I.C. Engines Questions and Answers

I.C. Engines Questions and Answers

1. The working cycle in case of four stroke engine
is completed in following number of revolutions of
crankshaft
(a) 1/2
(b) 1
(c) 2
(d) 4
(e) 8.
Ans: c
2. In a diesel engine, the fuel is ignited by
(a) spark
(b) injected fuel
(c) heat resulting from compressing air that is
supplied for combustion
(d) ignition
(e) combustion chamber.
Ans: c
3. Scavenging air in diesel engine means
(a) air used for combustion sent under pres-sure
(b) forced air for cooling cylinder
(c) burnt air containing products of combustion
(d) air used for forcing burnt gases out of engine's
cylinder during the exhaust period
(e) air fuel mixture.
Ans: d
4. 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) providing forced cooling air
(c) injecting excess fuel for raising more load
(d) supplying compressed air to remove combustion
products fully
(e) raising exhaust pressure.
Ans: a
5. Does the supply of scavenging air at a density
greater than that of atmosphere mean engine is
supercharged ?
(a) yes
(b) no
(c) to some extent
(d) unpredictable
(e) depends on other factors.
Ans: b
6. The ratio of indicated thermal efficiency to the
corresponding air standard cycle efficiency is called
(a) net efficiency
(b) efficiency ratio
(c) relative efficiency
(d) overall efficiency
(e) cycle efficiency.
Ans: c
7. Compression ratio of LC. engines is
(a) the ratio of volumes of air in cylinder before
compression stroke and after compression stroke
(b) volume displaced by piston per stroke and
clearance volume in cylinder
(c) ratio of pressure after compression and before
compression
(d) swept volume/cylinder volume
(e) cylinder volume/swept volume.
Ans: a
8. The air standard efficiency of an Otto cycle
compared to diesel cycle for the given compression
ratio is
(a) same
(b) less
(c) more
(d) more or less depending on power rating
(e) unpredictable.
Ans: c
9. The calorific value of gaseous fuels is expressed
in terms of
(a) kcal
(b) kcal/kg
(c) kcal/m2
(d) kcal/n?
(e) all of the above.
Ans: d
11. If the intake air temperature of I.C. engine
increases, its efficiency will
(a) increase
(b) decrease
(c) remain same
(d) unpredictable
(e) depend on other factors.
Ans: b
12. All heat engines utilize
(a) low heat value of oil
(b) high heat value of oil
(c) net claorific value of oil
(d) calorific value of fuel
(e) all of the above.
Ans: a
13. An engine indicator is used to determine the
following
(a) speed
(b) temperature
(c) volume of cylinder
(d) m.e.p. and I.H.P.
(e) BHP.
Ans: d
14. Fuel oil consumption guarantees for I .C. engine
are usually based on
(a) low heat value of oil
(b) high heat value of oil
(c) net calorific value of oil
(d) calorific value of fuel
(e) all of the above.
Ans: b
17. If the compression ratio of an engine working on
Otto cycle is increased from 5 to 7, the %age
increase in efficiency will be
(a) 2%
(b) 4%
(c) 8%
(d) 14%
(e) 27%.
Ans: d
18. In case of gas turbines, the gaseous fuel
consumption guarantees are based on
(a) high heat value
(b) low heat value
(c) net calorific value
(d) middle heat value
(e) calorific value.
Ans: b
19. In a typical medium speed 4-stroke cycle diesel
engine the inlet valve
(a) opens at 20° before top dead center and closes
at 35° after the bottom dead center
(b) opens at top dead center and closes at bottom
dead center
(c) opens at 10° after top dead center and closes
20° before the bottom dead center
(d) may open or close anywhere
(e) remains open for 200°.
Ans: a
20. The pressure and temperature at the end of
compression stroke in a petrol engine are of the
order of
(a) 4 - 6 kg/cm2 and 200 - 250°C
(b) 6 - 12 kg/cm2 and 250 - 350°C
(c) 12 - 20 kg/cm2 and 350 - 450°C
(d) 20 - 30 kg/cm2 and 450 - 500°C
(e) 30 - 40 kg/cm2 and 500 - 700°C.
