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Multiple choice question for engineering

Set 1

1. The electronic fuel injection, eliminates majority of carburettor pressure loses and almost eliminates the requirement of manifold heating.
a) True
b) False

View Answer

Answer: a

2. Manifold _____________ is eliminated due to the fuel being injected into or close to the cylinder and need not flow through the manifold.
a) heating
b) wetting
c) cooling
d) none of the mentioned

View Answer

Answer: b [Reason:] Generally, manifold wetting is eliminated due to the fuel being injected into or close to the cylinder and need not flow through the manifold and not heating or cooling.

3. _____________ of fuel is independent of cranking speed and therefore starting will be easier.
a) Ignition
b) Atomization
c) Condensation
d) None of the mentioned

View Answer

Answer: b [Reason:] Atomization of fuel is independent of cranking speed and therefore starting will be easier and ignition and condensation are not related to cranking speed.

4. Better atomization and _____________ will make the engine less knock prone.
a) ignition
b) vapourization
c) condensation
d) none of the mentioned

View Answer

Answer: b [Reason:] Engine knock is dependent on poor atomization and vapourization conditions, so better atomization and vapourization will make the engine less knock prone.

5. Formation of ice on the _____________ plate is eliminated in electronic fuel injection.
a) throttle
b) nozzle
c) engine
d) none of the mentioned

View Answer

Answer: a [Reason:] Generally, formation of ice on the throttle plate is eliminated in electronic fuel injection and not of nozzle.

6. In an electronic fuel injection, variation of air-fuel ratio is almost negligible even when the vehicle takes different positions like turning, moving on gradients, uneven roads etc.
a) True
b) False

View Answer

Answer: a

7. In an electronic fuel injection, position of the injection unit is critical.
a) True
b) False

View Answer

Answer: b [Reason:] No, in fact, in an electronic fuel injection, position of the injection unit is not so critical and thereby the height of the engine can be less.

8. In an electronic fuel injection, the maintenance cost is
a) low
b) high
c) nil
d) none of the mentioned

View Answer

Answer: b [Reason:] Generally, in an electronic fuel injection, the maintenance cost is high.

9. In an electronic fuel injection, the servicing is very
a) difficult
b) easy
c) nil
d) none of the mentioned

View Answer

Answer: a [Reason:] The servicing is very difficult in an electronic fuel injection.

10. In an electronic fuel injection, there is a possibility of malfunctioning of some sensors.
a) True
b) False

View Answer

Answer: a

Set 2

1. The ratio of the heat equivalent to one kW hour to the heat in fuel per B.P. hour is termed as brake thermal efficiency.
a) True
b) False

View Answer

Answer: a [Reason:] Brake thermal efficiency is defined as the ratio of the heat equivalent to one kW hour to the heat in fuel per B.P. hour.

2. The ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time is called
a) mechanical efficiency
b) overall efficiency
c) indicated thermal efficiency
d) volumetric efficiency

View Answer

Answer: b [Reason:] Overall efficiency is the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time while mechanical efficiency is the ratio of the brake power to the indicated power and relative efficiency is the ratio of the indicated thermal efficiency to the air standard efficiency.

3. The ratio of the brake power to the indicated power is called
a) mechanical efficiency
b) overall efficiency
c) indicated thermal efficiency
d) volumetric efficiency

View Answer

Answer: a [Reason:] Mechanical efficiency is the ratio of the brake power to the indicated power and relative efficiency is the ratio of the indicated thermal efficiency to the air standard efficiency whereas overall efficiency is the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time.

4. The ratio of the indicated thermal efficiency to the air standard efficiency is known as
a) mechanical efficiency
b) overall efficiency
c) relative efficiency
d) volumetric efficiency

View Answer

Answer: c [Reason:] Relative efficiency is the ratio of the indicated thermal efficiency to the air standard efficiency whereas overall efficiency is the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time and mechanical efficiency is the ratio of the brake power to the indicated power.

5. The correct sequence of the decreasing order of brake thermal efficiency of the three given basic types of engines is
a) four stroke C.I. engine, four stroke S.I. engine, two stroke S.I. engine
b) four stroke S.I. engine, four stroke C.I. engine, two stroke S.I. engine
c) four stroke C.I. engine, two stroke S.I. engine, four stroke S.I. engine
d) two stroke S.I. engine, four stroke S.I. engine, four stroke C.I. engine

View Answer

Answer: a [Reason:] The brake thermal efficiency of the three given basic types of engines decreases in the order four stroke C.I. engine, four stroke S.I. engine, two stroke S.I. engine.

6. The brake power of a diesel engine, keeping other parameters constant, can be increased by
a) decreasing the density of intake air
b) increasing the temperature of intake air
c) increasing the pressure of intake air
d) decreasing the pressure of intake air

View Answer

Answer: c [Reason:] By increasing the pressure of intake air, the brake power of a diesel engine, keeping other parameters constant, can be increased and by no other means.

