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MCQOPTIONS
This section includes 4791 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 4301. |
In an axial flow compressor, the ratio of pressure in theTOtor blades to the pressure rise in the compressor in one stage is known as |
| A. | work factor |
| B. | slip factor |
| C. | degree of reaction |
| D. | pressure coefficient |
| Answer» D. pressure coefficient | |
| 4302. |
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 | |
| 4303. |
The free air delivery is the volume of air that can be delivered by a compressor freely. |
| A. | True |
| B. | False |
| Answer» C. | |
| 4304. |
The ratio of the discharge pressure to the inlet pressure of air is called |
| A. | compression ratio |
| B. | expansion ratio |
| C. | compressor efficiency |
| D. | volumetric efficiency |
| Answer» B. expansion ratio | |
| 4305. |
In a jet engine, the air-fuel ratio is |
| A. | 30:1 |
| B. | 40:1 |
| C. | 50:1 |
| D. | 60:1 |
| Answer» E. | |
| 4306. |
A regenerator in a gas turbine improves thermal efficiency. |
| A. | Correct |
| B. | Incorrect |
| Answer» B. Incorrect | |
| 4307. |
The velocity of air entering in a rocket is __________ as compared to an aircraft. |
| A. | zero |
| B. | less |
| C. | more |
| D. | same |
| Answer» B. less | |
| 4308. |
The multi-stage compression ofair as compared to single stage compression |
| A. | improves volumetric efficiency for the given pressure ratio |
| B. | reduces workdone per kg of air |
| C. | gives more uniform torque |
| D. | all of these |
| Answer» E. | |
| 4309. |
Which one of the following is the effect of blade shape on performance of a centrifugal compressor ? |
| A. | Backward curved blades has poor efficiency |
| B. | Backward curved blades lead to stable performance |
| C. | Forward curved blades has higher efficiency |
| D. | Forward curved blades produce lower pressure ratio |
| Answer» E. | |
| 4310. |
Which of the following bladings will give maximum pressure rise in a centrifugal compressor, assuming the same overall dimensions, blade inlet angle and rotational speeds ? |
| A. | Forward curved blades |
| B. | Backward curved blades |
| C. | Radial blades |
| D. | all of these |
| Answer» B. Backward curved blades | |
| 4311. |
In a centrifugal compressor, the air enters the impeller axially and leaves the vane radially. |
| A. | Yes |
| B. | No |
| Answer» C. | |
| 4312. |
The mass of gas turbine per kW developed is about __________ as that of an I.C. engine. |
| A. | same |
| B. | one-half |
| C. | one-fourth |
| D. | one-sixth |
| Answer» E. | |
| 4313. |
The propulsive power of the rocket is (where v1 = Jet velocity, and v2 = Air-craft velocity) |
| A. | <img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/378-148-1.png"> |
| B. | <img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/378-148-2.png"> |
| C. | <img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/378-148-3.png"> |
| D. | <img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/378-148-4.png"> |
| Answer» B. <img src="/_files/images/mechanical-engineering/compressors-gas-dynamics-and-gas-turbines/378-148-2.png"> | |
| 4314. |
In gas turbines, the work input with intercooling is __________ the work input with no intercooling. |
| A. | less man |
| B. | more than |
| Answer» B. more than | |
| 4315. |
Maximum work is saved in a two stage reciprocating air compressor with incomplete intercooling. |
| A. | Agree |
| B. | Disagree |
| Answer» C. | |
| 4316. |
In a centrifugal compressor, the ratio of the __________ to the blade velocity is called slip factor. |
| A. | inlet whirl velocity |
| B. | outlet whirl velocity |
| C. | inlet velocity of flow |
| D. | outlet velocity of flow |
| Answer» E. | |
| 4317. |
In a turbo jet engine, subsequent to heat addition to compressed air, to get the power output, the working substance is expanded in |
| A. | exit nozzle, which is a constant volume process |
| B. | exit nozzle, which is essentially an isentropic process |
| C. | turbine blades, which is a constant volume process |
| D. | turbine blades, which is essentially an isentropic process |
| Answer» E. | |
| 4318. |
The air is delivered __________ in one revolution in case of a three-lobbed rotor. |
| A. | two times |
| B. | three times |
| C. | four times |
| D. | six times |
| Answer» E. | |
| 4319. |
A compressor at high altitudes will require __________ power. |
| A. | same |
| B. | less |
| C. | more |
| Answer» C. more | |
| 4320. |
The mean effective pressure of the compressor is the |
| A. | actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions |
| B. | volume of air delivered by the compressor |
| C. | volume of air sucked by the compressor during its suction stroke |
| D. | none of the above |
| Answer» E. | |
| 4321. |
The compressor capacity will be __________ if the temperature of intake air is lowest. |
| A. | lowest |
| B. | highest |
| Answer» C. | |
| 4322. |
Reheating in a multi-stage expansion gas turbine __________ compressor work. |
| A. | has no effect on |
| B. | decreases |
| C. | increases |
| Answer» C. increases | |
| 4323. |
A machine used to raise the pressure of air is called |
| A. | gas turbine |
| B. | I.C engine |
| C. | compressor |
| D. | air motor |
