MCQOPTIONS
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MCQOPTIONS
This section includes 513 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The volumetric efficiency of a well-designed engine is in the range |
| A. | 30 to 40% |
| B. | 40 to 609% |
| C. | 60 to 70% |
| D. | 75 to 90% |
| Answer» E. | |
| 102. |
Additives are added in lubricant to have |
| A. | detergent-dispersant characteristics |
| B. | pour point depression |
| C. | antifoam characteristics |
| D. | all of the above |
| Answer» E. | |
| 103. |
Blow by losses are |
| A. | directly proportional to the inlet pressure |
| B. | inversely proportional to the inlet pressure |
| C. | proportional to the square root of inlet pressure |
| D. | none of the above |
| Answer» D. none of the above | |
| 104. |
Supercharging air compressor is driven by |
| A. | exhaust gas turbine |
| B. | engine itself |
| C. | separate electrical motor |
| D. | none of the above |
| Answer» C. separate electrical motor | |
| 105. |
The centrifugal type supercharger is preferable only for |
| A. | low speeds |
| B. | high speeds |
| C. | high pressures |
| D. | none of the above |
| Answer» B. high speeds | |
| 106. |
EFI system can achieve |
| A. | proper injection timing |
| B. | proper injection quantity |
| C. | proper injection pressure |
| D. | all of the above |
| Answer» E. | |
| 107. |
Two-stroke SI engines suffer from |
| A. | fuel loss |
| B. | idling difficulty |
| C. | both (a) and (b) together |
| D. | none of the above |
| Answer» B. idling difficulty | |
| 108. |
The lubricants commonly used in the automobiles are |
| A. | animal oils |
| B. | vegetable oils |
| C. | mineral oils |
| D. | cooking oils |
| Answer» C. mineral oils | |
| 109. |
Thermal efficiency varies |
| A. | inversely as sfc |
| B. | directly as sfc |
| C. | as square as sfc |
| D. | as root as sfc |
| Answer» B. directly as sfc | |
| 110. |
Main advantage of pintaux nozzle is |
| A. | better cold starting performance |
| B. | ability to distribute the fuel |
| C. | good penetration |
| D. | good atomization |
| Answer» B. ability to distribute the fuel | |
| 111. |
Precise petrol injection system is |
| A. | direct injection |
| B. | sequential injection |
| C. | throttle body injection |
| D. | port injection |
| Answer» D. port injection | |
| 112. |
The position of the PCV valve plunger at idle speed is |
| A. | Towards the valve outlet side |
| B. | Towards the valve inlet side |
| C. | Towards the crankcase |
| D. | Near the valve centre |
| Answer» B. Towards the valve inlet side | |
| 113. |
Thermostat is used in radiators to |
| A. | control the velocity of water |
| B. | control distribution of water to various cylinders |
| C. | control the water temperature |
| D. | control the pressure of water |
| Answer» D. control the pressure of water | |
| 114. |
The actual efficiency of a good engine is about _______of the estimated fuel-air cycleefficiency. |
| A. | 100% |
| B. | 85% |
| C. | 50% |
| D. | 25% |
| Answer» C. 50% | |
| 115. |
In MPFI _____ is used to spray fuel into engine. |
| A. | Engine vacuum |
| B. | Suction pressure of engine |
| C. | Electric pump |
| D. | None of the above |
| Answer» C. Electric pump | |
| 116. |
In evaporate cooling systems, heat absorbed per kg of coolant air is equal to |
| A. | Cp Δ t |
| B. | Cv Δ t |
| C. | latent heat of the coolant |
| D. | (Cp – Cv) Δ t |
| Answer» D. (Cp – Cv) Δ t | |
| 117. |
The catalyst used in the converter for oxidizing HC and CO is |
| A. | Copper |
| B. | Charcoal |
| C. | Rodium |
| D. | Platinum |
| Answer» E. | |
| 118. |
Oil pressure in the dry sump lubrication system is around |
| A. | 5 bar - 10 bar |
| B. | 11 bar 15 bar |
| C. | 3 bar - 8 bar |
| D. | 1 bar |
| Answer» D. 1 bar | |
| 119. |
The volumetric efficiency of the SI engine is comparatively |
| A. | lower than CI engine |
| B. | higher than CI engine |
| C. | will be same as CI engine |
| D. | none of the above |
| Answer» B. higher than CI engine | |
| 120. |
Contact breaker should be set |
| A. | just before starting the engine |
| B. | before adjustment of dwell angle |
| C. | after adjustment of dwell angle |
| D. | before setting spark plug gap |
| Answer» D. before setting spark plug gap | |
| 121. |
Stoichiometric air-fuel ratio of petrol is roughly |
| A. | 50:1 |
| B. | 25:1 |
| C. | 15:1 |
| D. | 1:1 |
| Answer» D. 1:1 | |
| 122. |
The volumetric efficiency is affected by |
| A. | the exhaust gas in the clearance volume |
| B. | the design of intake and exhaust valve |
| C. | valve timing |
| D. | all of the above |
| Answer» E. | |
| 123. |
The main purpose of the diverter valve in the air injection system is to |
| A. | Close the check valve |
| B. | Prevent back fire in the exhaust system |
| C. | Prevent backfire in the inlet manifold |
| D. | Weaken the air-fuel mixture |
| Answer» C. Prevent backfire in the inlet manifold | |
| 124. |
Pump used in the forced cooling system is normally |
| A. | piston pump |