7. Which one of the following event would reduce volumetric efficiency of a vertical compression ignition engine?
a) inlet valve closing after bottom dead center
b) inlet valve closing before bottom dead center
c) inlet valve opening before top dead center
d) exhaust valve closing after top dead center

View Answer

Answer: b [Reason:] Volumetric efficiency of a vertical compression ignition engine is reduced by closing inlet valve before bottom dead center.

8. As compared to air standard cycle, in actual working, the effect of variation in specific heats is to
a) increase maximum pressure and maximum temperature
b) decrease maximum pressure and maximum temperature
c) increase maximum pressure and decrease maximum temperature
d) decrease maximum pressure and increase maximum temperature

View Answer

Answer: b [Reason:] In actual working, as compared to air standard cycle, the effect of variation in specific heats is to decrease maximum pressure and maximum temperature.

9. The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called
a) mechanical efficiency
b) overall efficiency
c) relative efficiency
d) volumetric efficiency

View Answer

Answer: d [Reason:] Volumetric efficiency is the ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston while mechanical efficiency is the ratio of the brake power to the indicated power and relative efficiency is the ratio of the indicated thermal efficiency to the air standard efficiency whereas overall efficiency is the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time.

10. The overall efficiency is defined as the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time.
a) True
b) False

View Answer

Answer: a

Set 3

1. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
a) net efficiency
b) efficiency ratio
c) relative efficiency
d) overall efficiency

View Answer

Answer: c [Reason:] Relative efficiency is defined as the ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency.

2. Compression ratio of I.C. engine is
a) the ratio of volumes of air in cylinder before compression stroke and after compression stroke.
b) volume displaced by piston per stroke and clearance volume in cylinder.
c) ratio of pressure after compression and before compression.
d) swept volume/cylinder volume.

View Answer

Answer: a

3. The air standard efficiency of an otto cycle compared to diesel cycle for the given compression ratio is
a) same
b) less
c) more
d) more or less depending on power rating

View Answer

Answer: c

4. The calorific value of gaseous fuels is expressed in terms of
a) Kcal
b) Kcal/kg
c) Kcal/m2
d) Kcal/m3

View Answer

Answer: d

5. Indicated power of a 4-stroke engine is equal to
a) pLAN
b) 2pLAN
c) pLAN/2
d) 4pLAN
where p = mean effective pressure,
L = stroke
A = area of piston and
N = rpm of engine

View Answer

Answer: c [Reason:] Indicated power of a 4-stroke engine is equal to pLAN/2.

6. If the intake air temperature of I.C. engine increases its efficiency will
a) increase
b) decrease
c) remain same
d) none of the mentioned

View Answer

Answer: b

7. All heat engines utilize
a) low heat value of oil
b) high heat value of oil
c) net calorific value of oil
d) calorific value of fuel

View Answer

Answer: a

8. An engine indicator is used to determine the following
a) speed
b) temperature
c) volume of cylinder
d) m.e.p and I.H.P

View Answer

Answer: d

9. Fuel oil consumption guarantees for I.C. engine are usually based on
a) low heat value of oil
b) high heat value of oil
c) net calorific value of oil
d) calorific value of fuel

View Answer

Answer: b

10. The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will
a) increase
b) decrease
c) be independent
d) none of the mentioned

View Answer

Answer: b

Set 4

1. The total power developed by combustion of fuel in the combustion chamber is called
a) brake power
b) indicated power
c) mean effective pressure
d) none of the mentioned

View Answer

Answer: b [Reason:] Indicated power is defined as the total power developed by combustion of fuel in the combustion chamber while brake power is defined as the power developed by an engine at the output shaft and mean effective pressure is defined as the hypothetical pressure which is thought to be acting on the piston throughout the power stroke.

2. The power developed by an engine at the output shaft is called
a) brake power
b) indicated power
c) mean effective pressure
d) none of the mentioned

View Answer

Answer: a [Reason:] Brake power is defined as the power developed by an engine at the output shaft while indicated power is defined as the total power developed by combustion of fuel in the combustion chamber and mean effective pressure is defined as the hypothetical pressure which is thought to be acting on the piston throughout the power stroke.

3. The hypothetical pressure which is thought to be acting on the piston throughout the power stroke is called
a) brake power
b) indicated power
c) mean effective pressure
d) none of the mentioned

View Answer

Answer: c [Reason:] Mean effective pressure is defined as the hypothetical pressure which is thought to be acting on the piston throughout the power stroke and brake power is defined as the power developed by an engine at the output shaft while indicated power is defined as the total power developed by combustion of fuel in the combustion chamber.