Ans: b
21. The pressure at the end of compression in the
case of diesel engine is of the order of
(a) 6 kg/cm
(b) 12kg/cmz
(c) 20 kg/cmz
(d) 27.5 kg/cmz
(e) 35 kg/cm
Ans: e
22. The maximum temperature in the I.C. engine
cylinder is of the order of
(a) 500- 1000°C
(b) 1000- 1500°C
(c) 1500-2000°C
(d) 2000-2500°C
(e) 2500-3000°C
Ans: d
23. The thermal efficiecny of a diesel cycle having
fixed compression ratio, with increase in cut-off
ratio will
(a) increase
(b) decrease
(c) be independent
(d) may increase or decrease depending on other
factors
(e) none of the above.
Ans: b
24. Pick up the wrong statement
(a) 2-stroke engine can run in any direction
(b) In 4-stroke engine, a power stroke is obtained in
4-strokes
(c) thermal efficiency of 4-stroke engine is more
due to positive scavenging
(d) petrol engines work on otto cycle
(e) petrol engines occupy more space than diesel
engines for same power output.
Ans: e
25. Combustion in compression ignition engines is
(a) homogeneous
(b) heterogeneous
(c) both (a) and (b)
(d) laminar
(e) turbulent.
Ans: b
26. The fuel in diesel engine is normally injected at
pressure of
(a) 5-10 kg/cm2
(b) 20-25 kg/cm2
(c) 60-80 kg/cm2
(d) 90-130 kg/cm2
(e) 150-250 kg/cm2
Ans: d
27. The specific fuel consumption per BHP hour for
diesel engine is approximately
(a) 0.15 kg
(b) 0.2 kg
(c) 0.25 kg
(d) 0.3 kg
(e) 0.35 kg.
Ans: b
28. The temperature of interior surface of cylinder
wall in normal operation is not allowed to exceed
(a) 80°C
(b) 120°C
(c) 180°C
(d) 240°C
(e) 320°C.
Ans: c
30. Crankcase explosion in I.C. engines usuall
occurs as
(a) first a mild explosion followed by a bi explosion
(b) first a big explosion followed by a mil explosion
(c) both mild and big explosions occi simultaneously
(d) never occurs
(e) unpredictable.
Ans: a
31. Compression loss in I.C engines occurs duto
(a) leaking piston rings
(b) use of thick head gasket
(c) clogged air-inlet slots
(d) increase in clearance volume caused b bearing-
bushing wear
(e) all of the above.
Ans: e
32. The specific fuel consumption per BH hour for a
petrol engine is approximately
(a) 0.15 kg
(b) 0.2 kg
(c) 0.25 kg
(d) 0.3kg
(e) 0.35 kg.
Ans: c
33. The air requirement of a petrol engine during
starting compared to theoretical airequired for
complete combustion is
(a) more
(b) loss
(c) same
(d) may be more or less depending on engine
capacity
(e) unpredictable.
Ans: b
34. The inlet value of a four stroke cycle I.C engine
remains open for nearly
(a) 180°
(b) 125°
(c) 235°
(d) 200°
(e) 275°.
Ans: c
35. Which of the following is not an interns
combustion engine
(a) 2-stroke petrol engine
(b) 4-stroke petrol engine
(c) diesel engine
(d) gas turbine
(e) steam turbine.
Ans: e
36. Pick up the false statement
(a) Thermal efficiency of diesel engine i about 34%
(b) Theoretically correct mixture of air am petrol is
approximately 15 : 1
(c) High speed compression engines operate on
dual combustion cycle
(d) Diesel engines are compression ignition engines
(e) S.I. engines are quality-governed engines.
Ans: e
37. If one cylinder of a diesel engine receives more
fuel than the others, then for that cylinder the
(a) exhaust will be smoky
(b) piston rings would stick into piston grooves
(c) exhaust temperature will be high
(d) engine starts overheating
(e) scavenging occurs.
Ans: e
38. The output of a diesel engine can be increased
without increasing the engine revolution or size in
following way
(a) feeding more fuel
(b) increasing flywheel size
(c) heating incoming air
(d) scavenging
(e) supercharging.
Ans: e
39. It the temperature of intake air in IC engines is
lowered, then its efficiency will
(a) increase
(b) decrease
(c) remain same
(d) increase upto certain limit and then decrease
(e) decrease upto certain limit and then in-crease.
Ans: a
40. In a typical medium speed 4-stroke cycle diesel
engine
(a) compression starts at 35° after bottom dead
center and ends at top dead center
(b) compression starts at bottom dead center and
ends at top dead center
(c) compression starts at 10° before bottom dead
center and, ends just before top dead center
(d) may start and end anywhere
(e) none of the above.
