McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 151. |
The air standard efficiency of a Diesel engine depends on |
| A. | Speed |
| B. | Torque |
| C. | Thermodynamic properties of working fluid |
| D. | Cetane value of fuel used |
| E. | Compression ratio |
| Answer» E. Compression ratio | |
| 152. |
The size of a steam engine is 200 x 250 - 300 r.p.m. In this 200 indicates |
| A. | Shaft diameter |
| B. | Steam pressure in 1bs/sq. in. |
| C. | Piston stroke |
| D. | Horse power |
| E. | Cylinder bore |
| Answer» E. Cylinder bore | |
| 153. |
In multistages turbines by introducting reheating |
| A. | Thermal efficiency improves |
| B. | The output of turbine increases |
| C. | Work done by compressor reduces |
| D. | The ratio compressor compressor work/turbine output decreases |
| E. | None of the above |
| Answer» A. Thermal efficiency improves | |
| 154. |
In order to reduce wear and eliminate scuffing, piston ring in internal combustion engines are |
| A. | Made of soft material |
| B. | Provided with grooves |
| C. | Lubricated thoroughly |
| D. | Made of square section |
| E. | Plated with chromium, cadmium or phosphate |
| Answer» E. Plated with chromium, cadmium or phosphate | |
| 155. |
The ends of piston rod in steam engines are connected to |
| A. | Connecting rod and cross-head |
| B. | Crankshaft and cross-head |
| C. | Piston and crankshaft |
| D. | Piston and cross-head |
| E. | Connecting rod and crankshaft |
| Answer» D. Piston and cross-head | |
| 156. |
One horse power-hr is equal to |
| A. | 1 kWh |
| B. | 632 kcal |
| C. | 100,000 kJ |
| D. | 107 Joules |
| E. | None of the above |
| Answer» B. 632 kcal | |
| 157. |
Which of the following boiler uses exhaust of the engine to produce draught? |
| A. | Lamont boiler |
| B. | Cornish boiler |
| C. | Babcock and wilcox boiler |
| D. | Lancashire boiler |
| E. | Locomotive boiler |
| Answer» E. Locomotive boiler | |
| 158. |
In jet engine the compression ratio |
| A. | Varies with altitude |
| B. | Varies with speed |
| C. | Varies as square of speed |
| D. | Remains constant |
| E. | None of the above |
| Answer» C. Varies as square of speed | |
| 159. |
Pour point is the temperature at which oil |
| A. | Starts cracking |
| B. | Will start flowing |
| C. | Barely flows |
| D. | Will ignite |
| E. | Will give off vapours enough for ignition |
| Answer» C. Barely flows | |
| 160. |
Which one of the following factors will not assist in smooth running of a compression ignition engine? |
| A. | Moderate rate of pressure rise |
| B. | Short delay period |
| C. | Minimum of after burning |
| D. | High ignition temperature of fuel |
| E. | None of the above |
| Answer» D. High ignition temperature of fuel | |
| 161. |
In case of an opposed piston engine the combustion chamber |
| A. | Is not provided |
| B. | Is formed between two piston tops |
| C. | Is provided towards crank case side |
| D. | Is fitted outside the cylinder |
| E. | None of the above |
| Answer» B. Is formed between two piston tops | |
| 162. |
Specific heat is |
| A. | The amount of heat required to raise the temperature of a unit quantity of substance through 1?C |
| B. | The amount of heat requred to change the state or condition under which a substance exists without changing its temperature |
| C. | The ratio of quantity of heat required to raise the temperature of a given weight of any substance through 1?C to the quantity of heat required to raise the temperature of same weight of water through 1?C |
| D. | The heat sensed by a mercury thermometer |
| E. | None of the above |
| Answer» C. The ratio of quantity of heat required to raise the temperature of a given weight of any substance through 1?C to the quantity of heat required to raise the temperature of same weight of water through 1?C | |
| 163. |
In a diesel engine the injection pressure is of the order of |
| A. | 1500 kg/cm2 |
| B. | 100 kg/cm2 |
| C. | 1000 kg/cm2 |
| D. | 40 kg/cm2 |
| E. | 500 kg/cm2 |
| Answer» B. 100 kg/cm2 | |
| 164. |
If a water cooled compressor knocks during operation, the probable cause cannot be |
| A. | Loose valve |
| B. | Air filter choked |
| C. | Too much clearance in crank pin |
| D. | Excess cooling in intercooler |
| E. | Loose flywheel or pulley |
| Answer» D. Excess cooling in intercooler | |
| 165. |
Thermal efficiency of a compression ignition engine may be of the order of |
| A. | 35% |
| B. | 50% |
| C. | 20% |
| D. | 75% |
| E. | 70% |
| Answer» A. 35% | |
| 166. |
In centrifugal pumps suction head is |
