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# Multiple choice question for engineering

## Set 1

1. The ratio of the work done on the blades to the energy supplied to the blades, is called
a) gross or stage efficiency
c) nozzle efficiency
d) mechanical efficiency

Answer: b [Reason:] Blading Efficiency is the ratio of work done on the blades to the energy supplied to the blades of a turbine.

2. A nozzle is said to be a convergent nozzle
a) when the cross-section of the nozzle increases continuously from entrance to exit
b) when the cross-section of the nozzle decreases continuously from entrance to exit
c) when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
d) none of the mentioned

Answer: b [Reason:] In case of a convergent nozzle, the cross-section of the nozzle decreases continuously from entrance to exit.

3. Multi-stage steam turbines are of the
a) reaction type
b) velocity compounded type
c) pressure compounded type
d) all the mentioned

Answer: d [Reason:] There are various types of multi-stage steam turbines which are, reaction; velocity compounded; & pressure compounded, respectively.

4. The impulse reaction turbine has its driving force
a) partly as an impulsive force and partly as a reaction force
b) as an impulsive force
c) as a reaction force
d) none of the mentioned

Answer: a [Reason:] The impulse reaction turbine has its driving force partly as an impulsive force & partly as a reaction force as the components add to the resultant.

5. In a nozzle, whole frictional loss is assumed to occur between
a) inlet and throat
b) throat and exit
c) inlet and outlet
d) none of the mentioned

Answer: b [Reason:] In a nozzle, whole frictional loss is assumed to occur between the throat & exit of the nozzle.

6. The ratio of total useful heat drop to the total isentropic heat drop, is called
a) Rankine efficiency
b) Stage efficiency
c) Internal efficiency
d) None of the mentioned

Answer: c [Reason:] The ratio of total useful heat drop to the total isentropic heat drop is called internal efficiency.

7. The action of steam in a steam turbine is
a) neither static nor dynamic
b) dynamic
c) static
d) both dynamic & static

Answer: b [Reason:] Steam action in a steam turbine is Dynamic.

8. The critical pressure gives the velocity of steam at the throat
a) equal to the velocity of sound
b) more than velocity of sound
c) less than the velocity of light
d) none of the mentioned

Answer: a [Reason:] The critical pressure gives the velocity of steam at the throat which is equal to the velocity of sound.

9. The isentropic enthalpy drop in moving blade is two-third of the isentropic enthalpy drop in fixed blades of a turbine. The degree of reaction will be
a) 0.67
b) 0.4
c) 0.5
d) 0.56

Answer: a [Reason:] The required degree of reaction will be 0.67.

10. The flow through a nozzle is regarded as
a) isothermal flow
b) isobaric flow
c) isochoric flow
d) isentropic flow

Answer: d [Reason:] The flow through a nozzle is regarded as isentropic flow.

## Set 2

1. What is the harm from the depletion of Earth’s ozone layer?
a) The average temperature of earth’s surface will increase gradually
b) The oxygen content of the atmosphere will decrease
c) Increased amount of Ultra violet radiation will reach earth’s surface
d) Sea levels will rise as the polar ice caps will gradually melt

Answer: c [Reason:] The decrease in the oxygen content of the atmosphere is the only harm from the depletion of Earth’s Ozone Layer.

2. Acid rain is formed due to contribution from the following pair of gases
a) Methane and ozone
b) Oxygen and nitrous oxide
c) Methane and sulphur dioxide
d) Carbon dioxide and sulphur dioxide

Answer: b [Reason:] Acid rain is formed due to contribution of Methane & Sulphur dioxide.

3. Which of the following is a prime health risks associated with greater UV radiation through the atmosphere due to depletion of stratospheric ozone?
a) Damage to digestive system
b) Increased liver cancer
c) Neurological disorder
d) Increased skin cancer

Answer: d [Reason:] Increased risk of Skin Cancer is the prime health risks associated with greater UV radiation through the atmosphere due to depletion of stratospheric ozone.

4. The most serious environmental effect posed by hazardous wastes is
a) air pollution
b) contamination of groundwater
c) increased use of land for landfills
d) destruction of habitat

Answer: b [Reason:] The most serious environmental effect posed by hazardous wastes is contamination of groundwater.

