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.
| 151. |
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 | |
| 152. |
Volumetric efficiency of a compressor without clearance volume%! |
| A. | Increases with increase in compression ratio |
| B. | Decreases with increase in compression ratio |
| C. | Is not dependent upon compression ratio |
| D. | May increase/decrease depending on compressor capacity |
| Answer» D. May increase/decrease depending on compressor capacity | |
| 153. |
The work ratio of simple gas turbine cycle depends on%! |
| A. | Pressure ratio |
| B. | Maximum cycle temperature |
| C. | Minimum cycle temperature |
| D. | All of the above |
| Answer» E. | |
| 154. |
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 m¬¨‚â•/ mt. | |
| 155. |
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 | |
| 156. |
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 | |
| 157. |
The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is%! |
| A. | Pressure drop across the valves |
| B. | Superheating in compressor |
| C. | Clearance volume and leakages |
| D. | All of these |
| Answer» E. | |
| 158. |
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 | |
| 159. |
Gas turbine blades are given a rake%! |
| A. | Equal to zero |
| B. | In the direction of motion of blades |
| C. | Opposite to the direction of motion of blades |
| D. | Depending on the velocity |
| Answer» C. Opposite to the direction of motion of blades | |
| 160. |
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 | |
| 161. |
*$_The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is? |
| A. | Pressure drop across the valves |
| B. | Superheating in compressor |
| C. | Clearance volume and leakages |
| D. | All of these |
| Answer» E. | |
| 162. |
*$_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 | |
| 163. |
*$_The type of rotary compressor used in aeroplanes, is of? |
| A. | Centrifugal type |
| B. | Axial flow type |
| C. | Radial flow type |
| D. | None of these |
| Answer» C. Radial flow type | |
| 164. |
*$_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 | |
| 165. |
*$_Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm. The air pressure will be? |
| A. | 1.03 kg/cm² |
| B. | 1.06 kg/cm² |
| C. | 1.00 kg/cm² |
| D. | 0.53 kg/cm² |
| Answer» D. 0.53 kg/cm¬¨‚⧠| |
| 166. |
*$_The work ratio of simple gas turbine cycle depends on? |
| A. | Pressure ratio |
| B. | Maximum cycle temperature |
| C. | Minimum cycle temperature |
| D. | All of the above |
| Answer» E. | |
| 167. |
*$_The output of a gas turbine is 300 KW and its efficiency is 20 percent, the heat supplied is? |
| A. | 6000 KW |
| B. | 15 KW |
| C. | 600 KW |
| D. | 150 KW |
| Answer» C. 600 KW | |
| 168. |
*$_A centrifugal compressor works on the principle of? |
| A. | Conversion of pressure energy into kinetic energy |
| B. | Conversion of kinetic energy into pressure energy |
| C. | Centripetal action |
| D. | Generating pressure directly |
| Answer» C. Centripetal action | |
| 169. |
*$_A closed cycle gas turbine works on? |
| A. | Carnot cycle |
| B. | Rankine cycle |
| C. | Ericsson cycle |
| D. | Joule cycle |
| Answer» E. | |
| 170. |
*$_Gas turbine blades are given a rake? |
| A. | Equal to zero |
| B. | In the direction of motion of blades |
| C. | Opposite to the direction of motion of blades |
| D. | Depending on the velocity |
| Answer» C. Opposite to the direction of motion of blades | |
| 171. |
*$_To avoid moisture troubles, the branch connections from compressed air lines should be taken from? |
| A. | Top side of main |
| B. | Bottom side of main |
| C. | Left side of main |
| D. | Right side of main |
| Answer» B. Bottom side of main | |
| 172. |
*$_Surging is the phenomenon of? |
| A. | Air stream blocking the passage |
| B. | Motion of air at sonic velocity |
| C. | Unsteady, periodic and reversed flow |
| D. | Air stream not able to follow the blade contour |
| Answer» D. Air stream not able to follow the blade contour | |
| 173. |
*$_The maximum combustion pressure in gas turbine as compared to I.C. engine is? |
| A. | More |
| B. | Less |
| C. | Same |
| D. | Depends on other factors |
| Answer» C. Same | |
| 174. |
*$_Which is false statement about advantages of multistage compressor in comparison to single stage compressor?? |
| A. | Less power requirement |
| B. | Better mechanical balance |
| C. | Less loss of air due to leakage past the cylinder |
| D. | Lower volumetric efficiency |
| Answer» E. | |
| 175. |
*$_In a centrifugal compressor, an increase in speed at a given pressure ratio causes? |
| A. | Increase in flow |
| B. | Decrease in flow |
| C. | Increase in efficiency |
| D. | Increase in flow and decrease in efficiency |
| Answer» E. | |
| 176. |
*$_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 | |
