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Multiple choice question for engineering

Set 1

1. _____________ is that part of an injector through which the liquid fuel is sprayed into the combustion chamber.
a) Governor
b) Nozzle
c) Throttle
d) None of the mentioned

View Answer

Answer: b [Reason:] Nozzle is that part of an injector through which the liquid fuel is sprayed into the combustion chamber while governor is a part used inside engine.

2. _____________ is the first phase in obtaining proper mixing of the fuel and air in the combustion chamber.
a) Vaporization
b) Atomization
c) carburation
d) None of the mentioned

View Answer

Answer: b [Reason:] Atomization is the first phase in obtaining proper mixing of the fuel and air in the combustion chamber whereas vaporization is the escaping of liquid.

3. _____________ the injection pressure better the dispersion and penetration of the fuel into all the desired locations in combustion chamber.
a) Higher
b) Lower
c) Equal
d) None of the mentioned

View Answer

Answer: a

4. If the density of compressed air in the combustion chamber is ____________ then the resistance to the movement of the droplets is higher.
a) high
b) low
c) same
d) none of the mentioned

View Answer

Answer: a [Reason:] When the density of compressed air in the combustion chamber is high then the resistance to the movement of the droplets is higher and dispersion of the fuel is better.

5. Fuel striking the walls of combustion chamber, decomposes and produces _____________ deposits.
a) iron
b) ash
c) carbon
d) none of the mentioned

View Answer

Answer: c [Reason:] When the fuel strikes the walls of combustion chamber, decomposes and produces carbon deposits as it can only be decomposed in carbon and not in iron and ashes.

6. ___________ nozzle is used in open combustion chambers.
a) Single hole
b) Multi hole
c) Circumferential hole
d) none of the mentioned

View Answer

Answer: c [Reason:] The circumferential hole nozzle is used in open type combustion chambers and single or mutli hole nozzle are not used.

7. The size of the hole in a single hole nozzle is usually
a) 0.2 mm
b) < 0.2 mm
c) > 0.2 mm
d) none of the mentioned

View Answer

Answer: c [Reason:] The size of the hole in a single hole nozzle is usually less than 0.2 mm for better sprinkling of fuel.

8. In a single hole nozzle, the spray cone angle varies from
a) 50 to 150
b) 100 to 150
c) 50 to 100
d) none of the mentioned

View Answer

Answer: a [Reason:] The spray cone angle is usually in the range of 50 to 150 in a single hole nozzle.

9. The number of holes in a multi-hole nozzle, varies from
a) 2 to 4
b) 4 to 18
c) 4 to 10
d) none of the mentioned

View Answer

Answer: b [Reason:] The number of holes in a multi-hole nozzle, lies between 4 to 18 depending on the size and requirement of the engine.

10. The hole diameter in a multi-hole nozzle, lies between
a) 0.25 to 0.35 mm
b) 0.20 to 0.30 mm
c) 0.30 to 0.40 mm
d) none of the mentioned

View Answer

Answer: a [Reason:] The hole diameter in a multi-hole nozzle, lies between the range of 0.25 to 0.35 mm for better fuel flow in the combustion chamber.

11. The hole angle in a multi-hole nozzle, lies between
a) 100 to 150
b) 200 to 350
c) 200 to 450
d) none of the mentioned

View Answer

Answer: c [Reason:] The the hole angle in a multi-hole nozzle, lies between 200 to 450 for better fuel combustion.

Set 2

1. The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be
a) 25%
b) 50%
c) 70%
d) 100%

View Answer

Answer: b

2. The efficiency of an Otto cycle is increased by increasing
a) pressure ratio
b) compression ratio
c) temperature ratio
d) none of the mentioned

View Answer

Answer: b

3. The Otto cycle consists of
a) two constant pressure processes and two constant volume processes
b) two constant pressure and two constant entropy processes
c) two constant volume processes and two constant entropy processes
d) none of the mentioned

View Answer

Answer: b

4. The thermal efficiency of theoretical Otto cycle
a) decreases with increase in compression ratio
b) increases with decrease in compression ratio
c) does not depends upon the pressure ratio
d) none of the mentioned

