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# Multiple choice question for engineering

## Set 1

1. Rankine cycle efficiency of a good steam power plant may be in the range of
a) 15 to 20%
b) 35 to 45%
c) 70 to 80%
d) 90 to 95%

Answer: b [Reason:] The efficiency of a Rankine cycle lies in the range of 35-45 percent mostly.

2. Rankine cycle operating on low pressure limit of p1 and high pressure limit of p2
a) has higher thermal efficiency than the Carnot cycle operating between same pressure limits
b) has lower thermal efficiency than Carnot cycle operating between same pressure limits
c) has same thermal efficiency as Carnot cycle operating between same pressure limits
d) may be more or less depending upon the magnitudes of p1 and p2

Answer: a [Reason:] For two pressure limits, the thermal efficiency of a Rankine cycle is more than that of the Carnot cycle operating between the same pressure difference which is evident in the P-V diagrams of both the cycle.

3. Rankine efficiency of a steam power plant
a) improves in summer as compared to that in winter
b) improves in winter as compared to that in summer
c) is unaffected by climatic conditions
d) none of the mentioned

Answer: b [Reason:] Rankine cycle efficiency depends upon condenser temperature.

4. Rankine cycle comprises of
a) two isentropic processes and two constant volume processes
b) two isentropic processes and two constant pressure processes
c) two isothermal processes and two constant pressure processes
d) none of the mentioned

Answer: b [Reason:] A rankine cycle is a thermodynamic cycle which comprises of two isentropic and two isobaric processes which is a major thermodynamic cycle in various applications.

5. In Rankine cycle the work output from the turbine is given by
a) change of internal energy between inlet and outlet
b) change of enthalpy between inlet and outlet
c) change of entropy between inlet and outlet
d) change of temperature between inlet and outlet

Answer: b [Reason:] The power output from the turbine is given by the change of internal energy between inlet and outlet.

6. Regenerative heating i.e., bleeding steam to reheat feed water to boiler
a) decreases thermal efficiency of the cycle
b) increases thermal efficiency of the cycle
c) does not affect thermal efficiency of the cycle
d) may increase or decrease thermal efficiency of the cycle depending upon the point of extraction of steam

Answer: b [Reason:] Bleeding decreases the thermal efficiency of the cycle as it reheats feed water to the boiler.

7. Regenerative cycle thermal efficiency
a) is always greater than simple Rankine thermal efficiency
b) is greater than simple Rankine cycle thermal efficiency only when steam is bled at particular pressure
c) is same as simple Rankine cycle thermal efficiency
d) is always less than simple Rankine cycle thermal efficiency

Answer: a [Reason:] A regeneration is done to increase the efficiency of a reheat cycle so naturally the efficiency of a regenerative cycle is much more than a Rankine cycle.

8. In a regenerative feed heating cycle, the optimum value of the fraction of steam extracted for feed heating
a) decreases with increase in Rankine cycle efficiency
b) increases with increase in Rankine cycle efficiency
c) is unaffected by increase in Rankine cycle efficiency
d) none of the mentioned

Answer: b [Reason:] In case of regenerative feed heating cycle, the optimum value of the fraction of steam extracted for feed heating decreases with increase in Rankine cycle efficiency. As the efficiency of regenerative cycle is more than the Rankine cycle.

9. In a regenerative feed heating cycle, the greatest economy is affected
a) when steam is extracted from only one suitable point of steam turbine
b) when steam is extracted from several places in different stages of steam turbine
c) when steam is extracted only from the last stage of steam turbine
d) when steam is extracted only from the first stage of steam turbine

Answer: b [Reason:] Steam extraction is an important factor in deciding the economy of a regenerative cycle. The greatest economy is affected when steam is extracted from several places in different stages of steam turbine.

