Pak Navy Mechanical Engineering MCQs with Answers
Aspiring interested candidates for the prestigious Pak Navy Short Service Commission entry must recognize the critical importance of mastering the technical assessment, particularly the mechanical engineering segment. A thorough and strategic preparation method involves diligently practicing with complete Pak Navy mechanical engineering MCQs sourced from past papers of the initial tests. These collections of questions provide an invaluable insight into the exam’s format, the complexity of topics covered, and the recurring themes favored by the selection board.
If you want to join Pak Navy through Short Service Commission and you want to prepare initial tests of Pak Navy Mechanical Engineering MCQs then this is right place for you.
Most Important Past Papers of Pak Navy mechanical Engineering MCQs
Q: Petrol is distilled at a temperature range of _________.
(a) 6° to 20°
(b) 220° to 345°
(c) 65° to 220°
(d) 15° to 120°
Answer: (c) 65° to 220°
Q: _________ are commonly used in diesel engines and oil-fired boilers.
(a) Paraffin
(b) Gasoline
(c) Heavy fuel oils
(d) Petrol
Answer: (c) Heavy fuel oils
Q: Hydraulic turbines are also called _________.
(a) Steam turbines
(b) Water turbines
(c) Combustion turbines
(d) Gas turbines
Answer: (b) Water turbines
Q: For extracting pig iron in blast furnaces, the fuel mostly used is _________.
(a) Brown coal
(b) Anthracite coal
(c) Hard coke
(d) Woodchar coal
Answer: (c) Hard coke
Q: The solid fuel having the highest carbon content is _________.
(a) Coke
(b) Coal
(c) Peat
(d) None of these
Answer: (a) Coke
Q: The solid fuel with the highest caloric value is _________.
(a) Wood
(b) Peat
(c) Bituminous coal
(d) Anthracite coal
Answer: (d) Anthracite coal
Q: The average calorific value of wood is nearly _________.
(a) 33500 kj/kg
(b) 25000 kj/kg
(c) 23000 kj/kg
(d) 19700 kj/kg
Answer: (d) 19700 kj/kg
Q: The natural solid fuels include _________.
(a) Wood
(b) Peat
(c) Lignite
(d) All of above
Answer: (d) All of above
Q: For the same compression ratio, the efficiency of the Diesel cycle is _________ than that of the Otto cycle.
(a) Higher
(b) Lower
(c) Equal
(d) None of these
Answer: (a) Higher
Q: The Diesel cycle is also known as the _________.
(a) Constant temperature cycle
(b) Constant Volume cycle
(c) Constant Pressure Cycle
(d) All of above
Answer: (c) Constant Pressure Cycle
Q: The weight of one gallon of air at 1 atm and 25ËšC is about _________.
(a) 90 lbf
(b) 65.78 lbf
(c) 0.00989 lbf
(d) 3.00989 lbf
Answer: (c) 0.00989 lbf
Q: In the lever of third order, the orientation is such that _________.
(a) W between P and F
(b) F between W and P
(c) P between W and F
(d) W, P and F all on one side
(e) None of the above
Answer: (c) P between W and F
Q: Farad is the unit of _________.
(a) Inductance
(b) Voltage
(c) Capacitance
(d) None of these
Answer: (c) Capacitance
Q: Atmospheric pressure is equal to _________.
(a) 1.013 bar
(b) 760 mm of Hg
(c) 101.3 kN/m²
(d) All of these
Answer: (d) All of these
Q: The most common valve used in piping systems to throttle or regulate flow is _________.
(a) Globe valve
(b) Gate valve
(c) Butterfly valve
(d) Plug valve
Answer: (a) Globe valve
Q: Ball valves are commonly used to _________.
(a) Throttle flow
(b) Check flow
(c) Change flow direction
(d) Start/stop flow
Answer: (d) Start/stop flow
Q: The tool used to measure gap size in a rough alignment is _________.
(a) Inside caliper
(b) Dial indicator
(c) Feeler gage
(d) Measuring tape
Answer: (c) Feeler gage
Q: The part of the coupling that actually transmits power and rotation from one shaft to the other shaft is _________.
(a) Gap
(b) Hub
(c) Key
(d) Driver
Answer: (c) Key
Q: The stress developed in a material at breaking point in extension is called _________.