Ans: a
41. For the same compression ratio
(a) Otto cycle is more efficient than the Diesel
(b) Diesel cycle is more efficient'than Otto
(c) both Otto and Diesel cycles are, equally efficient
(d) compression ratio has nothing to do with
efficiency
(e) which is more efficient would depend on engine
capacity.
Ans: a
42.  The precess of breaking up or a lipuid into fine
droplets by spraying is called
(a) vaporisation
(b) carburetion
(c) ionisation
(d) injection
(e) atomisation.
Ans: e
43. As a result of detonation in an I.C. engine,
following parameter attains very high value
(a) peak pressure
(b) rate of rise of pressure
(c) rate of rise of temperature
(d) peak temperature
(e) rate of rise of horse-power.
Ans: b
44. Which of the following statements is correct?
(a) All the irreversible engines have same
efficiency
(b) All the reversible engines have same
efficiency
(c) Both Rankine and Caront cycles have same
efficiency between same temperature limits
(d) All reversible engines working between same
temperature limits have same-efficiency
(e) Between same temperature limits, both petrol
and diesel engines have same efficiency.
Ans: d
45. Most high speed compression engines operate
on
(a) Diesel cycle
(b) Otto cycle
(c) Dual combustion cycle
(d) Special type of air cycle
(e) Carnot cycle.
Ans: c
48. The accunmulation of carbon in a cylinder
results in increase of
(a) clearance volume
(b) volumetric efficiency
(c) ignition time
(d) effective compression ratio
(e) valve travel time.
Ans: d
49. Which of the following medium is compressed in
a Diesel engine cylinder
(a) air aione
(b) air and fuel
(c) air and lub oil
(d) fuel alone
(e) air, fuel and lub oil.
Ans: a
54. The air-fuel ratio of the petrol engine is
controlled by
(a) fuel pump
(b) governor
(c) injector
(d) carburettor
(e) scavenging.
Ans: d
55. In a typical medium speed, 4-stroke cycle diesel
engine
(a) fuelinjection starts at 10° before to dead center
and ends at 20° after tor dead center
(b) fuel injection starts at top dead center and ends
at 20° after top dead center
(c) fuel injection starts at just before top dead
center and ends just after top deac center
(d) may start and end anywhere
(e) none of the above.
Ans: a
56. Diesel fuel, compared to petrol is
(a) less difficult to ignite
(b) just about the same difficult to ignite
(c) more difficult to ignite
(d) highly ignitable
(e) none of the above.
Ans: c
57. In diesel engine the diesel fuel injected into
cylinder would burn instantly at about compressed
air temperature of
(a) 250°C
(b) 500°C
(c) 1000°C
(d) 150CPC
(e) 2000°C.
Ans: c
58. When crude oil is heated, then which of the
following hydrocarbon is given off first.
(a) kerosene
(b) gasoline
(c) paraffin
(d) diesel
(e) natural gas.
Ans: e
59. The rating of a diesel engine, with increase in
airintlet temperature, will
(a) increase linearly
(b) decrease linearly
(c) increase parabolically
(d) decrease parabolically
(e) first decrease linearly and then increase
parabolically.
Ans: b
60. A 75 cc engine has following parameter as 75 cc
(a) fuel tank capacity
(b) lub oil capacity
(c) swept volume
(d) cylinder volume
(e) clearance volume.
Ans: c
61. A heat engine utilises the
(a) calorific value of oil
(b) low heat value of
(c) high heat value of oil
(d) mean heat value of oil
(e) all of the above.
Ans: c
62. Gaseous-fuel guarantees are based on
(a) calorific value of oil
(b) low heat value of oil
(c) high heat value of oil
(d) mean heat value of oil
(e) all of the above.
Ans: b
63. Fuel consumption of diesef engines is not
guaranteed at one quarter load because at such low
loads
(a) the friction is high
(b) the friction is unpredictable
(c) the small difference in cooling water
temperature or in internal friction has a
disproportionate effect
(d) the engine is rarely operated
(e) none of the above.
Ans: c
64. Polymerisation is a chemical process in
which molecules of a compound become
(a) larger
(b) slowed down
(c) smaller
(d) liquid
(e) gaseous.
Ans: a
65. The term scavenging is generally associated
with
(a) 2-stroke cycle engines
(b) 4-stroke cycle engines
(c) aeroplane engines
(d) diesel engines
(e) high efficiency engines.
