McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 1. |
Octane number of petrol generally available is in the range |
| A. | 10 to 25 |
| B. | 55 to 65 |
| C. | 25 to 60 |
| D. | 20 to 75 |
| E. | 80 to 100 |
| Answer» E. 80 to 100 | |
| 2. |
In spark ignition engines, the knocking tendency is reduced by |
| A. | Reduction of compression ratio |
| B. | Advancing ignition timing |
| C. | Increasing exhaust temperature |
| D. | Adding dope like tetra ethy lead to the fuel |
| E. | All of the above |
| Answer» D. Adding dope like tetra ethy lead to the fuel | |
| 3. |
In thermodynamic analysis, a pure substance is that which |
| A. | consists of only a single chemical species |
| B. | May have a number of chemical species that the composition remains constant |
| C. | has no dissolved impurities |
| D. | behaves as perfect gas |
| E. | None of the above |
| Answer» B. May have a number of chemical species that the composition remains constant | |
| 4. |
Leaking radiator tubes are generally |
| A. | Soldered |
| B. | Welded |
| C. | Left unattended |
| D. | Brazed |
| E. | Replaced |
| Answer» A. Soldered | |
| 5. |
When steam expands without doing mechanical work, its enthalpy |
| A. | Increases |
| B. | Decreases |
| C. | Does not change |
| D. | Depends on the factors |
| E. | None of the above |
| Answer» C. Does not change | |
| 6. |
Generally steam turbines in power station operate at |
| A. | 1000 RPM |
| B. | 3000 RPM |
| C. | 375 RPM |
| D. | 50 RPM |
| E. | 1500 RPM |
| Answer» B. 3000 RPM | |
| 7. |
Thermionic converters are based on |
| A. | Seebeck effect |
| B. | Microwave theory |
| C. | Energy contained in thermal conductors |
| D. | Transfer of electrons |
| E. | None of the above |
| Answer» D. Transfer of electrons | |
| 8. |
Anthydrous substance is |
| A. | Dry substance |
| B. | Free of hydrogen |
| C. | Free of humidity |
| D. | Crystalline substance |
| E. | Free of water specially water of crystallization |
| Answer» E. Free of water specially water of crystallization | |
| 9. |
Fuel which detonates easily is |
| A. | Toulene |
| B. | Alcohol |
| C. | Iso-octane |
| D. | n-Heptane |
| E. | Benzene |
| Answer» D. n-Heptane | |
| 10. |
In compression ignition engine fuel ignition accelerators are added to |
| A. | Reduce combustion knock |
| B. | Accelerate combustion knock |
| C. | Reduce combustion chamber temp |
| D. | Increase delay period |
| E. | None of the above |
| Answer» A. Reduce combustion knock | |
| 11. |
Working pressure of a boiler does not depend upon |
| A. | Factor of safety |
| B. | Tensile strength of shell |
| C. | Thickness of shell |
| D. | Efficiency of joint |
| E. | Type of fuel being fired |
| Answer» E. Type of fuel being fired | |
| 12. |
Oil rings are slotted to |
| A. | Remove oil from cylinder |
| B. | Minimise friction |
| C. | Reduce the bulk |
| D. | Better lubrication of cylinder walls |
| E. | Provide an escape for the oil that the slot edges cut from the cylinder wall |
| Answer» E. Provide an escape for the oil that the slot edges cut from the cylinder wall | |
| 13. |
A gas turbine cycle operates through pressures ratio of 5. Air enters the compressor at atmospheric pressure and 25?C and entry to the turbine is at 800?C. The thermal efficiency of the plant has been found to be 37%. Now, if compressor and turbine efficiencies of 80% are taken into account, the value, of thermal efficiency will be |
| A. | 37% |
| B. | 40% |
| C. | 38.50% |
| D. | 17.75% |
| E. | 45% |
| Answer» D. 17.75% | |
| 14. |
The chemical usually added for increasing the knock resistance of a petrol engine is |
| A. | Tetra-ethy lead |
| B. | n-heptane |