10. The maximum percentage gain in Regenerative feed heating cycle thermal efficiency
a) increases with number of feed heaters increasing
b) decreases with number of feed heaters increasing
c) remains same unaffected by number of feed heaters
d) none of the mentioned

Answer: a [Reason:] In case of regenerative feed heating cycle, the optimum value of the fraction of steam extracted for feed heating decreases with increase in Rankine cycle efficiency. As the efficiency of regenerative cycle is more than the Rankine cycle. Naturally, the maximum percentage gain in regenerative feed heating cycle thermal efficiency increases with number of feed heaters increasing.

## Set 2

1. Which of the following type heater is known as deaerator?
a) Contact-type open heater
b) Contact-type closed heater
c) Closed heater
d) None of the mentioned

Answer: a [Reason:] A deaerator is a closed-type open feedwater heater while all the other heaters are closed heaters.

2. What is the solubility of dissolved gases at boiling or saturation temperature?
a) Positive
b) Negative
c) Zero
d) None of the mentioned

Answer: c [Reason:] The solubility of dissolved gases in water decreases with an increase in pressure and becomes zero at boiling or saturation temperature.

3. In the deaerator, the feedwater is heated to the saturation temperature by the steam extracted from?
a) compressor
b) turbine
c) pump
d) none of the mentioned

Answer: b [Reason:] The steam extracted from the turbine is used to heat the feedwater to the saturation temperature.

4. The heat exchanger after passing through which, the feedwater is sprayed from the top is called?
a) Vent condenser
b) Vent evaporator
c) Vent economiser
d) Vent heater

Answer: a [Reason:] Feedwater after passing through a heat exchanger, is sprayed from the top & bled steam from the turbine is fed from the bottom.

5. What kind of steam comes through the other side of the feedwater spray?
a) pure steam
b) bled steam
c) saturated steam
d) superheated steam

Answer: b [Reason:] Feedwater after passing through a heat exchanger, is sprayed from the top & bled steam from the turbine is fed from the bottom.

6. The chemical injected into the feedwater at the suction of the boiler feed pump is ?
a) Sodium Sulphide
b) Sodium Sulphate
c) Sodium Sulphite
d) Sodium Hydride

Answer: c [Reason:] To minimise the effect of the residual dissolved oxygen & carbon dioxide gases in water, Sodium Sulphite & Hydrazine are injected in suitable calculated doses into the feedwater at the suction of the boiler feed pump.

7. Why is Sodium Sulphite added into the feedwater at the suction of the boiler feed pump?
a) to maximise the effect of dissolved gases
b) to minimise the effect of dissolved gases
c) to increase feedwater concentration
d) none of the mentioned

Answer: b [Reason:] To minimise the effect of the residual dissolved oxygen & carbon dioxide gases in water, Sodium Sulphite & Hydrazine are injected in suitable calculated doses into the feedwater at the suction of the boiler feed pump.

8. Name another chemical apart from Sodium Sulphite which is into the feedwater at the suction of the boiler feed pump?
a) Calcium peroxide
b) Hydroxide
c) Hydrazine
d) Oxymes

Answer: c [Reason:] To minimise the effect of the residual dissolved oxygen & carbon dioxide gases in water, Sodium Sulphite & Hydrazine are injected in suitable calculated doses into the feedwater at the suction of the boiler feed pump.

9. Where is the deaerator placed in the feedwater system?
a) in the beginning
b) in the middle
c) at the end
d) there is no deaerator in the feedwater system

Answer: b [Reason:] The deaerator is usually placed in the middle of the feedwater system so that the total pressure difference between the condenser & the boiler is shared equally between condensate pump & boiler feed pump.

10. Why is the deaerator placement in the feedwater system so important?
a) to maximise pressure difference between the condenser & the boiler
b) to minimise pressure difference between the condenser & the boiler
c) to make the pressure difference between the condenser & the boiler Zero
d) none of the mentioned

Answer: c [Reason:] The deaerator is usually placed in the middle of the feedwater system so that the total pressure difference between the condenser & the boiler is shared equally between condensate pump & boiler feed pump.