5. The concentration of which gas is highest in our environment?
a) Oxygen
b) Hydrogen
c) Nitrogen
d) Carbon dioxide

Answer: c [Reason:] Nitrogen has the highest concentration in the environment constituting about 71% of the environmental gases.

6. Which of the following is not as a consequence of global warming?
a) rising sea level
b) increased agricultural productivity worldwide
c) worsening health effects
d) increased storm frequency and intensity

Answer: b [Reason:] Increased agricultural productivity is not a consequence of global warming.

7. Which of the following is not a primary contributor to the greenhouse effect?
a) carbon dioxide
b) carbon monoxide
c) chlorofluorocarbons
d) methane gas

Answer: c [Reason:] CFC’s aren’t a primary contributor to the greenhouse effect.

8. The increase in the concentration of CO2 in our environment in last fifty years; since 1960 is about
a) 20%
b) 10%
c) 14%
d) 6%

Answer: c [Reason:] The increase in the concentration of CO2 in our environment in last fifty years; since 1960 is about 14%.

9. The depletion in the Ozone layer is caused by
a) nitrous oxide
b) carbon dioxide
c) chlorofluorocarbons
d) methane

Answer: c [Reason:] The depletion in the Ozone layer is caused by Chlorofluorocarbons.

10. A major in-stream use of water is for
a) producing hydroelectric power
b) dissolving industrial wastes
c) agricultural irrigation
d) domestic use

Answer: a [Reason:] Production of hydroelectric power is a major in-stream use of water.

## Set 3

1. When the circulation of water, in a boiler, is by a centrifugal pump, then the boiler is known as
a) forced circulation boiler
b) externally fired boiler
c) naturally circulation boiler
d) internally fired boiler

Answer: a [Reason:] When the circulation of water, in a boiler, is by a centrifugal pump, then the boiler is known as forced circulation boiler.

2. A single acting steam engine produces __________ power than that of double acting steam engine
a) equal
b) double
c) half
d) 4 times

Answer: c [Reason:] A single acting steam engine produces half power than that of double acting steam engine.

3. Cut-off governing of steam engines is a method of controlling the engine output by varying
a) volume of intake steam
b) pressure of intake steam
c) temperature of intake steam
d) all of the mentioned

Answer: a [Reason:] Cut-off governing of steam engines is a method of controlling the engine output by varying volume of intake steam.

4. A device in which some portion of waste heat of flue gases is recovered to heat the air before it passes to the furnace for combustion purpose, is known as
a) air preheater
b) superheater
c) injector
d) none of the mentioned

Answer: a [Reason:] A device in which some portion of waste heat of flue gases is recovered to heat the air before it passes to the furnace for combustion purpose, is knwon as air-preheater.

5. Which of the following statement is correct?
a) Fire tube boilers are internally fired
b) Lancashire boiler is a fire tube boiler
c) Babcock and Wilcox boiler is a water tube boiler
d) All the mentioned

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

6. In a uniflow engine
a) steam enters and exhausts through the same port
b) steam enters at one end and exhausts at the centre
c) steam enters at the centre and exhausts at the other end
d) none of the mentioned

Answer: b [Reason:] Steam enters at one end and exhausts at the centre in a Uniflow engine.

7. A safety valve mainly used with locomotive and marine boilers is
a) lever safety valve
d) high steam and low water safety valve

Answer: c [Reason:] A safety valve mainly used with locomotive and marine boilers is spring loaded safety valve.

8. The power of a boiler may be defined as
a) the amount of water evaporated or steam produced in kg per kg of fuel burnt
b) the ratio of heat actually used in producing the steam to the heat liberated in the furnace
c) the evaporation of 15.653 kg of water per hour from and at 100° C
d) the amount of water evaporated from and at 100° C into dry and saturated steam

Answer: a [Reason:] The power of a boiler may be defined as the amount of water evaporated or steam produced in kg per kg of fuel burnt.

9. Which of the following boiler is best suited to meet the fluctuating demand of steam?
a) Cornish boiler
b) Lancashire boiler
c) Locomotive boiler
d) Babcock & Wilcox boiler

Answer: c [Reason:] Locomotive Boiler is the best suited to meet the fluctuating demand of steam.

10. The diameter of Cornish boiler varies from
a) 1 to 2m
b) 0.5 to 1m
c) 1.25 to 2.5m
d) 2 to 3m

Answer: a [Reason:] The diameter of Cornish Boiler varies from 1-2 m.