(a) Breaking stress
(b) Fracture stress
(c) Yield point stress
(d) Proof stress
Answer: (a) Breaking stress
Q: The incorrect statement about the effect of sulphur in fuel is that _________.
(a) It has heating value
(b) It helps in electrostatic precipitation of ash in flue gases
(c) It leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low
(d) It erodes furnace walls
(e) None of the above
Answer: (a) It has heating value
Q: The statement about moisture in coal that is not correct is that it _________.
(a) Inherent moisture and surface moisture are different things
(b) In some coals moisture may be present up to 40%
(c) Some moisture in coal helps in better burning which is not possible with completely dry coal
(d) It increases thermal efficiency
(e) Moisture in coal is removed before firing by heating it with hot air
Answer: (d) It increases thermal efficiency
Q: The statement about the function of furnace that is not correct is that it _________.
(a) Provides proper conditions for continuous complete combustion
(b) Mixes fuel with air and ignites
(c) Separates ash from coal
(d) Maintains heat supply to prepare and ignite the incoming fuel
(e) Minimises radiation losses
Answer: (c) Separates ash from coal
Q: The statement about pulverised fuel firing that is not correct is that it _________.
(a) High burning rate is possible
(b) Heat release can be easily controlled
(c) Fuel burns economically
(d) It is the best technique for burning high ash content fuel having low fusion ash
(e) Separate mills are required to powder the coal
Answer: (d) It is the best technique for burning high ash content fuel having low fusion ash
Q: The wrong statement about desired properties of a good fuel is that it should have _________.
(a) High calorific value
(b) Produce minimum smoke and gases
(c) Ease in storing
(d) High ignition point
(e) Be economical
Answer: (d) High ignition point
Q: The thermal efficiency of a thermal power plant is of the order of _________.
(a) 15%
(b) 20%
(c) 30%
(d) 45%
(e) 60%
Answer: (c) 30%
Q: The radius of a dished head is taken approximately as _________.
(a) One-fourth
(b) Half
(c) One
(d) Two
(e) Three
Answer: (d) Two
Q: The overall efficiency of a thermal power plant is _________.
(a) Boiler efficiency, turbine efficiency, generator efficiency
(b) All the three above plus gas cycle efficiency
(c) Carnot cycle efficiency
(d) Regenerative cycle efficiency
(e) Rankine cycle efficiency
Answer: (a) Boiler efficiency, turbine efficiency, generator efficiency
Q: In a forced circulation type boiler, _________.
(a) Heating takes place at the bottom and the water supplied at the bottom gets converted into steam-water mixture which rises to the drum
(b) Water is supplied in the drum and through down-comers located in atmospheric condition it passes to the water wall and rises in the form of steam-water mixture
(c) A feed pump is employed to supplement natural circulation in water wall type furnace
(d) Water is converted into steam in one pass without any recirculation
(e) Water is heated in a large number of tubes
Answer: (c) A feed pump is employed to supplement natural circulation in water wall type furnace
Q: The heat loss in a boiler takes place in the form of _________.
(a) Heat carried away by flue gases
(b) Heat carried away by ash
(c) Moisture present in fuel and steam formed by combustion of hydrogen in fuel
(d) Radiation
(e) All of the above
Answer: (e) All of the above
Q: The boiler in which the draught in the furnace is increased by utilising exhaust steam from the engine is the _________.
(a) Lancashire boiler
(b) Locomotive boiler
(c) Babcock and Wilcox boiler
(d) Cochran boiler
(e) Benson boiler
Answer: (b) Locomotive boiler
Free Practice of Pak Navy Mechanical Engineering MCQs with Answers
Related: How to Join Pak Navy Mechanical Branch through SSC?
Q: With increase in load, a convection superheater has _________.
(a) Drooping characteristic
(b) Linear characteristic
(c) Rising characteristic
(d) Flat characteristic
(e) None of the above
Answer: (a) Drooping characteristic
Q: In a recuperative air preheater, the heat is transferred _________.
(a) From a metal wall from one medium to another
(b) From heating an intermediate material and then heating the air from this material
(c) By direct mixing
(d) By bleeding some gases from furnace
(e) None of the above
Answer: (a) From a metal wall from one medium to another
Q: The temperature of flue gases at the air heater outlet should be _________.
(a) 100°C
(b) Above dew-point temperature of flue gases
(c) Below dew-point temperature of flue gases
(d) Less than wet bulb temperature of flue gases
(e) Above wet bulb temperature of flue gases
Answer: (b) Above dew-point temperature of flue gases
Q: In designing an air preheater, the important design consideration is that _________.