11. Which gases are vented out of the deaerator?
a) Oxygen only
b) Carbon dioxide only
c) Oxygen & Carbon dioxide both
d) None of the mentioned

Answer: c [Reason:] The exhaust of the feedwater deaerator contains Oxygen & Carbon dioxide both.

12. Net positive suction head(NPSH) is provided because?
a) to prevent vapour lock
b) to prevent cavitation
c) to prevent friction
d) none of the mentioned

Answer: b [Reason:] In order to prevent the cavitation arising, a net positive suction head is provided for the pump. The deaerator is placed at a sufficient height from the basement.

13. The output of the boiler heat pump is to?
a) the high pressure heater
b) the low pressure heater
c) simultaneously to the low & high pressure heaters
d) none of the mentioned

Answer: a [Reason:] The Boiler feed pump give an output which goes to the high pressure heater.

14. Why is the deaerator not employed in water cooled & moderated nuclear power plant?
a) due to radioactivity release in degeneration
b) due to emissivity of degeneration
c) due to reheating
d) due to regeneration

Answer: a [Reason:] The deaerator is not employed in water cooled & moderated nuclear power plant because of the radioactivity released in degeneration.

15. Which among the following goes to the Vent Condenser along with Oxygen & Carbon dioxide?
a) Sodium sulphite
b) Carbon monoxide
c) Water vapour
d) None of the mentioned

Answer: c [Reason:] The gases Oxygen, Carbon dioxide & Water vapour are subjected to the vent condenser wherein the moisture gets absorbed & so the exhaust gases vented out are Oxygen & Carbon dioxide.

## Set 3

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

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

2. The control rods in the control system of nuclear reactors are used to
a) control fuel consumption
b) absorb excess neutrons
c) control temperature
d) all of the mentioned

Answer: b [Reason:] The function of control rods is to absorb the excess neutrons released during fission.

3. The pressure at the end of compression, in petrol engines, is approximately
a) 10 bar
b) 20 bar
c) 25 bar
d) 35 bar

Answer: a [Reason:] The pressure at the end of compression, in petrol engines, is approximately 10 bar.

4. If the speed of the engine is increased, the indicated power will
a) increase
b) decrease
c) remain same
d) none of the mentioned

Answer: a [Reason:] The speed of the engine & indicated power are inter related as they are directly proportional to each other, so if one increases, the other also increases & vice-versa.

5. Number of working strokes per min. for a two stroke cycle engine are __________ the speed of the engine in r.p.m.
a) equal to
b) one-half
c) four-times
d) twice

Answer: a [Reason:] Number of working strokes per min. for a two stroke cycle engine are equal to the speed of the engine in rpm.

6. Reflector in nuclear power plants __________ neutron leakage.
a) increases
b) decreases
c) has no effect
d) all of the mentioned

Answer: b [Reason:] Reflector in nuclear power plants decreases neutron leakage.

7. In order to eliminate knocking in compression ignition engines, there should be
a) high self-ignition temperature of fuel
b) late auto-ignition
c) short delay period
d) low compression ratio

Answer: c [Reason:] In order to eliminate knocking in compression ignition engines, there should be a shorter delay period.

8. Which of the following statement is correct?
a) Compression ratio for petrol engines varies from 6 to 10
b) Petrol engines work on Otto cycle
c) Higher compression ratio in diesel engines results in higher pressures
d) All of the mentioned

Answer: d [Reason:] All the mentioned statements are correct.

9. The injector nozzle of a compression ignition engine is required to inject fuel at a sufficiently high pressure in order to
a) inject fuel at a high velocity to facilitate atomisation
b) inject fuel in a chamber of high pressure at the end of compression stroke
c) ensure that penetration is not high
d) all of the mentioned

Answer: d [Reason:] The fuel injection is at a sufficiently higher pressure in order to inject fuel at a high velocity to facilitate atomisation, to inject fuel in a chamber of high pressure at the end of compression stroke & to ensure that penetration is not high.

10. The two reference fuels used for cetane rating are
a) cetane & iso-octane
b) cetane & normal heptane
c) cetane & alpha methyl naphthalene
d) cetane & tetra ethyl lead

Answer: c [Reason:] Cetane & alpha methyl naphthalene are the two reference fuels used for cetane rating.