4. A 4-cylinder four stroke petrol engine develops 14.7 KW at 1000 r.p.m. The mean effective pressure is 5.5 bar. Calculate the bore and stroke of the engine, if the length of stroke is 1.5 times the bore.
a) 87.9 mm and 131.8 mm
b) 90 mm and 134 mm
c) 97.4 mm and 138 mm
d) none of the mentioned

View Answer

Answer: a [Reason:] Number of cylinder, n = 4 Power developed, P = 14.7 kW Engine speed, N = 1000 r.p.m. Indicated mean effective pressure, Pmi = 5.5 bar Length of stroke, L = 1.5D (bore) For four stroke cycle, k = 1/2

Indicated power developed, I.P. = (nPmiLANk x 10)/6 kw 14.7 = (4 x 5.5 x 1.5D x (pi/4 x D2)x 1000 x 1/2 x 10)/6 therefore, D3 = 0.0006806 or, D = 0.0879 or 87.9 mm and L = 1.5 x 87.9 = 131.8 mm.

5. A single cylinder, four stroke cycle oil engine is fitted with a rope brake. The diameter of the brake wheel is 600 mm and the rope diameter is 26 mm. The dead load on the brake is 200 N and the spring balance reads 30 N. If the engine runs at 450 r.p.m., what will be the brake power of the engine?
a) 2 kW
b) 2.5 kW
c) 3 kW
d) 3.5 kW

View Answer

Answer: b [Reason:] Diameter of the brake wheel, Db = 600 mm = 0.6 m Rope diameter, d = 26 mm = 0.026 m Dead load on the brake, W = 200 N Spring balance reading, S = 30 N Engine speed, N = 450 r.p.m. Brake Power, B.P. = ((W – S)pi(Db + d)N)/60 x 1000 = ((200 – 30)pi(0.6 + 0.026) x 450)/60 x 1000 = 2.5 kW.

6. The brake output per unit of piston displacement is defined as brake power.
a) True
b) False

View Answer

Answer: b [Reason:] The brake output per unit of piston displacement is defined as specific output.

7. Types of absorption dynamo meters are
a) prony brake
b) rope brake
c) hydraulic brake
d) all of the mentioned

View Answer

Answer: d [Reason:] Common forms of absorption dynamo meters are : a) prony brake b) rope brake c) hydraulic brake d) fan brake e) electrical brake dynamo meters.

8. Transmission dynamo meters are also known as
a) rope brake
b) hydraulic brake
c) torque meters
d) none of the mentioned

View Answer

Answer: c [Reason:] Transmission dynamo meters are also known as torque meters while rope brake and hydraulic brake are types of absorption dynamo meters.

9. The brake power is the power available
a) in the engine cylinder
b) at the crank shaft
c) at the crank pin
d) none of the mentioned

View Answer

Answer: b [Reason:] The power developed by an engine at the output shaft and it is only available at the crank shaft.

10. The frictional power (F.P) is given by
a) F.P. = B.P.-I.P.
b) F.P. = I.P.-B.P.
c) F.P. = B.P./I.P.
d) F.P. = I.P./B.P.

View Answer

Answer: b [Reason:] The frictional power is the difference between indicated power and brake power. So Mathematically, F.P = I.P.-B.P.

Set 5

1.The air fuel ratio of the petrol engine is controlled by
a) fuel pump
b) governor
c) injector
d) carburettor

View Answer

Answer: d [Reason:] The air fuel ratio of the petrol engine is controlled by carburettor and not by injector or fuel pump.

2. Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads
a) the friction is high
b) the friction is unpredictable
c) the small difference in cooling water temperature or in internal friction has a disproportionate effect
d) the engine is rarely operated

View Answer

Answer: c

3. The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be
a) higher
b) lower
c) remain unaffected
d) none of the mentioned

View Answer

Answer: a

4. The theoretically correct air fuel ratio for petrol engine is of the order of
a) 6:1
b) 9:1
c) 12:1
d) 15:1

View Answer

Answer: d

5. Air fuel ratio for idling speed of a petrol engine is approximately
a) 1:1
b) 5:1
c) 10:1
d) 15:1

View Answer

Answer: c

6. Air fuel ratio at which a petrol engine can not work is
a) 8:1
b) 10:1
c) 15:1
d) 20:1 and less

View Answer

Answer: d

7. For maximum power generation, the air fuel ratio for a petrol engine of vehicles, is of the order of
a) 9:1
b) 12:1
c) 15:1
d) 18:1

View Answer

Answer: b

8. The following volume of air is required for consuming 1 litre of fuel by a four stroke engine
a) 1m3
b) 2.5m3
c) 5-6m3
d) 9-10m3

View Answer

Answer: d [Reason:] 9-10m3 volume of air is required for consuming 1 litre of fuel by a four stroke engine.

9. Diesel engine can work on very lean air fuel ratio of the order of 30:1. A petrol engine can also work on such a lean ratio provided
a) it is properly designed
b) best quality fuel is used
c) can not work as it is impossible
d) flywheel size is proper

View Answer

Answer: c [Reason:] Petrol engine cannot work below air fuel ratio 20:1.

10. A stoichiometric air fuel ratio is
a) chemically correct mixture
b) lean mixture
c) rich mixture for idling
d) rich mixture for over loads

View Answer

Answer: a