(a) Approach temperature should be as low as possible
(b) Handling and maintenance should be easier
(c) Heat transfer area should be optimum
(d) Stack gases should not be cooled to the dew point
(e) None of the above
Answer: (d) Stack gases should not be cooled to the dew point
Q: The function of an injector used in small capacity boilers is to _________.
(a) Create vacuum
(b) Inject chemical solution in feed pump
(c) Pump water, similar to boiler feed pump
(d) Add make up water in the system
(e) None of the above
Answer: (c) Pump water, similar to boiler feed pump
Q: The height of a chimney in a power plant is governed by _________.
(a) The draft to be created
(b) Limitation of construction facilities
(c) Control of pollution
(d) Quantity of flue gases to be handled
(e) All of the above
Answer: (e) All of the above
Q: The vacuum for reciprocating steam engines compared to steam turbines is _________.
(a) More
(b) Equal
(c) Less
(d) Could be more or less depending on the size of plant
(e) None of the above
Answer: (c) Less
Q: In locomotives, the draught is produced by _________.
(a) Chimney
(b) Induced draft fan
(c) Both combined (a) and (b)
(d) Steam jet draught
(e) None of the above
Answer: (d) Steam jet draught
Q: The maximum discharge through a chimney occurs when the height of the chimney is _________.
(a) Infinitely long
(b) Around 200 meters
(c) Equal to the height of the hot gas column producing draught
(d) Outside temperature is very low
(e) More than the tallest building nearby
Answer: (c) Equal to the height of the hot gas column producing draught
Q: The device used in thermal power plants to reduce the level of pollution is _________.
(a) Induced draft fan
(b) Smoke meter
(c) Chimney
(d) Precipitator
(e) Pulveriser
Answer: (d) Precipitator
Q: The ultimate analysis of fuel is determination of percentage of _________.
(a) Carbon, hydrogen, nitrogen, sulphur, moisture
(b) Fixed carbon, ash, volatile matter, moisture
(c) Higher calorific value
(d) Lower calorific value
(e) Best analysis
Answer: (a) Carbon, hydrogen, nitrogen, sulphur, moisture
Q: Spontaneous combustion is a phenomenon in which _________.
(a) All the fuel burns instantaneously producing high energy release
(b) Fuel burns with less air
(c) Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
(d) Explosion in furnace
(e) None of the above
Answer: (c) Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
Q: An economiser in a boiler _________.
(a) Increases steam pressure
(b) Increases steam flow
(c) Decreases fuel consumption
(d) Decreases steam pressure
(e) Increases life of boiler
Answer: (c) Decreases fuel consumption
Q: Sulphur content of fuels is very important to plant operators because it _________.
(a) Has high heating value
(b) Retards electric precipitation
(c) Promotes complete combustion
(d) Has highly corrosive effect
(e) Facilitates ash removal
Answer: (d) Has highly corrosive effect
Q: Gusset stays in a boiler are provided to _________.
(a) Prevent the bulging of flat surfaces
(b) Avoid explosion in furnace
(c) Prevent leakage of hot flue gases
(d) Support furnace freely from top
(e) Prevent atmospheric air leaking into furnace
Answer: (a) Prevent the bulging of flat surfaces
Q: The pour point of fuel oil is the _________.
(a) Lowest temperature at which oil will flow under set condition
(b) Storage temperature
(c) Temperature at which fuel is pumped through burners
(d) Temperature at which oil is transported
(e) None of the above
Answer: (a) Lowest temperature at which oil will flow under set condition
Q: The behaviour of coal in a furnace is determined by _________.
(a) The content of sulphur
(b) The content of ash and heating value
(c) The proximate analysis
(d) The exact analysis
(e) Its type
Answer: (c) The proximate analysis
Q: Sulphur in coal results in _________.
(a) Causing clinkering and slagging
(b) Corroding air heaters
(c) Spontaneous combustion during coal storage
(d) Facilitating ash precipitation
(e) All of the above
Answer: (e) All of the above
Q: Green coal, in order to be burnt, must be _________.
(a) Heated sufficiently
(b) Burnt in excess air
(c) Heated to its ignition point
(d) Burnt as powder
(e) Burnt as lumps
Answer: (c) Heated to its ignition point
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