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Multiple choice question for engineering

Set 1

1. If the vehicle is operated at an altitude lower than calibration altitude, ___________________ mixture is obtained.
a) lean
b) rich
c) chemically equal
d) none of the mentioned

View Answer

Answer: a [Reason:] If the vehicle is operated at an altitude lower than calibration altitude, generally, lean mixture is obtained.

2. At lower altitude, the vehicles result in
a) hydrocarbon emission
b) carbon monoxide emission
c) poor drivability
d) none of the mentioned

View Answer

Answer: c [Reason:] Generally, at lower altitudes the vehicles result in poor drivability while at higher altitudes the vehicles result in hydrocarbon and carbon monoxide emissions.

3. If the vehicle is operated at an altitude higher than calibration altitude, _______________ mixture is obtained.
a) lean
b) rich
c) chemically equal
d) none of the mentioned

View Answer

Answer: b [Reason:] If The vehicle is operated at an altitude higher than calibration altitude, generally, rich mixture is obtained.

4. At higher altitude, the vehicles result in
a) hydrocarbon emission
b) carbon monoxide emission
c) all of the mentioned
d) none of the mentioned

View Answer

Answer: c [Reason:] At higher altitudes the vehicles result in hydrocarbon and carbon monoxide emissions while at lower altitudes the vehicles result in poor drivability.

5. At higher altitude, power is
a) increased
b) reduced
c) remains same
d) none of the mentioned

View Answer

Answer: b

6. At higher altitude, the mixture strength delivered by the carburetor becomes richer at a rate ___________ proportional to the square root of the density ratio.
a) directly
b) inversely
c) unpredictable
d) none of the mentioned

View Answer

Answer: b

7. At 6,000 m altitude, the air pressure is approximately ________________ the pressure at sea level.
a) same as
b) one-half
c) twice
d) none of the mentioned

View Answer

Answer: b [Reason:] In practical at 6,000 m altitude, the air pressure is approximately one-half the pressure at sea level.

8. The __________________ type of mixture control system, reduces the effective suction on the metering system.
a) back suction
b) needle
c) air port
d) none of the mentioned

View Answer

Answer: a [Reason:] The back suction type of mixture control system, reduces the effective suction on the metering system and the needle type of mixture control system, restricts the flow of fuel through the metering system.

9. The _________________ type of mixture control system, restricts the flow of fuel through the metering system.
a) back suction
b) needle
c) air port
d) none of the mentioned

View Answer

Answer: b [Reason:] The needle type of mixture control system, restricts the flow of fuel through the metering system while the back suction type of mixture control system, reduces the effective suction on the metering system.

10. The ________________ type of mixture control system, allows additional air to enter the carburetor between the main discharge nozzle and the throttle valve.
a) back suction
b) needle
c) air port
d) none of the mentioned

View Answer

Answer: c [Reason:] The air port type of mixture control system, allows additional air to enter the carburetor between the main discharge nozzle and the throttle valve whereas the needle type of mixture control system, restricts the flow of fuel through the metering system while the back suction type of mixture control system, reduces the effective suction on the metering system.

Set 2

1. For idling condition in automotive engines, the air-fuel mixture must be
a) lean
b) rich
c) chemically balanced
d) none of the mentioned

View Answer

Answer: b [Reason:] Generally, for idling condition in automotive engines, the air-fuel mixture must be a rich mixture and for cruising condition in automotive engines, the air-fuel mixture must be a lean mixture.

2. For cruising condition in automotive engines, the air-fuel mixture must be
a) lean
b) rich
c) chemically balanced
d) none of the mentioned

View Answer

Answer: a [Reason:] For cruising condition in automotive engines, the air-fuel mixture must be a lean mixture and for idling condition in automotive engines, the air-fuel mixture must be a rich mixture.

3. For high power condition in automotive engines, the air-fuel mixture must be
a) lean
b) rich
c) chemically balanced
d) none of the mentioned

View Answer

Answer: b [Reason:] For high power condition in automotive engines, the air-fuel mixture must be a rich mixture while for cruising condition in automotive engines, the air-fuel mixture must be a lean mixture and for idling condition in automotive engines, the air-fuel mixture must be a rich mixture.

4. To prevent overheating of exhaust valve and the area near it, the air-fuel mixture must be
a) lean
b) rich
c) chemically balanced
d) none of the mentioned

View Answer

Answer: b

5. In an automobile engine, indication of knocking is available in the form of
a) light
b) gas
c) audible sound
d) none of the mentioned

View Answer

Answer: c [Reason:] Generally, in an automobile engine, indication of knocking is available in the form of audible sound.

