McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Uncategorized topics .
| 151. |
The essential conditions for combution are
|
| A. | all correct |
| B. | i and iii |
| C. | ii and iii |
| D. | i and ii |
| Answer» B. i and iii | |
| 152. |
In the rich mixtures used for automobile applications…… |
| A. | fuel quantity is more than stoichiometric quantity |
| B. | air quantity is more than stoichiometric quantity |
| C. | both the quantities are same |
| D. | fuel quantity is more than the air quantity |
| Answer» A. fuel quantity is more than stoichiometric quantity | |
| 153. |
In the Lean mixtures used for automobile applications….. |
| A. | fuel quantity is more than stoichiometric quantity |
| B. | air quantity is more than stoichiometric quantity |
| C. | both quantities are same |
| D. | fuel quantity is more than the air quantity |
| Answer» B. air quantity is more than stoichiometric quantity | |
| 154. |
Stoichiometric air fuel ratio suggests….. |
| A. | correct quantity of fuel-air ratio which gives more economy |
| B. | correct quantity of fuel-air ratio which gives more power |
| C. | correct quantity of fuel-air ratio which gives complete combution |
| D. | all of the above |
| Answer» C. correct quantity of fuel-air ratio which gives complete combution | |
| 155. |
Practical limits of fuel air ratio for combution in SI engines is….. |
| A. | 0.11 to 0.05 |
| B. | 0.2 to 0.1 |
| C. | 0.05 to 0.033 |
| D. | 0.2 to 0.033 |
| Answer» A. 0.11 to 0.05 | |
| 156. |
Practical limits for air fuel ratio in SI engines provides….. |
| A. | range of air fuel ratio which gives comfortable working of si engine |
| B. | range of air fuel ratio to get combustion close to stoichiometric conditions in si engine |
| C. | range of air fuel ratio for obtaining maximum power in si engine |
| D. | all of the above |
| Answer» B. range of air fuel ratio to get combustion close to stoichiometric conditions in si engine | |
| 157. |
Ignition limits in the SI engine depends upon…. |
| A. | mixture ratio and temperature |
| B. | volumetric efficiency and temperature |
| C. | engine size and volumetric efficiency |
| D. | mixture ratio and engine size |
| Answer» A. mixture ratio and temperature | |
| 158. |
Maximum pressure obtained in normal SI engine during motoring is about….. |
| A. | 2 bar |
| B. | 15 bar |
| C. | 8 bar |
| D. | 40 bar |
| Answer» C. 8 bar | |
| 159. |
Pressure during motoring in SI engine compared to CI engine is…. |
| A. | less |
| B. | more |
| C. | same |
| D. | none of the above |
| Answer» A. less | |
| 160. |
Maximum pressure in SI engine is about….. |
| A. | 10 bar |
| B. | 70 bar |
| C. | 50 bar |
| D. | 30 bar |
| Answer» D. 30 bar | |
| 161. |
Approximate temperature produced by spark plug is….. |
| A. | 5,000 deg.celsius |
| B. | 20,000 deg.celsius |
| C. | 2,000 deg.celsius |
| D. | 10,000 deg.celsius |
| Answer» D. 10,000 deg.celsius | |
| 162. |
The preparation phase in SI engine will last for about….. |
| A. | 20 deg. of crank rotation |
| B. | 40 deg. of crank rotation |
| C. | 30 deg. of crank rotation |
| D. | 10 deg. of crank rotation |
| Answer» A. 20 deg. of crank rotation | |
| 163. |
The peak pressure in SI engine will be observed when crank position is…. |
| A. | about 10 deg. before tdc |
| B. | about 10 deg. after tdc |
| C. | at tdc |
| D. | at bdc |
| Answer» B. about 10 deg. after tdc | |
| 164. |
The peak temperature in SI engine will be observed when crank position is…. |
| A. | about 10 deg. before tdc |
| B. | about 10 deg. after tdc |
| C. | at tdc |
| D. | at bdc |
| Answer» B. about 10 deg. after tdc | |
| 165. |
On P.Ѳ. Diagram, start of second phase in the combustion of SI engine is indicated by…. |
| A. | separation of velocity line from compression line |
| B. | constant pressure |
| C. | fall of pressure |
| D. | separation of combustion curve from motoring curve |
| Answer» D. separation of combustion curve from motoring curve | |
| 166. |
