McqMate
Chapters
| 1. |
In SI engines maximum flame speed is obtained when the equivalent ratio is between |
| A. | 1.1 and 1.2 |
| B. | 1.0 and 1.1 |
| C. | 1.2 and 1.3 |
| D. | less than 1 |
| Answer» A. 1.1 and 1.2 | |
| 2. |
In SI engines flame speed increases |
| A. | with turbulence |
| B. | with fuel-air ratio |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» C. both (a) and (b) | |
| 3. |
with increase in compression ratio flame speed |
| A. | increases |
| B. | decreases |
| C. | remains the same |
| D. | none of the above |
| Answer» A. increases | |
| 4. |
With increase in speed the crank angle required for fame propagation |
| A. | increases |
| B. | decreases |
| C. | not affected |
| D. | none of the above |
| Answer» C. not affected | |
| 5. |
Increasing the compression ratio in SI engines the knocking tendency |
| A. | decreases |
| B. | increases |
| C. | not affected |
| D. | none of the above |
| Answer» B. increases | |
| 6. |
Decreasing the cooling water temperature in SI engines the knocking tendency |
| A. | increases |
| B. | decreases |
| C. | not affected |
| D. | none of the above |
| Answer» B. decreases | |
| 7. |
Detonation in SI engines occur due to |
| A. | pre ignition of the charge before the spark |
| B. | sudden ignition of the charge before the spark |
| C. | autoignition of the charge after the spark in struck |
| D. | none of the above |
| Answer» C. autoignition of the charge after the spark in struck | |
| 8. |
Desirable characteristics of the combustion chamber for SI engines to avoid knock is |
| A. | small bore |
| B. | short ratio of fame path to bore |
| C. | absence of hot surfaces in the last region of the charge |
| D. | all of the above |
| Answer» D. all of the above | |
| 9. |
In CI engines with increase in compression ratio the delay period |
| A. | increases |
| B. | decreases |
| C. | first increases and then decreases |
| D. | not affected |
| Answer» C. first increases and then decreases | |
| 10. |
Knocking takes place in CI engines |
| A. | at the start of combustion |
| B. | at the end of combustion |
| C. | during combustion |
| D. | none of the above |
| Answer» A. at the start of combustion | |
| 11. |
In CI engines knocking tendency increases with |
| A. | increase in compression ratio |
| B. | increasing inlet temperature of air |
| C. | decrease in compression ratio |
| D. | increasing coolant water temperature |
| Answer» C. decrease in compression ratio | |
| 12. |
In CI engines by increasing inlet air pressure the knocking tendency |
| A. | increases |
| B. | decreases |
| C. | not affected |
| D. | first decreases and then increases |
| Answer» B. decreases | |
| 13. |
Open combustion chambers in CI engines require |
| A. | high injection pressures |
| B. | accurate metering of fuel by the injection system |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» C. both (a) and (b) | |
| 14. |
The advantages of the indirect injection combustion chambers are |
| A. | low injection pressure |
| B. | direction of spray is not critical |
| C. | both (a) and (b) |
| D. | good cold starting performance |
| Answer» C. both (a) and (b) | |
| 15. |
In CI engines the delay period is affected by |
| A. | compression ratio |
| B. | engine speed |
| C. | output |
| D. | all of the above |
| Answer» D. all of the above | |
| 16. |
Crankcase explosion in I.C. engines usually occurs as |
| A. | first a mild explosion followed by a bi explosion |
| B. | first a big explosion followed by a mil explosion |
| C. | both mild and big explosions occi simultaneously |
| D. | never occurs |
| Answer» A. first a mild explosion followed by a bi explosion | |
| 17. |
Compression loss in I.C engines occurs duto |
| A. | leaking piston rings |
| B. | use of thick head gasket |
| C. | clogged air-inlet slots |
| D. | all of the above. |
| Answer» D. all of the above. | |
| 18. |
It the temperature of intake air in IC engines is lowered, then its efficiency will |
| A. | increase |
| B. | decrease |
| C. | remain same |
| D. | increase upto certain limit and then decrease |
| Answer» A. increase | |
| 19. |
The precess of breaking up or a liquid into fine droplets by spraying is called |
| A. | vaporisation |
| B. | carburetion |
| C. | ionisation |
| D. | atomisation. |
| Answer» D. atomisation. | |
| 20. |
As a result of detonation in an I.C. engine, following parameter attains very high value |
| A. | peak pressure |
| B. | rate of rise of pressure |
| C. | rate of rise of temperature |
| D. | peak temperature |
| Answer» B. rate of rise of pressure | |
| 21. |
Which of the following statements is correct? |
| A. | All the irreversible engines have same efficiency |
| B. | All the reversible engines have same efficiency |
| C. | Both Rankine and Caront cycles have same efficiency between same temperature limits |
| D. | All reversible engines working between same temperature limits have same-efficiency |
| Answer» D. All reversible engines working between same temperature limits have same-efficiency | |
| 22. |
The accumulation of carbon in a cylinder results in increase of |
| A. | clearance volume |
| B. | volumetric efficiency |
| C. | ignition time |
| D. | effective compression ratio |
| Answer» D. effective compression ratio | |
| 23. |
In diesel engine the diesel fuel injected intc cylinder would burn instantly at about compressed air temperature of |
| A. | 250°C |
| B. | 500°C |
| C. | 1000°C |
| D. | 150CPC |
| Answer» C. 1000°C | |
| 24. |
In a cycle, the spark lasts roughly for |
| A. | 1 sec |
| B. | 0.1 sec |
| C. | 0.01 sec |
| D. | 0.001 sec |
| Answer» D. 0.001 sec | |
| 25. |
Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following |
| A. | piston ring and cylinder wear |
| B. | formation of hard coating on piston skirts |
| C. | oil sludge in the engine crank case |
| D. | detonation |
| Answer» D. detonation | |
| 26. |
Which of the following is false statement. Some of the methods used to reduce diesel smoke are as follows |
| A. | using additives in the fuel |
| B. | engine derating i.e. reducing the maxi-mum flow of fuel |
| C. | increasing the compression ratio |
| D. | adherence to proper fuel specification |
| Answer» C. increasing the compression ratio | |
| 27. |
A high flame speed is obtained in diesel engine when air fuel ratio is |
| A. | uniform throughout the mixture |
| B. | chemically correct mixture |
| C. | about 3-5% rich mixture |
| D. | about 10% rich mixture |
| Answer» D. about 10% rich mixture | |
| 28. |
The knock in diesel engine occurs due to |
| A. | instantaneous and rapid burning of the first part of the charge |
| B. | instantaneous atuo iginition of last part of charge |
| C. | delayed burning of the first part of the charge |
| D. | reduction of delay period |
| Answer» A. instantaneous and rapid burning of the first part of the charge | |
| 29. |
A stoichiometric air-fuel ratio is |
| A. | chemically correct mixture |
| B. | lean mixture |
| C. | rich mixture for idling |
| D. | rich mixture for over loads |
| Answer» A. chemically correct mixture | |
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