| A. | Vertical distance from supply level to pump centre line pump being level |
| B. | (A) Above less suction friction heat |
| C. | (A) Above less velocity heat |
| D. | Any of the above |
| E. | None of the above |
| Answer» C. (A) Above less velocity heat | |
| 167. |
Maintenance requirements are least in case of |
| A. | Electric locomotives |
| B. | Carbon dioxide |
| D. | Diesel locomotives |
| E. | Steam locomotives |
| Answer» A. Electric locomotives | |
| 168. |
The higher the temperature required to ignite diesel fuel, |
| A. | Lower the octane number |
| B. | Carbon dioxide |
| C. | Lower the cetane number |
| D. | Higher the cetane number |
| E. | the higher the octane number |
| Answer» C. Lower the cetane number | |
| 169. |
In pumped storage systems, water is pumped |
| A. | Upstream during peak load periods |
| B. | Upstream during off peak periods |
| C. | Upstream during off season |
| D. | None of the above |
| E. | None of the above |
| Answer» B. Upstream during off peak periods | |
| 170. |
The supercharging of diesel engine is done mainly to |
| A. | Cool the engine |
| B. | Increase the life of the engine |
| C. | Increase the power output |
| D. | Increase the speed |
| E. | Reduce the cnoise from the engine |
| Answer» C. Increase the power output | |
| 171. |
In Eicher tractor the engine is |
| A. | Air cooled |
| B. | Horizontal |
| C. | Multi-cylinder type |
| D. | Low compression ratio petrol engine |
| E. | Constant speed engine |
| Answer» A. Air cooled | |
| 172. |
Air fuel ratio in a petrol engine fitted with dirty air cleaner as compared to that with clean air clearance will be |
| A. | Not affected |
| B. | Higher |
| C. | Lower |
| D. | Fluctuating |
| E. | Depends on load |
| Answer» C. Lower | |
| 173. |
Crankshafts are generally |
| A. | Turned from bar stock |
| B. | Die cast |
| C. | Sand cast |
| D. | Forged |
| E. | Cold headed |
| Answer» D. Forged | |
| 174. |
In a condensing steam engine |
| A. | Exhaust steam is condensed in condenser |
| B. | Exhaust steam is not recirculated |
| C. | Steam condenses as soon as it leaves the cylinder |
| D. | Condensed steam is supplied |
| E. | Steam condenses inside cylinder |
| Answer» A. Exhaust steam is condensed in condenser | |
| 175. |
The Apparatus used for the determination of calorific value of solid fuel is |
| A. | Bunsen's apparatus |
| B. | Photo calorimeter |
| C. | Bomb calorimeter |
| D. | Releigh apparatus |
| E. | Osrat's apparatus |
| Answer» C. Bomb calorimeter | |
| 176. |
Stuffing box is provided in |
| A. | Condensing steam engines |
| B. | Non-condensing steam engines |
| C. | High speed steam engines |
| D. | Single acting steam engines |
| E. | Double acting steam engines |
| Answer» E. Double acting steam engines | |
| 177. |
An exciter is a |
| A. | D.C. motor |
| B. | D.C.generator |
| C. | A.C.generator |
| D. | Synchronous motor |
| E. | None of the above |
| Answer» B. D.C.generator | |
| 178. |
An engine operates at 1440 rpm under load whereas no load speed is 1500 rpm. The percentage speed drop of governor will be |
| A. | 2% |
| B. | 3% |
| C. | 4% |
| D. | 10% |
| E. | 6% |
| Answer» C. 4% | |
| 179. |
In a Bomb calorimeter the fuel to be tested is burnt |
| A. | At constant volume |
| B. | At constant pressure |
| C. | There is no consideration of volume or pressure |
| D. | In open atmosphere |
| E. | At constant temperature |
| Answer» A. At constant volume | |
| 180. |
Which fuel will have least air consumption during combustion |
| A. | Spirit |
| B. | Benzol |
| C. | Diesel fuel oil |
| D. | Gasoline |
| E. | Lubricating oil |
| Answer» A. Spirit | |
| 181. |
Movement of air inside engine cylinder does not help in |
| A. | Distribution of fuel |
| B. | Mixing of fuel with air |
| C. | Reduction of after burning |
| D. | Reducing noise |
| E. | None of the above |
| Answer» D. Reducing noise | |
| 182. |
In a Lancashire boiler, the economiser is located |
| A. | Before air preheater |
| B. | After air preheater |
| C. | Between feed pump and boiler |
| D. | At any of the above locations |
| E. | None of the above locations |
| Answer» A. Before air preheater | |
| 183. |
Iso-octane has octane number of |
| A. | 100 |
| B. | 0 |
| C. | 50 |
| D. | 80 to 85 |
| E. | More than 100 |
| Answer» A. 100 | |
| 184. |
Freezing point of petrol is around |
| A. | ?4?C |
| B. | ?30?C |
| C. | 10?C |
| D. | ?13?C |
| E. | 0?C |
| Answer» B. ?30?C | |
| 185. |
1 Torr is equivalent to |
| A. | 1 mm Hg |
| B. | 13.6 cm of water column |
