MCQOPTIONS
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MCQOPTIONS
This section includes 454 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
_The volume of air delivered in a medium capacity air compressor per unit time is$? |
| A. | 0.1 to 1.2 m³/s |
| B. | 0.15 to 5 m³/s |
| C. | Above 5 m³/s |
| D. | None of these |
| Answer» C. Above 5 m¬¨‚â•/s | |
| 302. |
_Phenomenon of choking in compressor means$? |
| A. | No flow of air |
| B. | Fixed mass flow rate regardless of pressure ratio |
| C. | Reducing mass flow rate with increase in pressure ratio |
| D. | Increased inclination of chord with air steam |
| Answer» C. Reducing mass flow rate with increase in pressure ratio | |
| 303. |
_Ratio of indicated h.p. to shaft h.p. in known as$? |
| A. | Compressor efficiency |
| B. | Isothermal efficiency |
| C. | Volumetric efficiency |
| D. | Mechanical efficiency |
| Answer» E. | |
| 304. |
_The weight per horse power ratio for gas in Turbine as compared to I.C. engine and steam turbine is$? |
| A. | Same |
| B. | Higher |
| C. | Lower |
| D. | None of these |
| Answer» D. None of these | |
| 305. |
_Water is injected in gas turbine cycle to$? |
| A. | Control temperature |
| B. | Control output of turbine |
| C. | Control fire hazards |
| D. | Increase efficiency |
| Answer» C. Control fire hazards | |
| 306. |
_Which of the following plants is smallest and lightest for generating a given amount of power?$? |
| A. | Gas turbine plant |
| B. | Petrol engine |
| C. | Diesel engine |
| D. | Solar plant |
| Answer» B. Petrol engine | |
| 307. |
_The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the$? |
| A. | Adiabatic temperature drop in the stage |
| B. | Total temperature drop |
| C. | Total temperature drop in the stage |
| D. | Total adiabatic temperature drop |
| Answer» D. Total adiabatic temperature drop | |
| 308. |
_Standard air is the air at ________ and relative humidity of 36 percent.$? |
| A. | 0.1 bar and 20°C |
| B. | 1 bar and 20°C |
| C. | 0.1 bar and 40°C |
| D. | 1 bar and 40°C |
| Answer» C. 0.1 bar and 40¬¨‚àûC | |
| 309. |
_The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is$? |
| A. | Heated |
| B. | Compressed air before entering the combustion chamber is heated |
| C. | Bled gas from turbine is heated and readmitted for complete expansion |
| D. | Exhaust gases drive the compressor |
| Answer» C. Bled gas from turbine is heated and readmitted for complete expansion | |
| 310. |
_Separators in compressor installations are located$? |
| A. | Before inter-cooler |
| B. | After inter-cooler |
| C. | After receiver |
| D. | Between after-cooler and air receiver |
| Answer» E. | |
| 311. |
_For minimum work required to compress and deliver a quantity of air by multistage compression$? |
| A. | The compression ratio in each stage should be same |
| B. | The intercooling should be perfect |
| C. | The work-done in each stage should be same |
| D. | All of the above |
| Answer» E. | |
| 312. |
_The ratio of the volume of free air delivery per stroke to the swept volume of the piston, is known as$? |
| A. | Compressor efficiency |
| B. | Volumetric efficiency |
| C. | Isothermal efficiency |
| D. | Mechanical efficiency |
| Answer» C. Isothermal efficiency | |
| 313. |
_In jet propulsion power unit, the inlet duct of diverging shape is used in order to$? |
| A. | Collect more air |
| B. | Convert kinetic energy of air into pressure energy |
| C. | Provide robust structure |
| D. | Beautify the shape |
| Answer» C. Provide robust structure | |
| 314. |
_In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in ________ of the piston.$? |
| A. | One stroke |
| B. | Two strokes |
| C. | Three strokes |
| D. | Four strokes |
| Answer» C. Three strokes | |
| 315. |
_The volumetric efficiency of a compressor$? |
| A. | Increases with decrease in compression ratio |
| B. | Decreases with decrease in compression ratio |
| C. | Increases with increase in compression ratio |
| D. | Decreases with increase in compression ratio |
| Answer» E. | |
| 316. |
