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# Multiple choice question for engineering

## Set 1

1. Dual Cycle is a combination of
a) Otto cycle and Diesel cycle
b) Otto cycle and Stirling cycle
c) Brayton cycle and steam cycle
d) None of the mentioned

2. Dual cycle is also known as
a) Diesel cycle
b) Joule cycle
c) Mixed cycle
d) None of the mentioned

Answer: c [Reason:] Another name for Dual cycle is mixed cycle.

3. In Dual cycle, heat addition takes place
a) at Constant volume
b) first at constant volume then at constant pressure
c) constant pressure
d) none of the mentioned

Answer: b [Reason:] Since, Dual Cycle is a combination of Otto cycle and Diesel cycle, so in Dual cycle, generally heat addition takes place first at constant volume then at constant pressure.

4. In Dual cycle, heat rejection takes place
a) at Constant volume
b) first at constant volume then at constant pressure
c) constant pressure
d) none of the mentioned

Answer: a [Reason:] Since, Dual Cycle is a combination of Otto cycle and Diesel cycle, so in Dual cycle, generally heat rejection takes place at constant volume.

5. Most high speed compression engines operate on
a) Otto cycle
b) Diesel Cycle
c) Dual cycle
d) Carnot cycle

6. In a standard dual air cycle, for a fixed amount of heat supplied and a fixed value of compression ratio, the mean effective pressure
a) shall increase with increase in rp and decreases in rc
b) shall increase with decrease in rp and increases in rc
c) shall remain independent of rp
d) shall remain independent of rc

7. The thermal efficiency of a diesel engine on weak mixtures is
a) unaffected
b) lower
c) higher
d) none of the mentioned

8. The volumetric efficiency of a well designed engine may be
a) 30 to 40%
b) 40 to 60%
c) 60 to 70%
d) 75 to 90%

## Set 2

1. The normal heptane(C7H16) is given a rating of ____________ octane number.
a) 0
b) 50
c) 100
d) 120

2. A fuel of an octane number rating of 75 matches in knocking intensity as a mixture of
a) 75% iso-octane and 25% normal heptane
b) 75% normal heptane and 25% iso-octane
c) 75% petrol and 25% diesel
d) 75% diesel and 25% petrol

3. The two reference fuels used for cetane rating are
a) cetane and iso-octane
b) cetane and alpha-methyl naphthalene
c) cetane and normal heptane
d) none of the mentioned

Answer: b [Reason:] Cetane and alpha-methyl naphthalene are the reference fuels taken for cetane rating.

4. A mixture containing 65% of iso-octane and 35% of normal heptane will have
a) cetane number 65
b) octane number 65
c) cetane number 35
d) octane number 35

Answer: b [Reason:] A mixture containing 65% of iso-octane and 35% of normal heptane will have octane number 65 as octane number is the number percentage containing iso-octane.

5. A fuel of cetane number 40 has the same ignition quality as a mixture of
a) 40% cetane and 60% alpha methyl naphthalene
b) 40% alpha methyl naphthalene and 60% cetane
c) 40% petrol and 60% diesel
d) 40% diesel and 60% petrol

Answer: a [Reason:] A fuel of cetane number 40 has the same ignition quality as a mixture of 40% cetane and 60% alpha methyl naphthalene as cetane number is counted on cetane percentage.

6. Anti-knock for compression ignition engines is
a) napthene
c) amyl nitrate

Answer: c [Reason:] Amyl nitrate is the anti-knock for compression ignition engines.

7. The fuels in order of decreasing knock tendency for spark ignition engines are
a) paraffins, aromatics, napthenes
b) paraffins, napthanes, aromatics
c) napthenes, aromatics, paraffins
d) none of the mentioned

Answer: b [Reason:] Paraffins have the highest knocking tendency, while napthanes have less knocking than paraffina and aromatics have the lowest knocking tendency.

8. Which of the following fuel has little tendency towards detonation?
a) Benzene
b) Iso-octane
c) Normal heptane
d) Alcohol

Answer: b [Reason:] Benzene has little tendency towards detonation.

9. Which of the following fuel detonates readily?
a) Benzene
b) Iso-octane
c) Normal heptane
d) Alcohol

10. The knocking tendency in spark ignition engines can be decreased by adding dopes like tetra ethyle lead and ethylene dibromide.
a) True
b) False

## Set 3

1. The knock limit is dependent upon
a) the type of fuel used
b) mixture ratio
d) all of the mentioned

Answer: d [Reason:] The knock limit is dependent upon the following factors a) the type of fuel used b) mixture ratio c) spark advance d) design feature of the engine.