| C. | Pyro gallic acid |
| D. | Methyl alcohol |
| E. | Benzol |
| Answer» A. Tetra-ethy lead | |
| 15. |
Pure cetane |
| A. | Has cetane number of 0 |
| B. | Promotes detonation |
| C. | Is a straight chain paraffin |
| D. | Has cetane number of 100 |
| E. | Is a blue coloured liquid |
| Answer» C. Is a straight chain paraffin | |
| 16. |
In aircraft using gas turbine the cycle used is |
| A. | Reheating |
| B. | Regeneration |
| C. | Reheating with regeneration |
| D. | Simple |
| E. | Multi-stage expansion with reheating and regeneration |
| Answer» D. Simple | |
| 17. |
Which of the following automobile is relatively free from pollution problems |
| A. | Diesel engine powered |
| B. | Wankel engine powered |
| C. | Batterly powered |
| D. | Gas turbine powered |
| E. | Petrol engine powered |
| Answer» C. Batterly powered | |
| 18. |
During idling a petrol engine requires |
| A. | Rich mixture |
| B. | None of above |
| C. | Chemically correct mixture |
| D. | Variable mixture |
| E. | Lean mixture |
| Answer» A. Rich mixture | |
| 19. |
A diesel engine is to be redesigned to improve the overload capacity. The design feature which will be influenced is |
| A. | Size of fuel injection equipment |
| B. | Lubrication |
| C. | Air capacity of cylinder |
| D. | Cooling water velocity |
| E. | All of the above |
| Answer» E. All of the above | |
| 20. |
Which of the following pollutants result from automobile exhaust? |
| A. | Carbon monoxide |
| B. | Nitrous oxide |
| C. | Hydro carbons |
| D. | Sulphur dioxide |
| E. | All of the above |
| Answer» E. All of the above | |
| 21. |
Which is incorrect? |
| A. | Compression ratio = initial volume + final volume |
| B. | Final pressure = Initial pressure x compression ratio |
| C. | Initial pressure = final pressure + compression ratio |
| D. | Initial volume = compression ratio x final volume |
| E. | None of the above |
| Answer» E. None of the above | |
| 22. |
Coking is |
| A. | Formation of lumps or masses of coke in boiler furnaces at high temperatures |
| B. | Heating of coal in absence of air driving carbon and leaving behind the residue of carbon |
| C. | Burning of coal in a furnace |
| D. | Producing lumps of coal from fine powders with the help of a binder |
| E. | None of the above |
| Answer» B. Heating of coal in absence of air driving carbon and leaving behind the residue of carbon | |
| 23. |
In a diesel engine the inlet pressure is more than the atmospheric pressure. Therefore; it can be concluded that |
| A. | The engine is high speed type |
| B. | The engine is air cooled |
| C. | The engine is water cooled |
| D. | The engine is slow speed type |
| E. | The engine is supercharged |
| Answer» E. The engine is supercharged | |
| 24. |
In a impulse turbine while steam flows through the moving blades |
| A. | Velocity increases |
| B. | Velocity reduces |
| C. | Both velocity as well as pressure increase |
| D. | Velocity reduces while pressure increases |
| E. | Pressure reduces |
| Answer» B. Velocity reduces | |
| 25. |
A hydrograph is a plot of discharge through a river versus |
| A. | Time |
| B. | Velocity of water |
| C. | Rate of flow of water |
| D. | None of the above |
| E. | None of the above |
| Answer» A. Time | |
| 26. |
A gas used in gas engine trial was tested in a Boys Calorimeter. The pressure of gas supply was 7 cm of water column. If the barometric pressure is 760 mm of mercury, the absolute pressure of the gas would be |
| A. | 0.007 kg/sq-cm |
| B. | 0.14 kg/sq-cm |
| C. | 1.04 kg/sq-cm |
| D. | 1.14 kg/sq-cm |
| E. | None of the above |
| Answer» C. 1.04 kg/sq-cm | |
| 27. |
A cross-head has |