_For speed above 3000 km/hour, it is more advantageous to use$? |
| A. | Turbojet engine |
| B. | Ramjet engine |
| C. | Propellers |
| D. | Rockets |
| Answer» C. Propellers | |
| 317. |
Actual compression curve is$? |
| A. | Same as isothermal |
| B. | Same as adiabatic |
| C. | Better than isothermal and adiabatic |
| D. | In between isothermal and adiabatic |
| Answer» E. | |
| 318. |
In the cross compounding of the gas turbine plant$? |
| A. | H.P. compressor is connected to H.P. turbine and L.P. compressor to L.P. turbine |
| B. | H.P. compressor is connected to L.P. turbine and L.P. compressor is connected 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 | |
| 319. |
The criterion of the thermodynamic efficiency for rotary compressor is$? |
| A. | Isentropic compression |
| B. | Isothermal compression |
| C. | Polytropic compression |
| D. | None of the above |
| Answer» B. Isothermal compression | |
| 320. |
Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is$? |
| A. | Higher |
| B. | Lower |
| C. | Equal |
| D. | Can't be compared |
| Answer» C. Equal | |
| 321. |
Inter-cooling in gas turbine results in$? |
| A. | Increase in net output but decrease in thermal efficiency |
| B. | Increase in thermal efficiency but decrease in net output |
| C. | Increase in both thermal efficiency and net output |
| D. | Decrease in both thermal efficiency and net output |
| Answer» B. Increase in thermal efficiency but decrease in net output | |
| 322. |
A compressor at high altitudes will require ________ power.$? |
| A. | Same |
| B. | Less |
| C. | More |
| D. | None of these |
| Answer» C. More | |
| 323. |
Efficiency of gas turbine is increased by$? |
| A. | Reheating |
| B. | Inter cooling |
| C. | Adding a regenerator |
| D. | All of the above |
| Answer» D. All of the above | |
| 324. |
An after-cooler is used to$? |
| A. | Remove impurities from air |
| B. | Reduce volume of air |
| C. | Cause moisture and oil vapour to drop out |
| D. | Cool the air |
| Answer» D. Cool the air | |
| 325. |
A gas turbine used in air craft should have$? |
| A. | High h.p. and low weight |
| B. | Low weight and small frontal area |
| C. | Small frontal area and high h.p. |
| D. | High speed and high h.p. |
| Answer» C. Small frontal area and high h.p. | |
| 326. |
The overall isothermal efficiency of compressor is defined as the ratio of$? |
| A. | Isothermal h.p. to the BHP of motor |
| B. | Isothermal h.p. to adiabatic h.p. |
| C. | Power to drive compressor to isothermal h.p. |
| D. | Work to compress air isothermally to work for actual compression |
| Answer» B. Isothermal h.p. to adiabatic h.p. | |
| 327. |
High air-fuel ratio is used in gas turbines$? |
| A. | To increase the output |
| B. | To increase the efficiency |
| C. | To save fuel |
| D. | To reduce the exit temperature |
| Answer» E. | |
| 328. |
The mass of gas turbine per kW developed is about ________ as that of an I.C. engine.$? |
| A. | Same |
| B. | One-half |
| C. | One fourth |
| D. | One sixth |
| Answer» E. | |
| 329. |
The ratio of work-done per cycle to the stroke volume of the compressor is known as$? |
| A. | Compressor capacity |
| B. | Compression ratio |
| C. | Compressor efficiency |
| D. | Mean effective pressure |
| Answer» E. | |
| 330. |
The assumption made in two stage compression with inter-cooler is that$? |
| A. | There is no pressure drop in the inter-cooler |
| B. | The compression in both the cylinders is polytropic |
| C. | The suction and delivery of air takes place at constant pressure |
| D. | All of the above |
| Answer» E. | |
| 331. |
The compressor efficiency is the$? |
| A. | Isothermal H.P/indicated H.R |
| B. | Isothermal H.P./shaft H.R |
| C. | Total output/air input |
| D. | Compression work/motor input |
| Answer» B. Isothermal H.P./shaft H.R | |
| 332. |
The material commonly used for air craft gas turbine is$? |
| A. | Stainless steel |
| B. | High alloy steel |
| C. | Duralumin |
| D. | Timken, Haste alloys |
| Answer» E. | |
| 333. |
The gas in cooling chamber of a closed cycle gas turbine is cooled at$? |
| A. | Constant volume |