2. For volatile petroleum fuels of high octane number, the knocking is reduced at _____________ mixture.
a) very rich
b) very lean
c) equal
d) none of the mentioned

Answer: a [Reason:] It has been observed that for volatile petroleum fuels of high octane number, the knocking is reduced at very rich mixture and reduces pre-ignition at very lean mixture.

3. For volatile petroleum fuels of high octane number, pre-ignition is reduced at _____________ mixture.
a) very rich
b) very lean
c) equal
d) none of the mentioned

Answer: b [Reason:] For volatile petroleum fuels of high octane number, pre-ignition is reduced at very lean mixture while the knocking is reduced at very rich mixture.

4. In alcoholic fuels the knock is reduced at _____________ mixtures.
a) rich
b) lean
c) equal
d) none of the mentioned

Answer: a [Reason:] In alcoholic fuels the knock is reduced at rich mixtures because of the cooling effect of high latent heat of the fuel.

5. A slight ___________ in lean mixture makes the engine operation irregular and intermittent.
a) increase
b) reduction
c) heat
d) none of the mentioned

Answer: b [Reason:] Very lean and very rich mixtures give non-knocking operations, and as a reason a slight reduction in lean mixture makes the engine operation irregular and intermittent.

6. The ignition timings and thermal load on the engine affect the knock limit of _____________ engine.
a) SI
b) CI
c) All of the mentioned
d) None of the mentioned

Answer: a [Reason:] The ignition timings and thermal load on the engine affect the knock limit of SI engine while there is no such case in CI engine.

7. The pressure of supercharger used is
a) 1.0 to 1.3 bar
b) 1.2 to 1.4 bar
c) 1.3 to 1.5 bar
d) none of the mentioned

Answer: c [Reason:] In general, supercharger pressure of 1.3 to 1.5 bar is used, which corresponds to about 30 to 50 percent supercharging.

8. In CI engine, the power developed by the turbocharger is sufficient to drive the compressor, and overcome mechanical friction.
a) True
b) False

Answer: a [Reason:] In CI engine there is no use of superchargers, as in case of SI engines, so the power from turbocharger is sufficient to drive the compressor, and overcome mechanical friction.

9. Increase in pressure and temperature of the intake air increases significantly delay and rate of pressure.
a) True
b) False

Answer: b [Reason:] Increase in pressure and temperature of the intake air reduces significantly delay and rate of pressure.

10. The speed range of turbocharger is from
a) 10000 to 20000 r.p.m
b) 20000 to 30000 r.p.m
c) 30000 to 40000 r.p.m
d) none of the mentioned

Answer: b [Reason:] The speed range of turbocharger is from 20000 to 30000 r.p.m.

## Set 4

1. The ECU in the electronic control system, receives signals from the sensors and determines the opening time for the injectors land which also controls the injection volume.
a) True
b) False

2. When the engine is cold, the starting of the engine is usually not
a) difficult
b) easy
c) all of the mentioned
d) none of the mentioned

Answer: b [Reason:] The starting of the engine is usually not easy when the engine is cold.

3. When a cold engine is started, it requires a _____________ mixture.
a) leaner
b) richer
c) chemically equal
d) none of the mentioned

Answer: b [Reason:] For starting a cold engine, generally a richer mixture is required.

4. The cold start injector is a type of solenoid valve to which power is supplied from a battery for the opening and closing of the valve inside, thus for injecting the fuel.
a) True
b) False

5. The duration of injection time is controlled by a timing switch.
a) True
b) False

6. The ignition switch is composed of a bi-metal element and an electric heater coil.
a) True
b) False

Answer: b [Reason:] No, but in fact, the timing switch is composed of a bi-metal element and an electric heater coil.

7. As the temperature is low, the _____________ valve speeds up the engine idle speed to fast idling.
a) nozzle
b) throttle
c) air
d) None of the mentioned

Answer: c [Reason:] At low temperature, the air valve speeds up the engine idle speed to fast idling and not the throttle or nozzle.

8. When the engine is cold, the _____________ plate will be in closed position.
a) nozzle
b) throttle
c) air
d) None of the mentioned

Answer: b [Reason:] Generally, when the engine is cold, the throttle plate will be in closed position and at low temperature, the air valve speeds up the engine idle speed to fast idling.

9. When the engine reaches the normal operating temperature, the valve closes completely and the air flow is cut-off from the _____________ valve.
a) nozzle
b) throttle
c) air
d) None of the mentioned

Answer: c [Reason:] Generally, when the engine reaches the normal operating temperature, the valve closes completely and the air flow is cut-off from the air valve.