| A. | Reciprocating motion |
| B. | Rotory motion |
| C. | Oscillating motion |
| D. | (A) and (B) only |
| E. | (A) and (C) only |
| Answer» A. Reciprocating motion | |
| 28. |
An average percentage of Carbon and Hydrogen in Petrol may be roughly given as |
| A. | 70% C, 70% H2 |
| B. | 15% C, 85% H2 |
| C. | 50% C, 50% H2 |
| D. | 85% C, 150% H2 |
| E. | 60% C, 40% H2 |
| Answer» D. 85% C, 150% H2 | |
| 29. |
The overload capacity of diesel engine is usually around |
| A. | 50% |
| B. | Carbon dioxide |
| C. | 1% |
| D. | 25% |
| E. | 10% |
| Answer» E. 10% | |
| 30. |
A gas turbine plant operates between 1 ata and 9 ata with minimum and maximum cycle temperature of 25?C and 1000?C. A two stage compressor is provided with perfect intercooling and work is equally divided between the two stages. The intermediate pressure will be |
| A. | 5.5 ata |
| B. | 3 ata |
| C. | 4 ata |
| D. | 7.5 ata |
| E. | 5 ata |
| Answer» B. 3 ata | |
| 31. |
In cse the exhaust silencer of a petrol engine is partly choked, it is likely to result in |
| A. | Increased compression ratio |
| B. | Increased fuel consumption |
| C. | Reduced fuel consumption |
| D. | Reduced compression ratio |
| E. | None of the above |
| Answer» B. Increased fuel consumption | |
| 32. |
Which of the following engine uses two fuel simultaneously? |
| A. | Multi-fuel engine |
| B. | Duel fuel engine |
| C. | Wankle engine |
| D. | Free piston gas generator |
| E. | All of the above |
| Answer» B. Duel fuel engine | |
| 33. |
Which of the following constituent of air has the least proportion? |
| A. | Carbon monoxide |
| B. | Xenon |
| C. | Argon |
| D. | Helium |
| E. | Neon |
| Answer» B. Xenon | |
| 34. |
Which of the following is a false statement. A multicylinder diesel engine is missing on one or more cylinders. The cause may be |
| A. | Valve sticky |
| B. | Insufficient fuel supply to cylinders |
| C. | Compression poor |
| D. | Air cleaner plugged |
| E. | Valves leaky |
| Answer» D. Air cleaner plugged | |
| 35. |
If a steam injector lifts the water but fails to force it into the boiler, the trouble may not be due to |
| A. | Combining tube clogged |
| B. | Insufficient steam pressure |
| C. | Sry steam |
| D. | Leake in water pipe |
| E. | Any of the above |
| Answer» C. Sry steam | |
| 36. |
Which one of the following symptoms will not show that combustion is becessary complete. |
| A. | Presence of free carbon in exhaust |
| B. | Presence of carbon monoxide in exhaust |
| C. | Presence of oxygen in exhaust |
| D. | Presence of nitrogen in exhaust |
| E. | All of the above |
| Answer» D. Presence of nitrogen in exhaust | |
| 37. |
Presence of impurities in ice |
| A. | Does not have any effect |
| B. | Lowers melting point |
| C. | Makes it heavier than water |
| D. | Raises melting point |
| E. | Depends on other factors |
| Answer» B. Lowers melting point | |
| 38. |
Piston rod is provided in |
| A. | Slow speed steam engines |
| B. | Double acting steam engines |
| C. | High speed steam engines |
| D. | Non-condensing steam engines |
| E. | Condensing steam engines |
| Answer» B. Double acting steam engines | |
| 39. |
The pressure of steam generated in a boiler as recorded by the Bourdon pressure gauge was 2.2 kg/sq-cm. If the barometer reads 774 mm of mercury the absolute pressure of steam would be |
| A. | 0.2 kg/sq-cm |
| B. | 9.774 kg/sq-cm |
| C. | 1.025 kg/sq-cm |
| D. | 77.4 mm of Hg |
| E. | 3.2526 kg/sq-cm |
| Answer» E. 3.2526 kg/sq-cm | |
| 40. |
Which statement is false in case of SI engines |
| A. | Accetylene has least tendency to knocking |
| B. | Adding methyl groups to the side of the carbon chain increases the knocking tendency |