| Answer» D. air motor | |
| 4324. |
The overall efficiency of the compressed air system is the |
| A. | ratio of shaft output of the air motor to the shaft input to the compressor |
| B. | ratio of shaft input to the compressor to the shaft output of air motor |
| C. | product of shaft output of air motor and shaft input to the compressor |
| D. | none of the above |
| Answer» B. ratio of shaft input to the compressor to the shaft output of air motor | |
| 4325. |
In a jet engine, the compression varies as the square of the speed. |
| A. | Correct |
| B. | Incorrect |
| Answer» B. Incorrect | |
| 4326. |
In a single acting reciprocating air compressor, without clearance, the compression of air may be |
| A. | isothermal |
| B. | polytropic |
| C. | isentropic |
| D. | any one of these |
| Answer» E. | |
| 4327. |
For minimum work in multi-stage compression, the workdone on all stages should be equal. |
| A. | Yes |
| B. | No |
| Answer» B. No | |
| 4328. |
The thrust of a jet propulsion power unit can be increased by |
| A. | injecting water into the compressor |
| B. | burning fuel after gas turbine |
| C. | injecting ammonia into the combustion chamber |
| D. | all of the above |
| Answer» E. | |
| 4329. |
Reheating in a gas turbine |
| A. | increases the thermal efficiency |
| B. | increases the compressor work |
| C. | increases the turbine work |
| D. | decreases the thermal efficiency |
| Answer» B. increases the compressor work | |
| 4330. |
In a single stage, single acting reciprocating air compressor, without clearance, the workdone on the air during isentropic compression is __________ the heat required to raise the temperature of air from T1 to T2 at a constant pressure. |
| A. | equal to |
| B. | less than |
| C. | greater than |
| Answer» B. less than | |
| 4331. |
In a compressor, work is done on the piston during suction of air and work is done by the piston during compression as well as delivery of air. |
| A. | Agree |
| B. | Disagree |
| Answer» B. Disagree | |
| 4332. |
Workdone by an air compressor __________ upon the way in which the air is compressed. |
| A. | depends |
| B. | does not depend |
| Answer» B. does not depend | |
| 4333. |
The scavenging efficiency of a four stroke cycle diesel engine is |
| A. | below 50% |
| B. | between 50 and 85% |
| C. | between 85 and 95% |
| D. | between 95 and 100% |
| Answer» E. | |
| 4334. |
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 | |
| 4335. |
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 | |
| 4336. |
A moderator |
| A. | absorbs neutrons |
| B. | does not absorb neutrons |
| C. | accelerates neutrons |
| D. | none of these |
| Answer» C. accelerates neutrons | |
| 4337. |
The thermodynamic cycle on which the petrol engine works, is |
| A. | Otto cycle |
| B. | Joule cycle |
| C. | Rankine cycle |
| D. | Stirling cycle |
| Answer» B. Joule cycle | |
| 4338. |
For the same maximum pressure and heat input, the exhaust temperature of petrol engine is __________ than that of diesel engine. |
| A. | less |
| B. | more |
| Answer» C. | |
| 4339. |
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 |
| Answer» B. Disagree | |
| 4340. |
In a four stroke cycle diesel engine, the exhaust valve |
| A. | opens at 30 before bottom dead cnetre and closes at 10 after top dead centre |
| B. | opens at 30 after bottom dead centre and closes at 10 before top dead centre |
| C. | opens at bottom dead centre and closes at top dead centre |
| D. | may open and close anywhere |
| Answer» B. opens at 30 after bottom dead centre and closes at 10 before top dead centre | |
| 4341. |
The two stroke cycle engines have lighter flywheel. |
| A. | Agree |
| B. | Disagree |
| Answer» B. Disagree | |
| 4342. |
The advancing of spark timing in spark ignition engines will __________ knocking tendency. |
| A. | increase |
| B. | reduce |
| C. | not effect |
| Answer» B. reduce | |
| 4343. |
The knocking in spark ignition engines can be reduced by |
| A. | retarding the spark |
| B. | increasing the engine speed |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» D. none of these | |
| 4344. |
An atom bomb utilises uncontrolled nuclear fission. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 4345. |
The ratio of the brake power to the indicated power is called |
| A. | mechanical efficiency |
| B. | overall efficiency |
| C. | indicated thermal efficiency |
| D. | volumetric efficiency |
| Answer» B. overall efficiency | |
| 4346. |
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 | |
| 4347. |
A mixture containing 65% of iso-octane and 35% of normal heptane will have |
| A. | cetane number 65 |
| B. | octane number 65 |
| C. | qetane number 35 |
| D. | octane number 35 |
| Answer» C. qetane number 35 | |
| 4348. |
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 | |
| 4349. |
Which of the following does not relate to a compression ignition engine? |
| A. | Fuel pump |
| B. | Fuel injector |
| C. | Governor |
| D. | Carburettor |
| Answer» E. | |
| 4350. |
The control rods in the control system of nuclear reactors are used to |
| A. | absorb excess neutrons |
| B. | control fuel consumption |
| C. | control temperature |
| D. | all of these |
| Answer» B. control fuel consumption | |