Ans: e
66. In diesel engine, the compression ratio in
comparison to expansion ratio is
(a) same
(b) less
(G) more
(d) variable
(e) more/less depending on engine capacity.
Ans: c
67. The cam shaft of a four stroke I.C. engine
running at 1500 rmp will run at
(a) 1500 rpm
(b) 750 rpm
(c) 3000 rpm
(d) any value independent of engine speed
(e) none of the above.
Ans: b
68. Engine pistons 'are usually made of aluminium
alloy because it
(a) is lighter
(b) wears less
(c) absorbs shocks
(d) is stronger
(e) does not react with fuel and lub oil.
Ans: a
69. Most high speed compression engines operate
on
(a) Otto cycle
(b) Diesel cycle
(c) Dual cycle
(d) Carnot cycle
(e) Two stroke cycle.
Ans: c
70. The specific fuel consumption of a petrol engine
compared to diesel engine of same H.P. is
(a) same
(b) more
(c) less
(d) less or more depending on operating conditions
(e) unpredictable.
Ans: b
71. A diesel engine as compared to petrol engine
(both running ar rated load) is
(a) more efficient
(b) less efficient
(c) equally efficient
(d) unperdictable
(e) other factors will decide it.
Ans: a
72.  The size of inlet valve of.an engine in
comparison to exhaust valve is
(a) more
(b) less
(c) same
(d) more/less depending on capacity of engine
(e) varies from design to design.
Ans: b
74. In a cycle, the spark lasts roughly for
(a) 1 sec
(b) 0.1 sec
(c) 0.01 sec
(d) 0.001 sec
(e) 0.0001 sec.
Ans: d
75. Which of the following is false statement :
Excess quantities of sulphur in diesel fuel are
Objectionable because it may cause the following
(a) piston ring and cylinder wear
(b) formation of hard coating on piston skirts
(c) oil sludge in the engine crank case
(d) detonation
(e) forms corrosive acids.
Ans: d
76. Which of the following is false statement. Some
of the methods used to reduce diesel smoke are as
follows
(a) using additives in the fuel
(b) engine derating i.e. reducing the maxi-mum flow
of fuel
(c) increasing the compression ratio
(d) adherence to proper fuel specification
(e) avoidance of overloading.
Ans: c
77. The fuel air ratio in a petrol engine fitted with
suction carburettor, operating with dirty air filter as
compared to clean filter will be
(a) higher
(b) lower
(c) remain unaffected
(d) unpredictable
(e) none of the above.
Ans: a
78. Pick up the wrong statement about
supercharging
(a) supercharging reduces knocking in diesel
engines
(b) there can be limited supercharging in petrol
engines because of detonation
(c) supercharging at high altitudes is essential
(d) supercharging results in fuel economy
(e) supercharging is essential in aircraft engines.
Ans: d
79. The actual volume of fresh charge admitted in
4-stroke petrol engine is
(a) equal to stroke volume
(b) equal to stroke volume and clearance volume
(c) less than stroke volume
(d) more than stroke volume
(e) more than cylinder volume.
Ans: c
80. The magneto in an automobile is basically
(c) transformer
(b) d.c. generator
(c) capacitor
(d) magnetic circuit
(e) a.c. generator.
Ans: b
81. The reason for supercharging in any engine is to
(a) increase efficiency
(b) increase power
(c) reduce weight and bulk for a given out-put
(d) effect fuel economy
(e) none of the above.
Ans: c
82. The operation of forcing additional air under
pressure in the engine cylinder is known as
(a) scavenging
(b) turbulence
(c) supercharging
(d) pre-ignition
(e) dissociation and carburretion of fuel.
Ans: c
83. Supercharging is essential in
(a) diesel engines
(b) gas turbines
(c) petrol engines
(d) aircraft engines
(e) marine engines.
Ans: d
84. The minimum cranking speed in case of petrol
engine is about
(a) half the operating speed
(b) one-fourth of operating speed
(c) 250-300 rpm
(d) 60-80 rpm
(e) 10-20 rpm
Ans: d
85. In a typical medium speed 4 stroke cycle diesel
engine
(a) exhaust valve opens at 35° before bot-tom dead
center and closes at 20° after top dead center
(b) exhaust valve opens at bottom 'dead center and
closes at top dead center
(c) exhaust valve opens just after bottom dead
center and closes just before top dead center
(d) may open and close anywhere
(e) none of the above is true.