| B. | gear pump |
| C. | vane pump |
| D. | centrifugal pump |
| Answer» E. | |
| 125. |
Lean air mixture is required during |
| A. | idling |
| B. | starting |
| C. | accelerating |
| D. | cruising |
| Answer» E. | |
| 126. |
At the same speed two-stroke engine of the same size as a four-stroke engine will develop |
| A. | same power |
| B. | half the power |
| C. | twice the power |
| D. | four times the power |
| Answer» D. four times the power | |
| 127. |
The major loss in a CI engine is |
| A. | direct heat loss |
| B. | loss due to incomplete combustion |
| C. | rubbing friction loss |
| D. | pumping loss |
| Answer» C. rubbing friction loss | |
| 128. |
Brake specific fuel consumption is defined as |
| A. | fuel consumption per hour |
| B. | fuel consumption per km |
| C. | fuel consumption per BP |
| D. | fuel consumption per brake power hour |
| Answer» E. | |
| 129. |
The PCV (Positive Crankcase Ventilation) valve is located between the |
| A. | Air cleaner and the carburetor |
| B. | Carburetor and the intake manifold |
| C. | Intake manifold and air cleaner |
| D. | Intake manifold and crankcase |
| Answer» E. | |
| 130. |
For a given value of r, efficiency of Otto cycle |
| A. | decreases with compression ratio |
| B. | increases with compression ratio |
| C. | is not affected |
| D. | none of the above |
| Answer» C. is not affected | |
| 131. |
Compared to engine driven supercharger the exhaust driven super charger is |
| A. | easy to handle |
| B. | supplies more air |
| C. | utilizes the exhaust energy of the engine |
| D. | matching with engine is easy |
| Answer» D. matching with engine is easy | |
| 132. |
Flame ionization detector is used for measuring |
| A. | CO |
| B. | HC |
| C. | NOx |
| D. | CO2 |
| Answer» C. NOx | |
| 133. |
SI engines are of |
| A. | light weight |
| B. | high speed |
| C. | homogeneous change of fuel and oil |
| D. | all of the above |
| Answer» E. | |
| 134. |
The following factors affect the process of carburetion |
| A. | Engine speed |
| B. | The temperature of incoming air |
| C. | The volatility of fuel |
| D. | All of the above |
| Answer» E. | |
| 135. |
The choke is closed when the engine is |
| A. | accelerating |
| B. | hot |
| C. | cold |
| D. | idling |
| Answer» D. idling | |
| 136. |
Indicated power is directly proportional to |
| A. | torque |
| B. | air consumption |
| C. | cylinder peak pressure |
| D. | none of the above |
| Answer» C. cylinder peak pressure | |
| 137. |
Limitations of air cooling systems are |
| A. | applicable only to large engines |
| B. | cooling is fast |
| C. | higher working temperature compared to water cooling |
| D. | all of the above |
| Answer» D. all of the above | |
| 138. |
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» C. not affected | |
| 139. |
For a four cylinder engine operating at N rpm, the contact breaker must make and break thecircuit |
| A. | N times |
| B. | 2N times |
| C. | N/2 times |
| D. | none of the above |
| Answer» C. N/2 times | |
| 140. |
As the compression ratio increases, there is a |
| A. | large increase in heat rejection |
| B. | large decrease in heat reduction |
| C. | marginal increase in heat rejection |
| D. | marginal reduction in heat rejection |
| Answer» E. | |
| 141. |
In a three-way converter, the first converter controls |
| A. | HC |
| B. | CO |
| C. | NOx |
| D. | All of these |
| Answer» D. All of these | |
| 142. |
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» D. not affected | |
| 143. |
Cooling after compression is necessary to |
| A. | increase the density of air |
| B. | reduce engine operating temperatures |
| C. | both (a) and (b) |
| D. | increase exhaust temperature |
| Answer» D. increase exhaust temperature | |
| 144. |
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» B. 1.0 and 1.1 | |
| 145. |
Engines of different cylinder dimensions, power and speed can be compared on the basis of |
| A. | Maximum pressure |
| B. | Fuel consumption |
| C. | mean effective pressure |
| D. | unit power |
| Answer» D. unit power | |
| 146. |
For SI engines fuels most preferred are |
| A. | aromatics |
| B. | parafins |
| C. | olefins |
| D. | napthenes |
| Answer» B. parafins | |
| 147. |
The ratio of the actual efficiency and the fuel-air cycle efficiency for CI engines is about |
| A. | 0.2-0.3 |
| B. | 0.5-0.6 |
| C. | 1.0 |
| D. | 0.6-0.8 |
| Answer» E. | |
| 148. |
Disadvantages of reciprocating IC engine are |
| A. | vibration |
| B. | use of fossil fuels |
| C. | balancing problems |
| D. | all of the above |
| Answer» E. | |
| 149. |
A two-stroke engine can be identified by |
| A. | cooling system |
| B. | lubrication system |
| C. | absence of valves |
| D. | piston size |
| Answer» D. piston size | |
| 150. |
What is the factor on which, difference between the two heating values of fuel depends on? |
| A. | Physical properties |
| B. | Reactants |
| C. | Chemical composition |
| D. | Products |
| Answer» D. Products | |