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Multiple choice question for engineering

Set 1

1. The reference fuels for knock rating of spark ignition engines would include
a) normal octane and aniline
b) iso-octane and normal hexane
c) iso-octane and alpha-methyl naphthalene
d) normal heptane and iso-octane

View Answer

Answer: d [Reason:] The reference fuels for knock rating of spark ignition engines would include normal heptane and iso-octane.

2. The purpose of testing an internal combustion engine is
a) to conform the data used in design, the validity of which may be doubtful
b) to satisfy the customer regarding the performance of the engine
c) to determine the information, which cannot be obtained by calculations
d) all of the mentioned

View Answer

Answer: d [Reason:] The purpose of testing an internal combustion engine is to conform the data used in design, the validity of which may be doubtful; to satisfy the customer regarding the performance of the engine & to determine the information, which cannot be obtained by calculations.

3. Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to
a) overheated spark plug points
b) red hot carbon deposits on cylinder walls
c) cylinder walls being too hot
d) any of the mentioned

View Answer

Answer: d [Reason:] Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to either overheated spark plug points, red hot carbon deposits on cylinder walls, & cylinder walls being too hot.

4. The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be
a) 20%
b) 25%
c) 50%
d) 55%

View Answer

Answer: c [Reason:] The Thermal efficiency of a standard Otto cycle for a compression ratio r is given by, N = 1 – (1/r1.4-1).

5. The fuels in order of decreasing knock tendency for spark ignition engines are
a) Paraffin, aromatic, napthene
b) Paraffin, napthene, aromatic
c) Napthene, aromatics, paraffin
d) Napthene, paraffin, aromatic

View Answer

Answer: b [Reason:] The fuels in order of decreasing knock tendency for spark ignition engines are Paraffin, napthene, aromatic.

6. In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.
a) equal to
b) below
c) above
d) middle

View Answer

Answer: b [Reason:] In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is below the atmospheric pressure.

7. Solid fuel fabricated into various small shapes, which are assembled to form fuel elements, is in the form of
a) pallets
b) plates
c) pins
d) all of the mentioned

View Answer

Answer: d [Reason:] Solid fuel fabricated into various small shapes are of the form of pallets, plates, pins, etc.

8. A diesel engine is __________ as compared to petrol engine, both running at rated load.
a) equally efficient
b) more efficient
c) less efficient
d) all of the mentioned

View Answer

Answer: b [Reason:] A diesel engine is more efficient as compared to petrol engine, both running at rated load.

9. A higher compression ratio causes
a) increase in detonation
b) pre-ignition
c) an acceleration in the rate of combustion
d) any one of the mentioned

View Answer

Answer: d [Reason:] A higher compression ratio causes increased detonation, increased rate of combustion & pre-ignition.

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

View Answer

Answer: a [Reason:] Inlet valve closing before bottom dead centre would reduce the volumetric efficiency of a vertical compression ignition engine.

Set 2

1. Which of these terms defines the pressure difference in the furnace?
a) draught
b) duct
c) stack
d) chimney

View Answer

Answer: a [Reason:] The term ‘draught’ is used to define the static pressure in the furnace, in the various ducts and the stack.

2. The draught or pressure difference for a chimney of height of H metres is given by
a) Δp=gH(ρa-ρg)
b) Δp=gH(ρg-ρa)
c) Δp=gHρg
d) Δp=gH(ρa+ρg)

View Answer

Answer: a [Reason:] The draught produced is given by Δp=gH(ρa-ρg).

3. Which of these is not a type of mechanical draft system for a furnace?
a) balanced draft
b) induced draft
c) forced draft
d) actuated draft

View Answer

Answer: d [Reason:] The three types of mechanical drafts are balanced, induced and forced drafts.

4. Stack heat losses can be minimised by
a) using low c.v. fuels
b) controlling the excess air
c) oxygen enrichment of combustion air
d) maintaining proper draft in the furnace

View Answer

Answer: b [Reason:] Excess amount of air leads to significant losses in energy due to heat loss through flue gases.

5. Which of these accentuates clinkering trouble on furnace grate burning coal?
a) low reactivity of carbonised residue containing high proportions of iron and sulphur
b) low forced draught and low fuel bed temperature
c) thick fire bed and preheated primary air
d) all of the mentioned

View Answer

Answer: d [Reason:] All these reasons lead to clinkering.