| 177. |
*$_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 m¬¨‚â•/ mt. | |
| 178. |
*/*_A closed cycle gas turbine gives ________ efficiency as compared to an open cycle gas turbine.? |
| A. | Same |
| B. | Lower |
| C. | Higher |
| D. | None of these |
| Answer» D. None of these | |
| 179. |
*/*_Mining industry usually employs following motive power? |
| A. | A.C. electric motor |
| B. | Compressed air |
| C. | Petrol engine |
| D. | Diesel engine |
| Answer» C. Petrol engine | |
| 180. |
*/*_The volume of air delivered by the compressor is called? |
| A. | Free air delivery |
| B. | Compressor capacity |
| C. | Swept volume |
| D. | None of these |
| Answer» C. Swept volume | |
| 181. |
*/*_1 m of air at atmospheric condition weighs approximately? |
| A. | 0.5 kg |
| B. | 1.0 kg |
| C. | 1.3 kg |
| D. | 2.2 kg |
| Answer» D. 2.2 kg | |
| 182. |
*/*_Water gas is produced by? |
| A. | Carbonisation of coal |
| B. | Passing steam over incandescent coke |
| C. | Passing air and a large amount of steam over waste coal at about 65°C |
| D. | Partial combustion of coal, eke, anthracite coal or charcoal in a mixed air steam blast |
| Answer» C. Passing air and a large amount of steam over waste coal at about 65¬¨‚àûC | |
| 183. |
*/*_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 | |
| 184. |
*/*_Reheating in multistage expansion gas turbine results in? |
| A. | High thermal efficiency |
| B. | Reduction in compressor work |
| C. | Decrease of heat loss in exhaust |
| D. | Maximum work output |
| Answer» E. | |
| 185. |
*/*_In jet engines the products of combustion after passing through the gas turbine are discharged into? |
| A. | Atmosphere |
| B. | Back to the compressor |
| C. | Discharge nozzle |
| D. | Vacuum |
| Answer» D. Vacuum | |
| 186. |
*/*_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. | |
| 187. |
*/*_The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation? |
| A. | 0.1% |
| B. | 0.5% |
| C. | 1.0% |
| D. | 5% |
| Answer» D. 5% | |
| 188. |
*/*_Choose the correct statement? |
| A. | Gas turbine requires lot of cooling water |
| B. | Gas turbine is capable of rapid start up and loading |
| C. | Gas turbines has flat efficiency at part loads |
| D. | Gas turbines have high standby losses and require lot of maintenance |
| Answer» C. Gas turbines has flat efficiency at part loads | |
| 189. |
*/*_In gas turbines, high thermal efficiency is obtained in? |
| A. | Closed cycle |
| B. | Open cycle |
| C. | Both of the above |
| D. | Closed/open depending on other considerations |
| Answer» B. Open cycle | |
| 190. |
*/*_The maximum propulsion efficiency of a turbojet is attained at around following speed? |
| A. | 550 km/hr |
| B. | 1050 km/hr |
| C. | 1700 km/hr |
| D. | 2400 km/hr |
| Answer» E. | |
| 191. |
*/*_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 | |
| 192. |
*/*_A compressor mostly used for supercharging of I.C. engines is? |
| A. | Radial flow compressor |
| B. | Axial flow compressor |
| C. | Roots blower |
| D. | Reciprocating compressor |
| Answer» B. Axial flow compressor | |
| 193. |
*/*_The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turbine 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. | |
| 194. |
*/*_When the outlet angle from the rotor of a centrifugal compressor is more than 90°, then the blades are said to be? |
| A. | Forward curved |
| B. | Backward curved |
| C. | Radial |
| D. | None of these |
| Answer» B. Backward curved | |
| 195. |
*/*_In air compressors, free air delivery means 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» B. Volume of air delivered by the compressor | |
| 196. |
*/*_Intercooling in gas turbines? |
| A. | Decreases net output but increases thermal efficiency |
| B. | Increases net output but decreases thermal efficiency |
| C. | Decreases net output and thermal efficiency both |
| D. | Increases net output and thermal efficiency both |
| Answer» E. | |
| 197. |
*/*_Gas turbine as compared to internal combustion engine? |
| A. | Can be driven at a very high speed |
| B. | Produces uniform torque |
| C. | Has more efficiency |
| D. | All of these |
| Answer» E. | |
| 198. |
*/*_Rotary compressor is best suited for? |
| A. | Large quantity of air at high pressure |
| B. | Small quantity of air at high pressure |
| C. | Small quantity of air at low pressure |
| D. | Large quantity of air at low pressure |
| Answer» C. Small quantity of air at low pressure | |
| 199. |
*/*_The ratio of the indicated power to the shaft power or brake power of the motor or engine required to drive the compressor, is called? |
| A. | Compressor efficiency |
| B. | Volumetric efficiency |
| C. | Isothermal efficiency |
| D. | Mechanical efficiency |
| Answer» E. | |
| 200. |
*/*_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. | |