11. In petrol engines, the delay period is of the order of
a) 0.001 sec
b) 0.002 sec
c) 0.003 sec
d) 0.004 sec

Answer: b [Reason:] The delay period in petrol engines is of the order of 0.002 sec.

12. The voltage required to produce a spark across the gap, between the sparking points is
a) 2000-4000 volts
b) 4000-6000 volts
c) 6000-10000 volts
d) 10000-12000 volts

Answer: c [Reason:] The voltage required to produce a spark across the gap, between the sparking points is 6000-10000 Volts.

13. The scavenging efficiency of a tour stroke cycle diesel engine is
a) between 50-85%
b) between 95-100%
c) below 50%
d) between 85-95%

Answer: b [Reason:] The scavenging efficiency of a tour stroke cycle diesel engine is between 95-100%.

14. The specific fuel consumption per B.P. hour for a petrol engine is about
a) 0.2 kg
b) 0.25 kg
c) 0.3 kg
d) 0.35 kg

Answer: b [Reason:] The brake specific fuel consumption for a petrol engine is about 0.25 kg.

15. The material most commonly used for shielding is
a) Carbon
b) Concrete
d) All of the mentioned

Answer: c [Reason:] Lead is the material that is most commonly used for Shielding.

## Set 4

1. If the temperature of intake air in internal combustion engine increases, then its efficiency will
a) remain same
b) increase
c) decrease
d) none of the mentioned

Answer: c [Reason:] The efficiency of an IC Engine is inversely proportional to the temperature of intake air.

2. The operation of forcing additional air under pressure in the engine cylinder is known as
a) Supercharging
b) Scavenging
c) Turbulence
d) Pre-ignition

Answer: a [Reason:] Supercharging is the operation of forcing additional air under pressure in the engine cylinder.

3. The ignition quality of petrol is expressed by
a) Cetane number
b) Octane number
c) Calorific Value
d) None of the mentioned

Answer: b [Reason:] Octane number estimates the quality of petrol.

4. The mean effective pressure obtained from engine indicator indicates the
a) maximum pressure developed
b) minimum pressure developed
c) Instantaneous pressure at any point
d) Average pressure

Answer: d [Reason:] The mean effective pressure indicates the average pressure on the engine.

5. The probability of knocking in diesel engines is increased by
a) high self-ignition temperature
b) low volatility
c) high viscosity
d) all the mentioned

Answer: d [Reason:] The probability of knocking in diesel engines is increased by keeping high self-ignition temperature, low volatility, high viscosity, etc.

6. Reactors for propulsion applications are designed for
a) any form of uranium
b) natura uranium
c) enriched uranium
d) thorium

Answer: c [Reason:] Enriched uranium is the material that is used for making reactors for propulsion application.

7. Pour point of fuel oil is the
a) Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
b) Temperature at which it solidifies or congeals
c) It catches fire without external aid
d) Indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off

Answer: b [Reason:] The temperature at which fuel oil solidifies or congeals is called pour point of fuel oil.

8. The maximum temperature in the I.C. engine cylinder is of the order of(in degree Celsius)
a) 500-1000
b) 1000-1500
c) 1500-2000
d) 2000-2500

Answer: d [Reason:] The maximum temperature in the I.C. engine cylinder is of the order of(in degree Celsius) is 2000-25000 degree Celsius.

9. In compression ignition engines, swirl denotes a
a) Haphazard motion of the gases in the chamber
b) Rotary motion of the gases in the chamber
c) Radial motion of the gases in the chamber
d) None of the mentioned

Answer: b [Reason:] Swirl in a compression ignition engine denotes rotary motion of the gases in the chamber.

10. Supercharging is the process of
a) Supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere
b) Supplying compressed air to remove combustion products fully
c) Providing excess temperature to the sucked in gases
d) None of the mentioned

Answer: a [Reason:] Supercharging is the process of supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere.