6. Natural draught produced by a chimney depends upon
a) density of chimney gases
b) height of chimney
c) both ‘a’ and ‘b’
d) none of the mentioned

View Answer

Answer: c [Reason:] Natural draught depends on density of gases in chimney and its height.

7. In a furnace employing forced draught compared to induced draught
a) the fan operates hot and hence blades are liable to corrosion and erosion
b) positive pressure exists in the furnace
c) air is sucked in, so air leaks are more and hence furnace efficiency is reduced
d) none of the mentioned

View Answer

Answer: c [Reason:] A positive pressure exists in the furnace employing forced draught.

8.Which of the following types of the fans has the highest cost?
a) centrifugal fans
b) axial fans
c) primary fans
d) gas recirculation fans

View Answer

Answer: b [Reason:] Axial fans have the highest cost.

9. Which of these is not a type of drive of variable speed control?
a) variable speed turbine
b) hydraulic coupling
c) multiple speed ac motor
d) electronically adjustable turbine drive

View Answer

Answer: d [Reason:] Except ‘d’, all other are a type of drive in variable speed control.

Set 3

1. The steam power plant is a bulk energy converter where fuel energy is converted to?
a) heat energy
b) electrical energy
c) chemical energy
d) none of the mentioned

View Answer

Answer: b [Reason:] Energy conversion in a steam power plant is as below Fuel energy to Electricity.

2. Rate of energy released by the combustion of the fuel is given by?
a) Fuel burning rate x Calorific Value of the fuel
b) Fuel burning rate / Calorific Value of the fuel
c) Fuel burning rate + Calorific Value of the fuel
d) Fuel burning rate – Calorific Value of the fuel

View Answer

Answer: a [Reason:] Rate of energy released by the combustion of the fuel is given by, Fuel burning rate x Calorific Value of the fuel.

3. The overall efficiency noverall of a steam power plant is given by?
a) noverall = (power available at the generator terminals / (Fuel burning rate x Calorific Value of the fuel))
b) noverall = (power available at the generator terminals + (Fuel burning rate x Calorific Value of the fuel))
c) noverall = (power available at the generator terminals – (Fuel burning rate x Calorific Value of the fuel))
d) none of the mentioned

View Answer

Answer: a [Reason:] The overall efficiency noverall of a steam power plant is given by, noverall = (power available at the generator terminals / (Fuel burning rate x Calorific Value of the fuel)).

4. Which of the following shows the correct relation? (nboiler denotes efficiency of a boiler)
a) nboiler = (rate of energy absorption by water to form steam / rate of energy released by the combustion of fuel)
b) nboiler = (rate of energy absorption by water to form steam + rate of energy released by the combustion of fuel)
c) nboiler = (rate of energy absorption by water to form steam – rate of energy released by the combustion of fuel)
d) nboiler = (rate of energy absorption by water to form steam x rate of energy released by the combustion of fuel)

View Answer

Answer: a [Reason:] The efficiency of a boiler is given by the following expression, nboiler = (rate of energy absorption by water to form steam / rate of energy released by the combustion of fuel).

5. The mechanical efficiency of a turbine is given by? (ntm denotes the mechanical efficiency)
a) ntm = (brake output of the turbine x internal output of the turbine)
b) ntm = (internal output of the turbine / break output of the turbine)
c) ntm = (brake output of the turbine / internal output of the turbine)
d) ntm = (brake output of the turbine – internal output of the turbine)

View Answer

Answer: c [Reason:] The expression for the turbine mechanical efficiency is given by, ntm = (brake output of the turbine / internal output of the turbine).

6. If Q1 represents the rate of heat addition to the cycle and W represents net cycle work output, the expression for net cycle heat rate is ?
a) Q1 + W
b) Q1 / W
c) Q1 / (1/ W)
d) Q1 x W

View Answer

Answer: b [Reason:] The expression for the net cycle heat rate is given by, Net cycle heat rate(HR) = Q1 / W.

7. The generator efficiency n of the electric alternator is?
a) n = (electrical output at generator terminals / Brake output of the turbine)
b) n = (electrical output at generator terminals x Brake output of the turbine)
c) n = (electrical output at generator terminals / (1/ Brake output of the turbine))
d) none of the mentioned

View Answer

Answer: a [Reason:] The generator efficiency of the electric alternator is defined as the ratio of electrical output at generator terminals to the brake output of the turbine.