| B. | Constant temperature |
| C. | Constant pressure |
| D. | None of these |
| Answer» D. None of these | |
| 334. |
In a four stage compressor, if the pressure at the first and third stage is 1 bar and 16 bar, then the delivery pressure at the fourth stage will be$? |
| A. | 1 bar |
| B. | 16 bar |
| C. | 64 bar |
| D. | 256 bar |
| Answer» D. 256 bar | |
| 335. |
Diffuser in a compressor is used to$? |
| A. | Increase velocity |
| B. | Make the flow streamline |
| C. | Convert pressure energy into kinetic energy |
| D. | Convert kinetic energy into pressure energy |
| Answer» E. | |
| 336. |
For a two stage reciprocating compressor, compression from p‚ÇÅ to p‚ÇÉ is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the same polytropic process and the atmospheric pressure is pa, then the intermediate pressure p‚ÇÇ is given by$? |
| A. | p‚ÇÇ = (p‚ÇÅ + p‚ÇÉ)/2 |
| B. | p‚ÇÇ = p‚ÇÅ. p‚ÇÉ |
| C. | P‚ÇÇ = Pa √ó p‚ÇÉ/p‚ÇÅ |
| D. | p‚ÇÇ = Pa p‚ÇÉ/p‚ÇÅ |
| Answer» C. P‚Äö√á√á = Pa ‚àö√≥ p‚Äö√á√â/p‚Äö√á√Ö | |
| 337. |
Axial flow compressor resembles$? |
| A. | Centrifugal pump |
| B. | Reciprocating pump |
| C. | Turbine |
| D. | Sliding vane compressor |
| Answer» D. Sliding vane compressor | |
| 338. |
The capacity of a compressor is expressed in$? |
| A. | kg/m² |
| B. | kg/m³ |
| C. | m³/min |
| D. | m³/kg |
| Answer» D. m¬¨‚â•/kg | |
| 339. |
Maximum temperature in a gas turbine is of the order of$? |
| A. | 700°C |
| B. | 2000°C |
| C. | 1500°C |
| D. | 1000°C |
| Answer» B. 2000¬¨‚àûC | |
| 340. |
Separators are generally used in air compressor installations$? |
| A. | Before the inter-cooler |
| B. | After the inter-cooler |
| C. | Between the after-cooler and receiver |
| D. | Before first stage suction |
| Answer» D. Before first stage suction | |
| 341. |
The compression ratio in a gas turbine is of the order of$? |
| A. | 3.5 : 1 |
| B. | 5 : 1 |
| C. | 8 : 1 |
| D. | 12 : 1 |
| Answer» D. 12 : 1 | |
| 342. |
In a single acting reciprocating air compressor, without clearance, the compression of air may be$? |
| A. | Isothermal |
| B. | Polytropic |
| C. | Isentropic |
| D. | Any one of these |
| Answer» E. | |
| 343. |
In a centrifugal compressor, the highest Mach number leading to shock wave in the fluid flow occurs at$? |
| A. | Diffuser inlet radius |
| B. | Diffuser outlet radius |
| C. | Impeller inlet radius |
| D. | Impeller outlet radius |
| Answer» C. Impeller inlet radius | |
| 344. |
A closed cycle gas turbine consists of a$? |
| A. | Compressor |
| B. | Heating chamber |
| C. | Cooling chamber |
| D. | All of these |
| Answer» E. | |
| 345. |
The efficiency and work ratio of a gas turbine plant can be increased by$? |
| A. | Adding heat exchanger |
| B. | Injecting water in/around combustion chamber |
| C. | Reheating the air after partial expansion in the turbine |
| D. | All of the above |
| Answer» E. | |
| 346. |
It is not possible to use closed gas turbine cycle in aeronautical engines because$? |
| A. | It is inefficient |
| B. | It is bulky |
| C. | It requires cooling water for its operation |
| D. | None of the above |
| Answer» D. None of the above | |
| 347. |
A compressor at high altitude will draw$? |
| A. | More power |
| B. | Less power |
| C. | Same power |
| D. | More/less power depending on other factors |
| Answer» C. Same power | |
| 348. |
Which of the following statement is correct relating to rocket engines?$? |
| A. | The combustion chamber in a rocket engine is directly analogous to the reservoir of a supersonic wind tunnel |
| B. | The stagnation conditions exist at the combustion chamber |
| C. | The exit velocities of exhaust gases are much higher than those in jet engine |
| D. | All of the above |
| Answer» E. | |
| 349. |
Fighter bombers use following type of engine$? |
| A. | Turbojet |
| B. | Turbo-propeller |
| C. | Rocket |
| D. | Ramjet |
| Answer» B. Turbo-propeller | |
| 350. |
The work done per unit mass of air in compression will be least when 'n' is equal to$? |
| A. | 1 |
| B. | 1.2 |
| C. | 1.3 |
| D. | 1.4 |
| Answer» B. 1.2 | |