On P.Ѳ. Diagram, separation of combustion curve from motoring curve in SI engine takes place… |
| A. | when crank angle is about 10 deg. before tdc |
| B. | when crank angle is about 10 deg. after tdc |
| C. | when crank angle is about 10 deg. before bdc |
| D. | when crank angle is about 10 deg. after bdc |
| Answer» A. when crank angle is about 10 deg. before tdc | |
| 167. |
On P.Ѳ. Diagram, first measurable rise of pressure in SI engine takes place approximately…. |
| A. | when crank angle is about 10 deg. before tdc |
| B. | when crank angle is about 10 deg. after tdc |
| C. | when crank angle is about 10 deg. before bdc |
| D. | when crank angle is about 10 deg. after bdc |
| Answer» B. when crank angle is about 10 deg. after tdc | |
| 168. |
Which phase of combustion takes place during expansion stroke….. |
| A. | ignition lag |
| B. | preparation phase |
| C. | propagation of flame |
| D. | after burning |
| Answer» D. after burning | |
| 169. |
During propagation of flame in SI engine crank rotates by about…. |
| A. | 20 deg. |
| B. | 40 deg. |
| C. | 30 deg. |
| D. | 10 deg. |
| Answer» A. 20 deg. | |
| 170. |
During afterburning phase in SI engine crank rotates by about… |
| A. | 20 deg. |
| B. | 190 deg. |
| C. | 170 deg. |
| D. | 10 deg. |
| Answer» C. 170 deg. | |
| 171. |
Gap size in spark plug electrodes in about…. |
| A. | 10 to 20 mm |
| B. | 1 to 2 mm |
| C. | 0.01 mm to 0.1 mm |
| D. | none of the above |
| Answer» B. 1 to 2 mm | |
| 172. |
As compared to level of fuel in float chamber, the carburettor nozzle opening is at……level |
| A. | same |
| B. | higher |
| C. | lower |
| D. | fluctuating |
| Answer» B. higher | |
| 173. |
SI engines in which diesel is used as a fuel will…… |
| A. | not run at all |
| B. | run with detonation |
| C. | run normally |
| D. | run with less efficiency |
| Answer» A. not run at all | |
| 174. |
If diesel is used in SI engine, it will not run. What is the correct reason? |
| A. | low compression ratio |
| B. | more density |
| C. | less volatility |
| D. | low burning point |
| Answer» C. less volatility | |
| 175. |
Performance number of SI engine fuel |
| A. | corresponds to octane rating |
| B. | relates to the fuels having octane number more than 100 |
| C. | either a or b |
| D. | none of the above |
| Answer» B. relates to the fuels having octane number more than 100 | |
| 176. |
The maximum resistance to detonation is by the fuel |
| A. | iso octane |
| B. | n heptane |
| C. | alpha methyl nonane |
| D. | cetane |
| Answer» A. iso octane | |
| 177. |
A dope or additive is a compound when added in fuel have an effect on |
| A. | decreasing compression ratio |
| B. | increasing self ignition temperature |
| C. | anti knock characteristic |
| D. | none of the above |
| Answer» C. anti knock characteristic | |
| 178. |
Which of the following are dopes for SI engine fuels |
| A. | tel |
| B. | tml |
| C. | phenol |
| D. | all of the above |
| Answer» D. all of the above | |
| 179. |
Addition of ethyl bromide in TEL helps in |
| A. | improving anti knock characteristics |
| B. | reducing anti knock characteristics |
| C. | prevents lead deposits |
| D. | none of the above |
| Answer» C. prevents lead deposits | |
| 180. |
Now a days a unleaded petrol is in the market because |
| A. | it has better anti knock property |
| B. | it is cheaper as compared to leaded petrol |
| C. | lead deposits are poisonous |
| D. | it is highly refined petrol |
| Answer» C. lead deposits are poisonous | |
| 181. |
Stoichiometric air-fuel ratio of petrol engine is roughly |
| A. | 18/1 |
| B. | 25/1 |
| C. | 15/1 |
| D. | 10/1 |
| Answer» C. 15/1 | |
| 182. |
Venturi in the carburettor results in |
| A. | decrease of air velocity |
| B. | increase of air velocity |
| C. | decrease of fuel flow |
| D. | increase of manifold vacuum |
| Answer» B. increase of air velocity | |
| 183. |
The choke is closed when the engine is |
| A. | accelerating |
| B. | hot |
| C. | cold |
| D. | idling |
| Answer» C. cold | |
| 184. |