11. The object of supercharging the engine is
a) to increase the power output of an engine when greater power is required
b) to reduce mass of the engine per brake power
c) to reduce space occupied by the engine
d) all of the mentioned

Answer: d [Reason:] Supercharging is done to increase the power output of an engine, to reduce mass of the engine per brake power & to reduce space occupied by the engine.

12. The compensating jet in a carburettor 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) flow is produced due to the static head in the float chamber
d) the diameter of the jet is constant and the discharge coefficient is invariant

Answer: c [Reason:] The compensating jet in a carburettor supplies almost constant amount of petrol at all speeds because the flow is produced due to the static head in the float chamber.

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

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.

14. A moderator generally used in nuclear power plants is
a) heavy water
b) concrete
c) graphite & concrete
d) graphite

Answer: c [Reason:] A moderator generally used in nuclear power plants is made up of graphite & concrete.

15. In a diesel engine, the duration between the time of injection and ignition, is known as
a) delay period
b) period of ignition
c) burning period
d) pre-ignition period

Answer: a [Reason:] In a diesel engine, the duration between the time of injection and ignition, is known as delay period.

## Set 5

1. Nuclear Reactors are used
a) to produce heat for thermoelectric power
b) to propel ships, submarines, aircrafts
c) to produce fissionable material
d) all of the mentioned

Answer: d [Reason:] Nuclear reactors have wide range of usage which include producing heat for thermoelectric power, ship propulsion, production of fissionable materials, etc.

2. Where reactor operation is designed with fast neutrons such as in reactors using highly enriched fuel, the moderator used is
a) Carbon dioxide
b) Heavy Water
c) Graphite
d) No moderator is needed

Answer: d [Reason:] Where reactor operation is designed with fast neutrons such as in reactors using highly enriched fuel, no moderator is required.

3. The expansion of fuel in a four stroke cycle diesel engine
a) starts at 15° after top dead centre and ends at 30° before bottom dead centre
b) starts at top dead centre and ends at 30° after top dead centre
c) may start and end anywhere
d) starts at 15° before top dead centre and ends at 30° after top dead centre

Answer: a [Reason:] The expansion of fuel in a four stroke cycle diesel engine starts at 15° after top dead centre and ends at 30° before bottom dead centre.

4. A moderator, in nuclear power plants, is a medium introduced into the fuel mass in order to
a) slow down the speed of fast moving neutrons
b) control the reaction
c) reduce the temperature
d) extract heat from nuclear reaction

Answer: a [Reason:] A moderator, in nuclear power plants, is a medium introduced into the fuel mass in order to slow down the speed of fast moving neutrons.

5. The thermal efficiency of diesel engines is about
a) 30%
b) 15%
c) 50%
d) 70%

Answer: d [Reason:] The thermal efficiency of diesel engines is about 70%.

6. In a four stroke cycle petrol engine, the charge is ignited at
a) 30° after bottom dead centre
b) 30° before bottom dead centre
c) 30° after top dead centre
d) 30° before top dead centre

Answer: d [Reason:] In a four stroke cycle petrol engine, the charge is ignited at 30° before top dead centre.

7. The exhaust valve in a four stroke cycle petrol engine
a) opens at 50° after bottom dead centre and closes at 15° before top dead centre
b) opens at 50° before bottom dead centre and closes at 15° after top dead centre
c) opens at bottom dead centre and closes at top dead centre
d) may open and close anywhere

Answer: b [Reason:] The exhaust valve in a four stroke cycle petrol engine opens at 50° before bottom dead centre and closes at 15° after top dead centre.

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

Answer: a [Reason:] The brake power of a diesel engine, keeping other parameters constant, can be increased by increasing the pressure of intake air.

9. In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the
a) end of suction stroke
b) beginning of exhaust stroke
c) beginning of suction stroke
d) end of exhaust stroke

Answer: c [Reason:] In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the beginning of exhaust stroke.

10. The effective inhibitor of pre-ignition is
a) alcohol