| C. | Unsaturated aliphatic hydrocarbons show less knocking tendency |
| D. | Increasing the length of the carbon chain increases the knocking tendency |
| E. | Centralising the carbon atoms decreases the knocking tendency |
| Answer» A. Accetylene has least tendency to knocking | |
| 41. |
In a petrol engine as the speed increases |
| A. | The spark intensity has to be increased |
| B. | The spark intensity has to be reduced |
| C. | The spark has to be advanced |
| D. | The spark has to be retarded |
| E. | None of the above |
| Answer» D. The spark has to be retarded | |
| 42. |
In thermodynamics, forced processes are those |
| A. | Where a difference is observed in any microscopic property of the system between different times of states |
| B. | Where a difference is observed in any microscopic property of the system between different times or states |
| C. | Which occur in the direction of an intensive property or driving force contained within the system |
| D. | Which require an agency outside the system to force the process |
| E. | None of the above |
| Answer» D. Which require an agency outside the system to force the process | |
| 43. |
The steam in a boiler drum is always |
| A. | Dry and saturated |
| B. | Wet or dry and saturated |
| C. | Dry |
| D. | Wet |
| E. | Superheated |
| Answer» D. Wet | |
| 44. |
Which of the following is false statement? The cause of slow cranking of a gas engine during starting may be |
| A. | Partially discharged battery |
| B. | Under capacity battery |
| C. | High air temperature |
| D. | Heavy engine oil |
| E. | Faulty starting motor |
| Answer» C. High air temperature | |
| 45. |
The work done on a compressor will be least when air is taken from |
| A. | As and where available |
| B. | Source of low temperature air |
| C. | A source at 0?C |
| D. | Atmosphere |
| E. | Source of high temperature air |
| Answer» B. Source of low temperature air | |
| 46. |
A coal contains 3.5% sulphur by weight, as fired, and all the sulphur may be assumed to go to formation of sulphur dioxide. How many tonnes of SO2 are produced per day of the firing rate is 35 tonnes per hour |
| A. | 54.8 |
| B. | 60.8 |
| C. | 48.8 |
| D. | 58.8 |
| E. | 100 |
| Answer» D. 58.8 | |
| 47. |
The total length of 40 mid-ordinates on a simple steam engine indicator diagram is 17 cm. The pressure scale is 0.6 kg/sq-cm. The mean effective pressure would be |
| A. | 1.0 kg/sq-cm |
| B. | 1.7 kg/sq-cm |
| C. | 1.0 kg/sq-cm |
| D. | 10.2 kg/sq-cm |
| E. | None of the above |
| Answer» C. 1.0 kg/sq-cm | |
| 48. |
Free air is air at |
| A. | 1 kg/cm2 and 20?C |
| B. | 1 kg/cm2 and atmospheric temperature |
| C. | 1 kg/cm2 and 27?C |
| D. | 1 kg/cm2 and 0?C |
| E. | Atmospheric conditions at any specific location |
| Answer» E. Atmospheric conditions at any specific location | |
| 49. |
De-Laval turbine is mostly used |
| A. | For small powers at high speeds |
| B. | For small powers at low speeds |
| C. | For high powers at low speeds |
| D. | For high powers at high speeds |
| E. | None of the above |
| Answer» A. For small powers at high speeds | |
| 50. |
Air fuel ratio for a jet engine is of the order of |
| A. | 15 ; 1 |
| B. | 20 ; 1 |
| C. | 60 ; 1 |
| D. | 400 ; 1 |
| E. | 10 ; 1 |
| Answer» C. 60 ; 1 | |
Done Studing? Take A Test.
Great job completing your study session! Now it's time to put your knowledge to the test. Challenge yourself, see how much you've learned, and identify areas for improvement. Don’t worry, this is all part of the journey to mastery. Ready for the next step? Take a quiz to solidify what you've just studied.