11. Besides mean effective pressure, the data required to determine the indicated power of an engine include
a) piston diameter, length of stroke and calorific value of fuel
b) piston diameter, specific fuel consumption and Calorific value of fuel
c) piston diameter, length of stroke and speed of rotation
d) specific fuel consumption, speed of rotation and torque

Answer: c [Reason:] Besides mean effective pressure, the data required to determine the indicated power of an engine include piston diameter, length of stroke and speed of rotation.

12. A compound steam engine in which the high pressure and low pressure cylinders have common piston rod, is called
a) Tandem type compound engine
b) Woolf type compound engine
d) None of the mentioned

Answer: a [Reason:] A compound steam engine in which the high pressure and low pressure cylinders have common piston rod, is called Tandem type compound engine.

13. The average operating pressure of Benson boiler is
a) 200 bar
b) 150 bar
c) 250 bar
d) 100 bar

Answer: b [Reason:] The average operating pressure of Benson boiler is 150 bar.

14. The function of a safety valve is
a) to indicate the water level inside the boiler to an observer
b) to measure pressure of steam inside the steam boiler
c) to blow off steam when the pressure of steam inside the boiler exceeds the working pressure
d) none of the mentioned

Answer: c [Reason:] The function of a safety valve is to blow off steam when the pressure of steam inside the boiler exceeds the working pressure.

15. The rate of steam produced in Benson boiler is
a) 250 tonnes/h
b) 175 tonnes/h
c) 100 tonnes/h
d) 135 tonnes/h

Answer: d [Reason:] The rate of steam produced in Benson boiler is 135 tonnes/h.

## Set 4

1. In gas turbine, intercooler is placed
a) before low pressure compressor
b) in between low pressure compressor and high pressure compressor
c) in between high pressure compressor and turbine
d) None of the mentioned

Answer: b [Reason:] The various methods to improve the efficiency of open cycles include intercooling the feed water from the compressor to the turbine and then employing regeneration & reheat to just use the power of the reheated water in order to maximize the power output. Here, this is done by placing the intercooler before any of the above processes.

2. In gas turbine, the function of Re-heater is to
a) Heat inlet air
b) Heat exhaust gases
c) Heat air coming out of compressor
d) Heat gases coming out of high pressure turbine

Answer: d [Reason:] In order to make a thermodynamic process of larger efficiency, it is shifted towards isothermal behavior. For this, the output from re-generator, which is at a higher temperature is cooled to the temperature which is mid-way between the two temperature ranges. Then, it is again heated to the final temperature thereby increasing the efficiency of the cycle.

3. The ‘work ratio’ increases with
a) increase in turbine inlet pressure
b) decrease in compressor inlet temperature
c) decrease in pressure ratio of the cycle
d) all of the mentioned

Answer: d [Reason:] The ‘work ratio’ increases when the turbine inlet pressure increases, the compressor inlet temperature decreases, the pressure ratio of the cycle decreases.

4. In the centrifugal compressor, total pressure varies
a) directly as the speed ratio
b) square of speed ratio
c) cube of the speed ratio
d) any of the mentioned

Answer: b [Reason:] The total pressure in a centrifugal compressor is a function of speed ratio. It varies square of the speed ratio.

5. The efficiency of multistage compressor is _____ than a single stage.
a) lower
b) higher
c) equal to
d) any of the mentioned

Answer: a [Reason:] The efficiency of multistage compressor is lower than a single stage.

6. In centrifugal compressor, power input varies as
a) directly as the speed ratio
b) the square of speed ratio
c) the cube of the speed ratio
d) any of the mentioned

Answer: c [Reason:] Power output in a centrifugal compressor varies as the cube of the speed ratio.

7. In the _____ heat transfer takes place between the exhaust gases and cool air.
a) Intercooler
b) Re-heater
c) Regenerator
d) Compressor

Answer: c [Reason:] The process of heat transfer between the exhaust gases and cool air takes place in Regenerator.

8. In centrifugal compressor, the diffuser converts
a) Kinetic energy into pressure energy
b) Pressure energy into Kinetic energy
c) Kinetic energy into Mechanical energy
d) Mechanical energy into Kinetic energy

Answer: a [Reason:] The diffuser of a centrifugal compressor converts Kinetic Energy into Pressure energy.

