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Home » Engineering » Mechanical Engineering » Aptitude Test - 12
1.If petrol is used in a diesel engine, then
A. low power will be produced
B. efficiency will be low
C. higher knocking will occur
D. low power will be produced
2.The sensing element in the control system of nuclear reactors measure the __________ of the neutron flux in the reactor.
A. temperature
B. volume
C. density
D. temperature
3.If the temperature of intake air in internal combustion engine increases, then its efficiency will
A. remain same
B. decrease
C. increase
D. remain same
4.In a coil ignition system of petrol engines, a condenser is connected across the contact-breaker in order to
A. prevent sparking across the gap between the points
B. cause more rapid break of the primary current, giving a higher voltage in the secondary circuit
C. both (a) and (b)
D. prevent sparking across the gap between the points
5.Which of the following statement is correct regarding normal cetaine?
A. It is a standard fuel used for knock rating of diesel engines.
B. Its chemical name is normal-hexadecane.
C. It has long carbon chain structure.
D. It is a standard fuel used for knock rating of diesel engines.
6.Enriched uranium is required as a fuel in a nuclear reactor, if light water is used as moderator and coolant, because light water has
A. high neutron absorption cross-section
B. low moderating efficiency
C. high neutron scatter cross-section
D. high neutron absorption cross-section
7.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. reduce maximum pressure and maximum temperature
C. increase maximum pressure and decrease maximum temperature
D. increase maximum pressure and maximum temperature
8.The ignition quality of petrol is expressed by
A. cetane number
B. octane number
C. calorific value
D. cetane number
9.The fuel valve in a four stroke cycle diesel engine
A. opens at 15� after top dead centre and closes at 20� before bottom dead centre
B. opens at 15� before top dead centre and closes at 20� after top dead centre
C. opens at top dead centre and closes at bottom dead centre
D. opens at 15� after top dead centre and closes at 20� before bottom dead centre
10.In petrol engines, advancing of the spark timing will __________ the knocking tendency.
A. not effect
B. decrease
C. increase
D. not effect
11.The knocking tendency in compression ignition engines for a given fuel will be
A. enhanced by decreasing compression ratio
B. enhanced by increasing compression ratio
C. dependent on other factors
D. enhanced by decreasing compression ratio
12.In a four stroke cycle engine, the sequence of operations is
A. suction, compression, expansion and exhaust
B. suction, expansion, compression and exhaust
C. expansion, compression, suction and exhaust
D. suction, compression, expansion and exhaust
13.Diesel as compared to petrol is
A. highly ignitable
B. more difficult to ignite
C. less difficult to ignite
D. highly ignitable
14.The probability of knocking in diesel engines is increased by
A. high self ignition temperature
B. low volatility
C. higher viscosity
D. high self ignition temperature
15.A diesel engine, during suction stroke, draws
A. air only
B. diesel only
C. a mixture of diesel and air
D. air only
16.Anti-knock for compression ignition engines is
A. napthene
B. tetra ethyl lead
C. amyl nitrate
D. napthene
17.In an internal combustion engine, the process of removing the burnt gases from the combustion chamber of the engine cylinder is known as
A. scavenging
B. detonation
C. supercharging
D. scavenging
18.Supercharging is the process of supplying the intake air to the engine cylinder at a density __________ the density of the surrounding atmosphere.
A. equal to
B. less than
C. greater than
D. equal to
19.The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of
A. Morse test
B. prony brake test
C. motoring test
D. Morse test
20.In a four stroke cycle petrol engine, , the compression
A. starts at 40� after bottom dead centre and ends at 30� before top dead centre
B. starts at 40� before bottom dead centre and ends at 30� after bottom dead centre
C. starts at bottom dead centre and ends at top dead centre
D. starts at 40� after bottom dead centre and ends at 30� before top dead centre
21.During idling, a petrol engine requires __________ mixture.
A. lean
B. rich
C. chemically correct
D. lean
22.In natural uranium, the constituents of three naturally occuring isotopes are
A. U234 = 0.006%, U235 = 0.712% and U238 = 99.282%
B. U234 = 0.712%, U235 = 0.006% and U238 = 99.282%
C. U234 = 99.282%, U235 = 0.006% and U238 = 0.712%
D. U234 = 0.006%, U235 = 0.712% and U238 = 99.282%
23.Stoichiometric ratio is
A. chemically correct air-fuel ratio by weight
B. chemically correct air-fuel ratio by volume
C. actual air-fuel ratio for maximum efficiency
D. chemically correct air-fuel ratio by weight
24.Which of the following fuel has little tendency towards detonation ?
A. Benzene
B. Iso-octane
C. Normal heptane
D. Benzene
25.In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a
A. fuel pump
B. fuel injector
C. spark plug
D. fuel pump
26.Enriched uranium may contain fissionable contents from
A. 1 to 40%
B. 10 to 50%
C. 1 to 80%
D. 1 to 40%
27.In a four stroke engine, the working cycle is completed in
A. one revolution of the crankshaft
B. two revolutions of the crankshaft
C. three revolutions of the crankshaft
D. one revolution of the crankshaft
28.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. when the cross-section of the nozzle increases continuously from entrance to exit
29.A turbine is said to have an axial discharge when the steam leaves the blade tip at ____ to the direction of the blade motion.
A. 60�
B. 90�
C. 180�
D. 60�
30.The flow through a nozzle is regarded as
A. constant volume flow
B. constant pressure flow
C. isothermal flow
D. constant volume flow
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