6. The operator can make the engine operating conditions less stringent by
a) jamming the throttle
b) releasing the throttle
c) engaging the throttle
d) none of the mentioned

View Answer

Answer: b

7. When the throttle is suddenly opened, the mixture from the simple carburetor tends to become
a) rich
b) lean
c) stoichiometric
d) not affected

View Answer

Answer: b [Reason:] Generally, when the throttle is suddenly opened, the mixture from the simple carburetor tends to become lean.

8. Precise petrol injection system is
a) direct injection
b) sequential injection
c) throttle body injection
d) port injection

View Answer

Answer: c

Set 3

1. A carburetor is used to supply
a) petrol, air and lubricating oil
b) air and diesel
c) petrol and lubricating oil
d) petrol and air

View Answer

Answer: d [Reason:] The purpose of carburetor is to supply petrol and air.

2. The compensating jet in a carburetor supplies almost constant amount of petrol at all speeds because the
a) jet area is automatically varied depending on the suction
b) the flow from the main jet is diverted to the compensating jet with increase in speed
c) the diameter of the jet is constant and the discharge coefficient is invariant
d) flow is produced due to the static head in the float chamber

View Answer

Answer: d

3. Which of the following does not relate to spark ignition engine?
a) Ignition coil
b) Spark plug
c) Carburetor
d) Fuel injector

View Answer

Answer: d [Reason:] Fuel injector is not relate to spark ignition engine as there is no fuel injection in spark ignition engine.

4. Which of the following does not relate to compression ignition engine?
a) Fuel pump
b) Fuel injector
c) Governor
d) Carburetor

View Answer

Answer: d [Reason:] Carburetor is not relate to compression ignition engine.

5. In carburetors, the top of the fuel jet with reference to the level in the float chamber is kept at
a) same level
b) slightly higher level
c) slightly lower level
d) may be anywhere

View Answer

Answer: b

6. Carburetion is done to
a) feed petrol into cylinder
b) govern the engine
c) break up and mix the petrol with air
d) none of the mentioned

View Answer

Answer: c [Reason:] The purpose of carburetion is to break up and mix the petrol with air.

7. Power impulses from IC engine are smoothed out by
a) governor
b) crank shaft
c) gear box
d) flywheel

View Answer

Answer: d [Reason:] Power impulses from IC engine are smoothed out by flywheel as the energy is stored in the flywheel.

8. The following type of carburetor is preferred
a) concentric type
b) eccentric type
c) horizontal type
d) vertical type

View Answer

Answer: a [Reason:] Concentric type of carburetor is preferred as it gives better fuel ratio.

9. In the passenger cars, the following type of carburetor is preferred
a) horizontal type
b) downward draught type
c) upward draught type
d) none of the mentioned

View Answer

Answer: b [Reason:] In the passenger cars, downward draught type of carburetor is preferred to meet the load fuel ratio.

10. The part load efficiency of a carburetor is
a) maximum
b) optimum
c) poor
d) constant

View Answer

Answer: c

Set 4

1. In a carnot cycle, the working medium receives heat at a _____________ temperature.
a) lower
b) higher
c) constant
d) none of the mentioned

View Answer

Answer: b [Reason:] In a carnot cycle the working medium receives heat at a higher temperature and rejects heat at a lower temperature.

2. In a carnot cycle, the working medium rejects heat at a ____________ temperature.
a) lower
b) higher
c) constant
d) none of the mentioned

View Answer

Answer: a [Reason:] In a carnot cycle the working medium receives heat at a higher temperature and rejects heat at a lower temperature.

3. In a carnot cycle, the working fluid is
a) a real gas
b) an ideal gas
c) a natural gas
d) none of the mentioned

View Answer

Answer: b [Reason:] As Carnot cycle is an ideal cycle, so the working fluid is an ideal gas.

4. The isothermal process of a carnot cycle needs very __________ motion of the piston to maintain constant temperature.
a) slow
b) fast
c) medium
d) none of the mentioned

View Answer

Answer: a [Reason:] The isothermal process of a carnot cycle needs very slow motion of the piston to maintain constant temperature while the adiabatic process needs very fast motion to complete the adiabatic process.

5. The adiabatic process of a carnot cycle needs very __________ motion to complete the adiabatic process.
a) slow
b) fast
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] The isothermal process of a carnot cycle needs very slow motion of the piston to maintain constant temperature while the adiabatic process needs very fast motion to complete the adiabatic process.