## Set 5

1. Feed water heaters are of how many types?
a) One
b) Two
c) Three
d) Four

Answer: b [Reason:] There are two types of feed water heaters- 1) Open Heater 2) Closed Heater.

2. What is the other name of open heater?
a) shell & tube heat exchangers
b) contact type heaters
c) regenerative heat exchangers
d) closed heaters

Answer: b [Reason:] Open heaters are also known as contact type heaters where the extracted steam is allowed to mix with feedwater & both leave the heater at a common temperature.

3. What is the condition of the fluids in closed heaters?
a) they are separate
b) they are mixed
c) they are partially mixed
d) none of the mentioned

Answer: a [Reason:] The fluids in a closed heater are un-mixed or separated. Closed heaters are heat exchangers.

4. Closed heaters are ______________ heat exchangers.
a) parallel flow
b) shell-and-tube
c) counter flow
d) cross- flow

Answer: b [Reason:] Closed heaters are shell-and-tube heat exchangers where the feedwater flows through the tubes & the extracted steam condenses outside the walls in the shell. The heat released by condensation is transferred through the walls of the tubes.

5. What is the other name of the condensate obtained after condensation in a shell-and-tube heat exchanger type closed heaters?
a) Heater rise
b) Heater fall
c) Heater drip
d) none of the mentioned

Answer: c [Reason:] Closed heaters are shell-and-tube heat exchangers where the feedwater flows through the tubes & the extracted steam condenses outside the walls in the shell. The heat released by condensation is transferred through the walls of the tubes. The condensate sometimes called the heater drip then passes to the next lower level.

6. What is the function of the trap applied to the condensate?
a) the trap stops the condensate fully
b) the trap stops only vapour & allows liquid to pass through it
c) the trap stops only liquid & allows vapour to pass through it
d) none of the mentioned

Answer: b [Reason:] The main function of the trap applied to the flow of condensate is to stop vapour & allow liquid to flow through it.

7. Which of these is the correct expression for terminal temperature difference(TTD) ?
a) TTD = saturation temperature of ‘bled’ steam – exit water temperature
b) TTD = saturation temperature of ‘bled’ steam + exit water temperature
c) TTD = saturation temperature of ‘bled’ steam x exit water temperature
d) TTD = saturation temperature of ‘bled’ steam / exit water temperature

Answer: a [Reason:] The expression for terminal temperature difference for a closed heater is given as, TTD = saturation temperature of ‘bled’ steam – exit water temperature.

8. If terminal temperature difference (TTD) is too small, what will be its impact on plant efficiency?
a) it increases
b) it decreases
c) it remains same
d) none of mentioned

Answer: a [Reason:] The formula for TTD is given as, TTD = saturation temperature of ‘bled’ steam – exit water temperature.

9. If plant efficiency is high, what will be its effect on heater size?
a) it remains same
b) it increases
c) it decreases
d) none of the mentioned

Answer: b [Reason:] Too small a value of TTD, it is good for plant efficiency & consequently, tjis would require a larger heater.

10. When is a drain-cooler used?
a) when the extracted steam upon condensation gets subcooled
b) when the extracted steam upon subcooling gets condensed
c) the extracted stream has no dependence on drain-cooler
d) none of the mentioned

Answer: a [Reason:] When extracted steam gets subcooled upon condensation, a drain cooler may be used.

11. Which of these is a disadvantage of open heater?
a) simplicity
b) lower cost
c) high heat transfer capacity
d) none of the mentioned

Answer: d [Reason:] The disadvantage is the necessity of a pump at each heater to handle the large feedwater stream.

12. Which of the following is not an advantage of an open heater?
a) simplicity
b) lower cost
c) high heat transfer capacity
d) necessity of a pump at each heater to handle the large feedwater stream

Answer: d [Reason:] The disadvantage is the necessity of a pump at each heater to handle the large feedwater stream.

13. The number of pumps required by a closed heater for pumping the main feedwater stream is
a) 1
b) 2
c) 3
d) 4

Answer: a [Reason:] A closed heater requires only a single pump for the main feedwater stream regardless of the number of heaters.

14. What is the purpose of using open heaters in steam power plants?
a) feedwater purification
b) feedwater esterification
c) feedwater deaeration
d) feedwater carbonisation