C. | Three strokes |
| D. | Four strokes |
| Answer» C. Three strokes | |
| 215. |
The ratio of isentropic work to Euler’s work is known as |
| A. | Compressor efficiency |
| B. | Isentropic efficiency |
| C. | Euler |
| D. | Pressure coefficient |
| Answer» E. | |
| 216. |
The ratio of isentropic work to Euler work is known as |
| A. | Pressure coefficient |
| B. | Work coefficient |
| C. | Polytropic reaction |
| D. | Slip factor |
| Answer» B. Work coefficient | |
| 217. |
The ratio of the net work obtained from the gas turbine plant to the turbine work is known as |
| A. | Compression ratio |
| B. | Work ratio |
| C. | Pressure ratio |
| D. | None of these |
| Answer» C. Pressure ratio | |
| 218. |
A turboprop is preferred to turbojet because |
| A. | It has high propulsive efficiency at high speeds |
| B. | It can fly at supersonic speeds |
| C. | It can fly at high elevations |
| D. | It has high power for take off |
| Answer» E. | |
| 219. |
In a jet propulsion |
| A. | The propulsive matter is ejected from within the propelled body |
| B. | The propulsive matter is caused to flow around the propelled body |
| C. | Its functioning does not depend upon presence of air |
| D. | None of the above |
| Answer» C. Its functioning does not depend upon presence of air | |
| 220. |
The maximum temperature in a gas turbine is |
| A. | 200°C |
| B. | 500°C |
| C. | 700°C |
| D. | 1000°C |
| Answer» D. 1000°C | |
| 221. |
The hottest point in a gas turbine is |
| A. | at the base |
| B. | at the tip |
| C. | in the center |
| D. | between ~ to i of the blade height |
| Answer» E. | |
| 222. |
The compression ratio for the compressor is always _________ unity. |
| A. | Equal to |
| B. | Less than |
| C. | More than |
| D. | None of these |
| Answer» D. None of these | |
| 223. |
The efficiency of jet engine is |
| A. | higher at ground |
| B. | higher at high altitudes |
| C. | same at all altitudes |
| D. | higher at high speed |
| Answer» C. same at all altitudes | |
| 224. |
The compression ratio in a jet engine varies proportional to |
| A. | speed |
| B. | altitude |
| C. | Vspeed |
| D. | does not Vary. |
| Answer» B. altitude | |
| 225. |
Pressure ratio in gas turbines is the ratio of |
| A. | compressor pressure ratio |
| B. | highest pressure to exhaust pressure |
| C. | inlet pressure to exhaust pressure |
| D. | pressures across the turbine |
| Answer» C. inlet pressure to exhaust pressure | |
| 226. |
Turbofan engine employs |
| A. | one air stream |
| B. | two or more air streams |
| C. | no air stream |
| D. | solid fuel firing |
| Answer» C. no air stream | |
| 227. |
In turbo fan engine, the jet velocity as compared to turbo-jet engine is |
| A. | less |
| B. | more |
| C. | same |
| D. | may be less or more depening upon speed |
| Answer» B. more | |
| 228. |
Which of the following plants is smallest and lightest for genrating a given amount of power |
| A. | steam power plant |
| B. | petrol engine |
| C. | diesel engine |
| D. | gas turbine plant. |
| Answer» E. | |
| 229. |
Ram-jet engine |
| A. | is self-operating at zero flight speed |
| B. | is not self-operating at zero flight speed |
| C. | requires no air for its operation |
| D. | produces a jet consisting of plasma |
| Answer» C. requires no air for its operation | |
| 230. |
In air breathing jet engine, the jet is formed by expading |
| A. | gases |
| B. | solids |
| C. | liquid |
| D. | highly heated atmospheric air. |
| Answer» E. | |
| 231. |
In the aircraft propellers |
| A. | the propulsive matter is caused to flow around the propelled body |
| B. | propulsive matter is ejected from within the propelled body |
| C. | its functioning does not depend on presence of air |
| D. | all of the above |
| Answer» E. | |
| 232. |
Work ratio of a gas turbine plant is ratio of |
| A. | net work output and work done by turbine |
| B. | net work output and heat supplied |
| C. | work done by turbine and heat supplied |
| D. | work done by turbine and net work output |
| Answer» B. net work output and heat supplied | |