| C. | 760 mm of water |
| D. | 760 mm of Hg |
| E. | None of the above |
| Answer» A. 1 mm Hg | |
| 186. |
The most effective air cleaner for diesel engines is |
| A. | Whirl type |
| B. | Oil bath type |
| C. | Dry type |
| D. | Rope type |
| E. | Wet type |
| Answer» B. Oil bath type | |
| 187. |
An economiser is installed in a boiler plant primarily to |
| A. | Increase steam pressure |
| B. | Increase rate of steam evaporation |
| C. | Superheat the steam |
| D. | Purify boiler feed water |
| E. | Reduce fuel consumption |
| Answer» E. Reduce fuel consumption | |
| 188. |
The equilibrium conditions between supersaurated vapour and a cooled liquid surface are expressed in |
| A. | Dalton's equation |
| B. | Napier's equation |
| C. | Kelvin Helmhotz equation |
| D. | Clapcyron's equation |
| E. | Calender's equation |
| Answer» C. Kelvin Helmhotz equation | |
| 189. |
Most of the heat generated in I.C. engines is transferred to surrounding medium by |
| A. | Conduction only |
| B. | Convection only |
| C. | Conduction and convection |
| D. | Radiation only |
| E. | None of the above |
| Answer» C. Conduction and convection | |
| 190. |
Vapour lock is |
| A. | Supply of liquid fuel particles to engine in maixture |
| B. | Excess fuel supply to engine due to faster evaporation |
| C. | Complete or partial stoppage of fuel supply due to vaporisation of fuel in supply steam |
| D. | Lock of vaporization of fuel to atomspheric pressure |
| E. | Locking carburettor jets due to vapour pressure |
| Answer» C. Complete or partial stoppage of fuel supply due to vaporisation of fuel in supply steam | |
| 191. |
The steam pressure in a pass out turbine may be expected to be in the range |
| A. | 10 kg/cm2 to 20 kg/cm2 |
| B. | 100 kg/cm2 to 150 kg/cm2 |
| C. | 150 kg/cm2 to 300 kg/cm2 |
| D. | 75 kg/cm2 to 100 kg/cm2 |
| E. | 40 kg/cm2 to 75 kg/cm2 |
| Answer» A. 10 kg/cm2 to 20 kg/cm2 | |
| 192. |
A regenerator in a gas turbine |
| A. | Reduces heat loss in exhaust |
| B. | permits use of higher compression ratio |
| C. | Improves thermal efficiency |
| D. | Permits use of fuels of inferior quality |
| E. | None of the above |
| Answer» C. Improves thermal efficiency | |
| 193. |
Higher proportion of residual gases in the cylinder would mean |
| A. | Higher volumetric efficiency |
| B. | Lower volumetric efficiency |
| C. | No change in volumetric efficiency |
| D. | Depends on other factors |
| E. | None of the above |
| Answer» B. Lower volumetric efficiency | |
| 194. |
Low grade fuels have |
| A. | Low moisture content |
| B. | Low ash content |
| C. | Low calorific valve |
| D. | Low carbon content |
| E. | None of the above |
| Answer» C. Low calorific valve | |
| 195. |
A gas turbine cycle with regenerator has a thermal efficiency of 26%. If intercooler and reheater are also introduced what could be expected thermal efficiency |
| A. | 50% |
| B. | 10% |
| C. | 60% |
| D. | 40% |
| E. | 30% |
| Answer» E. 30% | |
| 196. |
Free piston engines find application in |
| A. | Compressed air supply |
| B. | Mining installations |
| C. | Gas turbines |
| D. | Supercharging of diesel engines |
| E. | None of the above |
| Answer» C. Gas turbines | |
| 197. |
In case of supersonic flow through the nozzle, when the cross-section increases in the direction of flow |
| A. | The velocity will decrease in the direction of flow |
| B. | The pressure will increase in the direction of flow |
| C. | The velocity will increase while the pressure will decrease in the direction of flow |
| D. | The velocity will decrease while the pressure will increase in the direction of flow |
| E. | None of the above |
| Answer» C. The velocity will increase while the pressure will decrease in the direction of flow | |
| 198. |
The performance of air compressor at high altitudes as compared to that at sea level will be |
| A. | Will depend upon temperature of air |
| B. | Will depend on type of compressor |
| C. | Better |
| D. | Same |
| E. | Inferior |
| Answer» E. Inferior | |
| 199. |
To avoid moisture trubles, the branch connection from compressed air line are taken from |
| A. | Top side |
| B. | Bottom side |
| C. | Left side |
| D. | Any side |
| E. | Right side |
| Answer» A. Top side | |
| 200. |
Which turbine has identical fixed and moving blades |
| A. | Carbon dioxide |
| B. | De Laval turbine |
| C. | Parson's reaction turbine |
| D. | Rateau's turbine |
| E. | Hero's turbine |
| Answer» C. Parson's reaction turbine | |
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