View Answer

Answer: c

5. The work output of theoretical Otto cycle
a) increases with increase in compression ratio
b) increases with increase in pressure ratio
c) both of the mentioned
d) none of the mentioned

View Answer

Answer: c

6. The mean effective pressure of an Otto Cycle increases with an increase in
a) pressure ratio
b) compression ratio
c) temperature ratio
d) none of the mentioned

View Answer

Answer: b [Reason:] The mean effective pressure of an Otto Cycle is directly proportional to its compression ratio, so it increases with an increase in compression ratio.

7. In Otto cycle, heat addition takes place at
a) constant temperature
b) constant pressure
c) constant volume
d) none of the mentioned

View Answer

Answer: c

8. If compression ratio of an engine working on Otto cycle is increased from 5 to 6, its air standard efficiency will increase by
a) 1%
b) 20%
c) 16.67%
d) 8%

View Answer

Answer: d

9. If compression ratio of an engine working on Otto cycle is increased from 5 to 7, the percentage increase in efficiency will be
a) 2%
b) 4%
c) 8%
d) 14%

View Answer

Answer: d

10. The constant volume cycle is also called
a) Carnot cycle
b) Joule cycle
c) Diesel cycle
d) Otto cycle

View Answer

Answer: d

Set 3

1. To prevent blockage of the nozzle by dust particles, the gasoline is filtered by installing a ______________ at the inlet to the float chamber.
a) choke
b) fuel strainer
c) nozzle
d) none of the mentioned

View Answer

Answer: b

2. The strainer consist of
a) a fine wire mesh
b) cone shaped filtering device
c) cylindrical shaped filtering device
d) all of the mentioned

View Answer

Answer: d [Reason:] The strainer may consist of a fine wire mesh or other type of filtering device, cone shaped or cylindrical shaped.

3. The function of a float chamber in a carburetor is to supply the fuel to the nozzle at a
a) constant volume head
b) constant pressure head
c) variable pressure head
d) none of the mentioned

View Answer

Answer: b [Reason:] The function of a float chamber in a carburetor is to supply the fuel to the nozzle at a constant pressure head and not at constant volume or variable pressure.

4. The main metering system of the carburetor controls the fuel feed for
a) cruising
b) full throttle operations
c) all of the mentioned
d) none of the mentioned

View Answer

Answer: c

5. The main metering system of the carburetor consists of
a) the fuel metering orifice through which fuel is drawn from the float chamber
b) the main discharge
c) the passage leading to the idling system
d) all of the mentioned

View Answer

Answer: d

6. The functions of the main metering system are
a) to proportion the fuel-air mixture
b) to decrease the pressure at the discharge nozzle exit
c) to limit the air flow at full throttle
d) all of the mentioned

View Answer

Answer: d

7. The throttle regulates the output of the engine by ________________ the quantity of charge going into the cylinder.
a) constant regulating
b) varying
c) increasing
d) none of the mentioned

View Answer

Answer: b

Set 4

1. A simple carburetor supplies rich mixture during
a) starting
b) idling
c) cruising
d) accelerating

View Answer

Answer: d

2. The size of carburetor is generally given in terms of the diameter of the ______________ in mm.
a) venturi tube
b) jet
c) nozzle
d) none of the mentioned

View Answer

Answer: a [Reason:] The size of carburetor is generally given in terms of the diameter of the venturi tube in mm.

3. A decrease in the density of air ______________ the value of air-fuel ratio.
a) increases
b) reduces
c) equals
d) none of the mentioned

View Answer

Answer: b [Reason:] Generally, a decrease in the density of air reduces the value of air-fuel ratio.

4. Venturi tube is also known as
a) choke tube
b) throat
c) nozzle
d) none of the mentioned

View Answer

Answer: b

5. The pressure difference between the float chamber and the throat of the venturi is known as
a) carburetor expansion
b) carburetor acceleration
c) carburetor depression
d) none of the mentioned

View Answer

Answer: c [Reason:] Carburetor depression is defined as the pressure difference between the float chamber and the throat of the venturi.