10. A thermo wax valve operates depending on the temperature of the engine coolant.
a) True
b) False

## Set 5

1. _____________ senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio.
a) Engine temperature
b) Exhaust gas
c) Air flow
d) Air inlet temperature

Answer: b [Reason:] Exhaust gas senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio while engine temperature sensor senses the temperature of the engine coolant, and from this data the computer adjusts the mixture strength to rich side for cold starting.

2. In _____________ sensor, output voltage changes in proportion to air-fuel ratio.
a) engine temperature
b) exhaust gas
c) air flow
d) air inlet temperature

Answer: b [Reason:] Only in exhaust gas sensor, output voltage changes in proportion to air-fuel ratio.

3. The _____________ sensor senses the temperature of the engine coolant, and from this data the computer adjusts the mixture strength to rich side for cold starting.
a) engine temperature
b) exhaust gas
c) air flow
d) air inlet temperature

Answer: a [Reason:] The engine temperature sensor senses the temperature of the engine coolant, and from this data the computer adjusts the mixture strength to rich side for cold starting while the air flow sensor, monitors mass or volume of air flowing into the intake manifold for adjusting the quantity of fuel and exhaust gas senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio.

4. The _____________ sensor, monitors mass or volume of air flowing into the intake manifold for adjusting the quantity of fuel.
a) engine temperature
b) exhaust gas
c) air flow
d) air inlet temperature

Answer: c [Reason:] The air flow sensor, monitors mass or volume of air flowing into the intake manifold for adjusting the quantity of fuel while exhaust gas senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio.

5. The _____________ sensor, checks the temperature of the ambient air entering the engine for fine tuning the mixture strength.
a) engine temperature
b) exhaust gas
c) air flow
d) air inlet temperature

Answer: d [Reason:] The air inlet temperature sensor, checks the temperature of the ambient air entering the engine for fine tuning the mixture strength whereas the engine temperature sensor senses the temperature of the engine coolant, and from this data the computer adjusts the mixture strength to rich side for cold starting while the air flow sensor, monitors mass or volume of air flowing into the intake manifold for adjusting the quantity of fuel and exhaust gas senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio.

6. The _____________ sensor, senses the movement of the throttle plate so that the mixture flow can be adjusted for engine speed and acceleration.
a) throttle position
b) manifold pressure
c) camshaft position
d) knock

Answer: a [Reason:] The throttle position sensor, senses the movement of the throttle plate so that the mixture flow can be adjusted for engine speed and acceleration while the manifold pressure sensor, monitors vacuum in the engine intake manifold so that the mixture strength can be adjusted with changes in engine load and the camshaft position sensor, senses rotation of engine camshaft for speed and timing of injection.

7. The ___________ sensor, monitors vacuum in the engine intake manifold so that the mixture strength can be adjusted with changes in engine load.
a) throttle position
b) manifold pressure
c) camshaft position
d) knock

Answer: b [Reason:] The manifold pressure sensor, monitors vacuum in the engine intake manifold so that the mixture strength can be adjusted with changes in engine load and the camshaft position sensor, senses rotation of engine camshaft for speed and timing of injection.

8. The _____________ sensor, senses rotation of engine camshaft for speed and timing of injection.
a) throttle position
b) manifold pressure
c) camshaft position
d) knock

Answer: c [Reason:] The camshaft position sensor, senses rotation of engine camshaft for speed and timing of injection whereas the throttle position sensor, senses the movement of the throttle plate so that the mixture flow can be adjusted for engine speed and acceleration while the manifold pressure sensor, monitors vacuum in the engine intake manifold so that the mixture strength can be adjusted with changes in engine load.

9. The _____________ sensor,is a microphone type sensor that detects ping or pre-ignition noise so that the ignition timing can be retarded.
a) throttle position
b) manifold pressure
c) camshaft position
d) knock

Answer: d [Reason:] The knock sensor,is a microphone type sensor that detects ping or pre-ignition noise so that the ignition timing can be retarded while the camshaft position sensor, senses rotation of engine camshaft for speed and timing of injection whereas the throttle position sensor, senses the movement of the throttle plate so that the mixture flow can be adjusted for engine speed and acceleration while the manifold pressure sensor, monitors vacuum in the engine intake manifold so that the mixture strength can be adjusted with changes in engine load.

10. In electronic fuel injection, there is improvement in the _____________ efficiency due to comparatively less resistance in the intake manifolds which will cause less pressure losses.
a) mechanical
b) volumetric
c) overall
d) none of the mentioned