6. For a given temperature T1, as the difference between T1 and T2 increases, the COP of a carnot heat pump
a) increases
b) decreases
c) first increases, then decreases
d) none of the mentioned

View Answer

Answer: b [Reason:] COP(heat pump) = T1/ (T1 – T2) As the value of T1 – T2 increases, value of COP decreases.

7. A carnot heat pump is used to heat a house. The outside temperature is -3ºC and the indoor temperature is 27ºC. If the heat loss from the house is 40kW, the power required to operate the heat pump is
a) 1kW
b) 2kW
c) 3kW
d) 4kW

View Answer

Answer: d [Reason:] COP(heat pump) = Heat loss/Work done =T1/ (T1 – T2) or, 40/ Work done =273 + 27/27-(-3) or, Work done = 40 x 30/300 = 4kW.

8. A carnot cycle is to be designed to attain efficiency of 0.75. if temperature of high temperature reservoir is 727ºC, then low temperature reservoir will have to be maintained at
a) 23ºC
b) 181ºC
c) -23ºC
d) -181ºC

View Answer

Answer: c [Reason:] Carnot efficiency = T2– T1/ (T2+273) or, 0.75 = 727- T1/(727+273) or, 0.75×1000 = 727- T1 or, – T1 = 750-727 or, T1 = -23ºC.

9. A cyclic heat engine does 50kJ of work per cycle. If efficiency of engine is 75%, the heat rejected per cycle will be
a) 60.6kJ
b) 16.6kJ
c) 66.6kJ
d) 200kJ

View Answer

Answer: b [Reason:] Carnot efficiency = Work done/Heat supplied(Q1) 0.75 = 50/ Q1 or, Q1 = 200/3 and, Work done = Q1– Q2 or, Q2 = 200/3-50 = 50/3 = 16.6kJ.

10. A carnot cycle refrigerator operates between 250ºK and 300ºK. What is the value of COP?
a) 10
b) 20
c) 25
d) 5

View Answer

Answer: d [Reason:] COP = T2/ (T1 – T2) = 250/300-250 = 5.

Set 5

1. Swirl is the rotational flow of charge within the cylinder about the axis.
a) True
b) False

View Answer

Answer: a

2. The _____________ is defined by the parallel portion of the piston and cylinder head which almost touch each other as the piston approaches T.D.C.
a) turbulence
b) swirl
c) quench area
d) none of the mentioned

View Answer

Answer: c [Reason:] The quench area is defined by the parallel portion of the piston and cylinder head which almost touch each other as the piston approaches T.D.C. while turbulence consists of randomly dispersed vortices of different sizes which become superimposed into the air and petrol mixture flow stream.

3. ____________ consists of randomly dispersed vortices of different sizes which become superimposed into the air and petrol mixture flow stream.
a) Turbulence
b) Swirl
c) Quench area
d) None of the mentioned

View Answer

Answer: a [Reason:] Only turbulence consists of randomly dispersed vortices of different sizes which become superimposed into the air and petrol mixture flow stream while quench area is defined by the parallel portion of the piston and cylinder head which almost touch each other as the piston approaches T.D.C.

4. The amount of vortex activity,and the disintegration of others, _____________ the turbulent flow with rising engine speed.
a) increases
b) decreases
c) remains same
d) none of the mentioned

View Answer

Answer: a

5. The degree of turbulence increases _____________ with the piston speed.
a) indirectly
b) directly
c) linearly
d) none of the mentioned

View Answer

Answer: b [Reason:] The degree of turbulence is directly proportional to piston speed, hence it increases directly with the piston speed.

6. Turbulence decreases the heat flow to the cylinder wall and in the limit excessive turbulence may extinguish the flame.
a) True
b) False

View Answer

Answer: b [Reason:] In fact, turbulence increase the heat flow to the cylinder wall and in the limit excessive turbulence may extinguish the flame.

7. The flame propagation velocities range from
a) 10 to 15 m/s
b) 15 to 70 m/s
c) 20 to 80 m/s
d) 30 to 90 m/s

View Answer

Answer: a

8. When ignition occurs the nucleus of the flame spreads with the whirling or rotating vortices in the form of ragged burning crust from the initial spark plug ignition site.
a) True
b) False

View Answer

Answer: a

9. Swirl ratio is defined as the ratio of air rotational speed to crankshaft rotational speed.
a) True
b) False

View Answer

Answer: a

10. Abnormal combustion knock produced by surface ignition in SI engines is not harmful as normal combustion knock.
a) True
b) False

View Answer

Answer: b [Reason:] In fact, abnormal combustion knock produced by surface ignition in SI engines is more harmful than normal combustion knock.