8. Which of these is not an auxiliary equipment in a power plant?
a) Fans
b) Crushers
c) Galvanisers
d) Conveyors

View Answer

Answer: c [Reason:] The auxiliary equipment in a power plant are those equipment which are driven by the electricity taken from the generated power of the plant.

9. Which of these shows the formula for the efficiencies of the auxiliaries n1?
a) n1 = (net power transmitted by the generator x gross power produced by the plant)
b) n1 = (net power transmitted by the generator / gross power input to the plant)
c) n1 = (net power transmitted by the generator / gross power produced by the plant)
d) n1 = (net power transmitted by the generator / gross power transferred by the plant)

View Answer

Answer: c [Reason:] The auxiliary equipment or auxiliaries in a power plant are those equipment which are driven by the electricity taken from the generated power of the plant. Their efficiency is given by, n1 = (net power transmitted by the generator / gross power produced by the plant).

10. What approximate percentage of energy in the fuel is converted to electricity?
a) 55%
b) 45%
c) 35%
d) 25%

View Answer

Answer: c [Reason:] Only 34% of the energy stored in the fuel is converted to electricity & 66% is lost. The maximum loss of energy takes place in the condenser where heat is rejected to cooling water.

11. Heat rejection in a condenser is to?
a) cooled water
b) coolant
c) cooling water
d) none of the mentioned

View Answer

Answer: c [Reason:] The maximum loss of energy takes place in the condenser where heat is rejected to cooling water. This is the loss due to heat to work energy conversion in the cycle or the loss due to second law.

12. Heat rate indicates?
a) heat added per unit volume
b) heat added per unit of work produced
c) heat added per unit of mass stored
d) heat added per unit area

View Answer

Answer: b [Reason:] The parameter which readily affects the fuel economy is the heat rate which is inversely proportional to the efficiency, and hence the lower its value the better. It broadly indicates the heat added per unit of work produced.

13. Which of the following parameters affects the fuel economy?
a) heat constant
b) specific heat
c) heat rate
d) heat consumption

View Answer

Answer: c [Reason:] The parameter which readily affects the fuel economy is the heat rate which is inversely proportional to the efficiency, and hence the lower its value the better. It broadly indicates the heat added per unit of work produced.

14. Gross cycle heat rate is equal to?
a) (rate of heat addition / turbine output)
b) (rate of heat rejection / turbine input)
c) (heat rejected / turbine output)
d) none of the mentioned

View Answer

Answer: a [Reason:] The gross cycle heat rate is given by, Gross cycle heat rate = (rate of heat addition / turbine output).

15. The relation between heat rate & efficiency is?
a) both are directly proportional
b) both are inversely proportional
c) they are independent of each other
d) heat rate is also called efficiency

View Answer

Answer: b [Reason:] The parameter which readily affects the fuel economy is the heat rate which is inversely proportional to the efficiency, and hence the lower its value the better. It broadly indicates the heat added per unit of work produced.

Set 4

1. Convergent part of the nozzle is usually sharp while the divergent one is?
a) slopy
b) gradual
c) both the above mentioned
d) none of the mentioned

View Answer

Answer: b [Reason:] The divergent part of the nozzle is gradual in comparison to the convergent part.

2. What is another name of converging nozzle?
a) diverging nozzle
b) subsonic nozzle
c) supersonic nozzle
d) none of the mentioned

View Answer

Answer: b [Reason:] Another name of converging nozzle is Subsonic Nozzle.

3. Based on the type of applications, the nozzles are divided into?
a) 3 types
b) 4 types
c) 2 types
d) 5 types

View Answer

Answer: c [Reason:] There are 2 types of nozzles based on their applications, namely Reamed & Foil nozzles.

4. Which of the following is used in high pressure impulses stages of steam turbine?
a) Reamed Nozzles
b) Foil Nozzles
c) Both the above mentioned
d) None of the mentioned

View Answer

Answer: a [Reason:] Reamed nozzle is used in high pressure impulses stages of steam turbine.

5. Angle of divergence in reamed nozzles is?
a) 10 deg
b) 12 deg
c) 14 deg
d) 16 deg

View Answer

Answer: b [Reason:] The angle of divergence in reamed nozzles is approx. 12 degrees.