6. The choke in an automobile meant is for supplying
a) lean mixture
b) rich mixture
c) stoichiometric mixture
d) weak mixture

View Answer

Answer: b

7. Modern carburettors provide the correct quality of air-fuel mixture during
a) starting
b) idling
c) cruising
d) all of the mentioned

View Answer

Answer: d [Reason:] Modern carburettors provide the correct quality of air-fuel mixture during all the conditions of starting, idling and cruising.

8. The air fuel ratio of the petrol engine is controlled by
a) carburetor
b) injector
c) governor
d) none of the mentioned

View Answer

Answer: a [Reason:] The air fuel ratio of the petrol engine is controlled by carburetor while injector is used to inject fuel and governor is inside engine.

Set 5

1. The rating of a diesel engine, with increase in air inlet temperature, will
a) increase linearly
b) decrease linearly
c) increase parabolically
d) decrease parabolically

View Answer

Answer: b

2. The knock in diesel engine occurs due to
a) instantaneous and rapid burning of the first part of the charge
b) instantaneous auto ignition of last part of charge
c) reduction of delay period
d) none of the mentioned

View Answer

Answer: a

3. Volatility of diesel fuel is
a) maximum temperature to which oil is heated in order to give off inflammable vapour in sufficient quantity to ignite momentarily when bought in contact with a flame
b) it catches fire without external aid
c) indicated by 90% distillation temperature
d) none of the mentioned

View Answer

Answer: c

4. Violent sound pulsations within the cylinder of an I.C. engine are caused due to
a) heavy turbulence
b) improved scavenging
c) detonation
d) pre-ignition

View Answer

Answer: c

5. Auto-ignition temperature is
a) maximum temperature to which oil is heated in order to give off inflammable vapour in sufficient quantity to ignite momentarily when bought in contact with a flame
b) that at which it catches fire without external aid
c) indicated by 90% distillation temperature
d) none of the mentioned

View Answer

Answer: b [Reason:] Auto-ignition temperature is defined as that temperature at which it catches fire without external aid while volatility of diesel fuel is indicated by 90% distillation temperature.

6. Ignition lag is
a) the time taken by fuel after injection to reach upto auto-ignition temperature
b) time before actual fuel injection and the pump plinger starts to pump fuel
c) time corresponding to actual injection and top dead center
d) none of the mentioned

View Answer

Answer: a

7. The delay period in petrol engine is of the order of
a) 0.001 sec
b) 0.002 sec
c) 0.01 sec
d) 0.1 sec

View Answer

Answer: b

8. Detonation is caused by the following unstable compounds
a) peroxides, aldehydes and ketones
b) peroxides, aldehydes, oxides and sulphides
c) aldehydes, oxides and ketones
d) none of the mentioned

View Answer

Answer: a [Reason:] Detonation is caused by peroxides, aldehydes and ketones.

9. In order to prevent knock in the S.I. engines, the charge away from the spark plug should have
a) low temperature
b) low density
c) rich mixture
d) all of the mentioned

View Answer

Answer: d

10. To reduce the possibility of knock in C.I. engines, the first elements of fuel and air should have
a) high temperature
b) high density
c) short delay
d) all of the mentioned

View Answer

Answer: d

11. The detonation tendency in petrol engines for specified conditions of fuel rating, compression ratio, speed etc, can be controlled by having
a) smaller cylinder bore
b) bigger cylinder bore
c) medium cylinder bore
d) none of the mentioned

View Answer

Answer: a

12. A fuel will detonate less if it has
a) higher self ignition temperature
b) lower self ignition temperature
c) proper self ignition temperature
d) none of the mentioned

View Answer

Answer: a

13. Ignition quality of diesel fuel oil is expressed by an index called
a) octane number
b) cetane number
c) calorific value
d) none of the mentioned

View Answer

Answer: b [Reason:] Cetane number is defined as the ignition quality of diesel fuel oil is expressed by an index.

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