Lean air mixture is required during |
| A. | idling |
| B. | starting |
| C. | accelerating |
| D. | cruising |
| Answer» D. cruising | |
| 185. |
The limits of air-fuel for SI engine are |
| A. | 8/1 to 18/1 |
| B. | 8/1 to 50/1 |
| C. | 25/1 to 50/1 |
| D. | 50/1 to 100/1 |
| Answer» A. 8/1 to 18/1 | |
| 186. |
In a SI engine for maximum power, relative fuel-air ratio is |
| A. | 1.5 |
| B. | 1.2 |
| C. | 0.8 |
| D. | 0.6 |
| Answer» B. 1.2 | |
| 187. |
For maximum thermal efficincy, the fuel-air ratio mixture in SI engines should be |
| A. | lean |
| B. | rich |
| C. | stoichiometric |
| D. | may be lean or rich |
| Answer» A. lean | |
| 188. |
During starting petrol engines require |
| A. | stoichiometric mixture |
| B. | lean mixture |
| C. | rich mixture |
| D. | any air-fuel ratio is alright |
| Answer» C. rich mixture | |
| 189. |
Economizer is used to provide enriched mixture during |
| A. | starting |
| B. | idling |
| C. | cruising |
| D. | full throttle opening |
| Answer» D. full throttle opening | |
| 190. |
When the throttle is suddenly opened, the mixture from the simple carburettor tends to become |
| A. | rich |
| B. | lean |
| C. | stoichiometric |
| D. | not affected |
| Answer» B. lean | |
| 191. |
Precise petrol injection system is |
| A. | direct injection |
| B. | sequential injection |
| C. | both |
| D. | manifold or port injection system |
| Answer» D. manifold or port injection system | |
| 192. |
The choke in automobile meant for supplying |
| A. | lean mixture |
| B. | rich mixture |
| C. | stoichiometric mixture |
| D. | weak mixture |
| Answer» B. rich mixture | |
| 193. |
Modern carburettor provide the correct quality of air-fuel mixture during |
| A. | starting |
| B. | idling |
| C. | cruising |
| D. | all conditions |
| Answer» D. all conditions | |
| 194. |
A simple carburettor supplies rich mixture during |
| A. | starting |
| B. | idling |
| C. | cruising |
| D. | acceleration |
| Answer» C. cruising | |
| 195. |
Combustion is defined as |
| A. | chemical combination of hydrogen and carbon in the fuel and oxygen in the air |
| B. | chemical combination of hydrogen and carbon in the fuel and nitrogen in the air |
| C. | chemical combination of hydrogen and carbon in the fuel and both oxygen and nitrogen in the air. |
| D. | all the above. |
| Answer» A. chemical combination of hydrogen and carbon in the fuel and oxygen in the air | |
| 196. |
Combustion is defined as |
| A. | rapid oxidation to liberate energy in the form of heat |
| B. | its a chemical reaction of contents of fuel and oxygen in the air to produce energy in the form of heat. |
| C. | both a and b |
| D. | only a |
| Answer» C. both a and b | |
| 197. |
Favourable conditions for combustion are |
| A. | the presence of combustible mixture |
| B. | some means of initiation of combustion |
| C. | stabilization and propagation of flame in the combustion chamber |
| D. | all of the above |
| Answer» D. all of the above | |
| 198. |
Favourable conditions for combustion are |
| A. | the presence of combustible mixture |
| B. | initiation by any means like spark plug is not required |
| C. | stabilization and propagation of flame in the combustion chamber |
| D. | both a and c |
| Answer» D. both a and c | |
| 199. |
Favourable conditions for combustion are: 1. The presence of combustible mixture 2. Initiation by any means like spark plug is not required 3. Stabilization and propagation of flame in the combustion chamber. Out of these following is correct |
| A. | all are correct |
| B. | i and iii |
| C. | ii and iii |
| D. | i and ii |
| Answer» B. i and iii | |
| 200. |
In the rich mixturers used for automobile applications |
| A. | fuel quantity is more than stoichiometric quantity |
| B. | air quantity is more than stoichiometric quantity |
| C. | both the quantities are same |
| D. | fuel quantity is more than the air quantity. |
| Answer» A. fuel quantity is more than stoichiometric quantity | |
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