6. The nozzle formed by curved airfoil sections is called?
a) Curved nozzle
b) Airfoil Nozzle
c) Foil nozzle
d) Reamed nozzle

View Answer

Answer: c [Reason:] Foil nozzle is the nozzle formed by curved air foil sections.

7. There are mainly _______ types of turbines?
a) 2
b) 3
c) 4
d) 5

View Answer

Answer: a [Reason:] There are mainly two types of Turbines- Impulse & Reaction Turbine.

8. Moving blades are placed next to?
a) Fixed blades
b) Nozzle
c) Nozzle vanes
d) None of the mentioned

View Answer

Answer: c [Reason:] Moving blades are positioned next to the nozzle vanes to allow sufficient flow.

9. The incoming steam inside the turbine goes into?
a) Steam vanes
b) Steam chest
c) Nozzle vanes
d) Moving blades

View Answer

Answer: b [Reason:] The incoming steam is housed into the steam chest situated just below the steam inlet.

10. One row of nozzles followed by one row of blades is called?
a) a group of turbine
b) a step of turbine
c) a process of turbine
d) a stage of turbine

View Answer

Answer: d [Reason:] One row of nozzles followed by one row of blades is called a stage of Turbine.

Set 5

1. The maximum work attainable as the system comes in equilibrium with surrounding is called?
a) Energy
b) Availability
c) Exergy
d) Entropy

View Answer

Answer: c [Reason:] Exergy is defined as, “The maximum work attainable as the system comes in equilibrium with surrounding”.

2. More the exergy, ___________ is the work obtained from the system.
a) more
b) less

View Answer

Answer: a [Reason:] Exergy is defined as, “The maximum work attainable as the system comes in equilibrium with surrounding”. Naturally, more the exergy, more is the work obtained from the system.

3. Which of these is a measure of energy quality?
a) Entropy
b) Enthalpy
c) Exergy
d) none of the mentioned

View Answer

Answer: c [Reason:] Exergy is also a measure of the quality of energy apart from the work obtained from the system.

4. Exergic __________ is a measure of the perfectness of a thermal system.
a) enthalpy
b) efficiency
c) strength
d) degree

View Answer

Answer: b [Reason:] Exergy is also a measure of the quality of energy apart from the work obtained from the system. For this, exergic efficiency is a measure of the perfectness of a thermal system.

5. The values of dry solid fuel ratio are highest in?
a) Coke
b) Coal
c) Wood
d) Natural Gas

View Answer

Answer: c [Reason:] The values of the ratio are 1.05 for coke, 1.05-1.10 for coal, 1.15-1.30 for wood & 1.04 for Natural Gas.

6. Choice of a gas turbine depends most on which of these factors?
a) Compression ratio
b) Cut-off ratio
c) Pressure ratio
d) none of the mentioned

View Answer

Answer: c [Reason:] The working a Brayton cycle can be estimated most effectively by pressure ratio, so it becomes the most important factor.

7. Gas turbines with intercooling, regeneration & reheat are more suitable for combined cycles.
a) True
b) False

View Answer

Answer: b [Reason:] Increasing the stages in a gas turbine with combined cycles will decrease its efficiency.

8. What is the optimum pressure ratio range for a gas turbine to obtain optimum efficiency?
a) 7-8.5
b) 10.5-12
c) 9.5-10
d) 10-20

View Answer

Answer: b [Reason:] The optimum pressure ratio range for a gas turbine to obtain optimum efficiency is 10.5-12.

9. What is that temperature called to which the exhaust gases of a gas turbine are cooled to?
a) Oxygen Dewpoint
b) Carbon dioxide Dewpoint
c) Nitrogen Dewpoint
d) Sulphuric Acid Dewpoint

View Answer

Answer: d [Reason:] As the maximum temperature of cooling that can be reached has to be the dewpoint of one of these gases, so the dewpoint of Sulphuric Acid [Sulphur dioxide discharge] is chosen.

10. With an increase in the combined cycle pressure ratio, the efficiency of the bottoming cycle?
a) increases
b) decreases
c) remains same
d) none of the mentioned

View Answer

Answer: b [Reason:] The efficiency of the bottoming cycle is inversely proportional to combined cycle pressure ratio, so this relation.