| 233. |
Reheating in gas turbine results in |
| A. | increase of work ratio |
| B. | decrease of thermal efficiency |
| C. | decrease of work ratio |
| D. | both (a) and (b) above |
| Answer» E. | |
| 234. |
The main purpose of reheating in gas turbine is to |
| A. | increase temperature |
| B. | reduce turbine size |
| C. | increase power output |
| D. | increase speed |
| Answer» D. increase speed | |
| 235. |
Gas turbine cycle with regenerator |
| A. | increases thermal efficiency |
| B. | allows high compression ratio |
| C. | decreases heat loss is exhaust |
| D. | allows operation at very high altitudes |
| Answer» B. allows high compression ratio | |
| 236. |
The working fluid in ai turbine is |
| A. | in two phases |
| B. | in three phases |
| C. | in a single phase |
| D. | in the form of air and water mixture |
| Answer» D. in the form of air and water mixture | |
| 237. |
The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turine and fixed higher and lower temperature) with increase in pressure ratio will |
| A. | increase first at fast rate and then slow |
| B. | increase first at slow rate and then fast |
| C. | decrease continuously |
| D. | first increase, reach maximum and then decrease |
| Answer» E. | |
| 238. |
Air-fuel ratio in a jet engine will be of the order of |
| A. | 10: 1 |
| B. | 15: 1 |
| C. | 20 : 1 |
| D. | 60 : 1 |
| Answer» E. | |
| 239. |
High air-fuel ratio is used in gas turbines |
| A. | to increase the output |
| B. | to increase the efficiency |
| C. | to save fuel |
| D. | to reduce the exit temperature |
| Answer» E. | |
| 240. |
The effective power of gas turbines is increased by adding the following in compressor |
| A. | ammonia and water vapour |
| B. | carbon dioxide |
| C. | nitrogen |
| D. | hydrogen |
| Answer» B. carbon dioxide | |
| 241. |
Fighter bombers use following type of engine |
| A. | turbo-jet |
| B. | turbo-propeller |
| C. | rocket |
| D. | ram-jet |
| Answer» B. turbo-propeller | |
| 242. |
In jet engines the products of combustion after passing through the gas lurbine are discharged into |
| A. | atmosphere |
| B. | back to the compressor |
| C. | discharge nozzle |
| D. | vacuum |
| Answer» D. vacuum | |
| 243. |
In jet propulsion power unit, the inlet duct of diverging shape is used in order to |
| A. | collect more air |
| B. | convert kinetic energy of air into pres-sure energy |
| C. | provide robust structure |
| D. | beautify the shape |
| Answer» C. provide robust structure | |
| 244. |
The maximum propulsion efficiency of a turbojet is attained at around following speed - |
| A. | 550 km/hr |
| B. | 1050km/hr |
| C. | 1700 km/hr |
| D. | 2400km /hr |
| Answer» E. | |
| 245. |
Propulsion efficiency of the following order-is obtained in practice |
| A. | 34% |
| B. | 50% |
| C. | 60% |
| D. | 72% |
| Answer» D. 72% | |
| 246. |
In jet engines, paraffin is usually used as the fuel because of its |
| A. | high calorific value |
| B. | ease of atomisation |
| C. | low freezing point |
| D. | (a) and (c) above |
| Answer» E. | |
| 247. |
Propulsive efficiency is defined as ratio of |
| A. | thrust power and fuel energy |
| B. | engine output and propulsive power |
| C. | propulsive power and fuel input |
| D. | thrust power and propulsive power |
| Answer» E. | |
| 248. |
Turbo propeller has the^following additional feature over the turbojet |
| A. | peopeller |
| B. | diffuser |
| C. | intercooler |
| D. | turbine and combustion chamber |
| Answer» B. diffuser | |
| 249. |
A jet engine works on the principle of conservation of |
| A. | mass |
| B. | energy |
| C. | flow |
| D. | linear momentum |
| Answer» E. | |
| 250. |
In the cross compounding of the gas turbine plant |
| A. | h.p. compressor L connected to h.p. turbine and l.p. compressor ot l.p. tur-bine |
| B. | h.p. compressor is connected to l.p. turbine and l.p. compressor is con-nected to h.p. turbine |
| C. | both the arrangements can be employed |
| D. | all are connected in series |
| Answer» C. both the arrangements can be employed | |