Ans: a
86. Flash point of fuel oil is
(a) minimum temperature to which1 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) temperature at which it catches fire without
external aid
(d) indicated by 90% distillation temperature, i.e.
when 90% of sample oil has distilled off
(e) none of the above.
Ans: a
87. The mean effective pressure obtained from
engine indicator indicates the
(a) maximum pressure developed
(b) minimum pressure
(c) instantaneous pressure at any instant
(d) exhaust pressure
(e) average pressure.
Ans: e
88. For the same power developed in I.C. engines,
the cheaper system is
(a) naturally aspirated
(b) supercharged
(c) centrifugal pump
(d) turbo charger
(e) none of the above.
Ans: b
89. Installation of supercharger on a four-cycle
diesel engine can result in the following percentage
increase in power
(a) upto 25%
(b) upto 35%
(c) upto 50%
(d) upto 75%
(e) upto 100%.
Ans: e
90. Scavenging is usually done to increase
(a) thermal efficiency
(b) speed
(c) power output
(d) fuel consumption
(e) all of the above.
Ans: c
91. Which of the following is the lightest and most
volatile liquid fuel
(a) diesel
(b) kerosene
(c) fuel oil
(d) gasoline
(e) lub oil.
Ans: d
92. The theoretically correct air fuel ratio for petrol
engine is of the order of
(a) 6 : 1
(b) 9 : 1
(c) 12 : 1
(d) 15 : 1
(e) 20 : 1.
Ans: d
93. Air fuel ratio for idling speed of a petrol engine is
approximately
(a) 1 : 1
(b) 5 : 1
(c) 10:1
(d) 15 : 1
(e) 20 : 1.
Ans: c
94. Air fuel ratio at which a petrol engine can not
work is
(a) 8 : 1
(b) 10 : 1
(c) 15 : 1
(d) 20 : 1 and less
(e) will work at all ratios.
Ans: d
95. For maximum power generation, the air fuel
ratio for a petrol engine for vehicles, is of the order
of
(a) 9 : 1
(b) 12 : 1
(c) 15 : 1
(d) 18 : 1
(e) 20: 1.
Ans: b
96. The following volume of air is required for
consuming 1 liter of fuel by a four stroke engine
(a) 1 m3
(b) 5 m3
(c) 5-6 m3
(d) 9-10 m3
(e) 15-18 m3.
Ans: d
97. 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
(e) temperature at which it flows easily.
Ans: b
98. A 5 BHP engine running at full load would
consume diesel of the order of
(a) 0.3 kg/hr
(b) 1 kg/hr
(c) 3 kg/hr
(d) 5 kg/hr
(e) 10 kg/hr.
Ans: b
99. Diesel engine can work on very lean air fuel
ratio of the order of 30 : 1. A petrol engine can also
work on such a lean ratio provided
(a) it is properly designed
(b) best quality fuel is used
(c) can not work as it is impossible
(d) flywheel size is proper
(e) engine cooling is stopped.
Ans: c
100. A diesel engine has
(a) 1 valve
(b) 2 valves
(b) 3 valves
(d) 4 valves
(e) no valve.
Ans: c
101. A hmh flame speed is obtained in diesel engine
when air fuel ratio is
(a) uniform throughout the mixture
(b) chemically correct mixture
(c) about 3-5% rich mixture
(d) about 10% rich mixture
(e) about 10% lean mixture.
Ans: d
102. The knock in diesel engine occurs due to
(a) instantaneous and rapid burning of the first part
of the charge
(b) instantaneous atuo iginition of last part of charge
(c) delayed burning of the first part of the charge
(d) reduction of delay period
(e) all ot the above.
Ans: a
103. The air-fuel ratio in petrol engines-is
controlled by
(a) controlling valve opening/closing
(b) governing
(c) injection
(d) carburettion
(e) scavenging and supercharging.
Ans: d
104. Volatility of diesel fuel oil is
(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
(e) temperature at which it flows easily.
Ans: d
105. Which is more viscous lub oil
(a) SEA 30
(b) SAE 4£
(c) SAE 50
(d) SAE 70
(e) SAE 80.
Ans: e
106. In the opposed piston diesel engine, the
combustion chamber is located
(a) above the piston (/;) below the piston
(c) between the pistons
(d) any when
(e) there is no such criterion.
Ans: c
107. A stoichiometric air-fuel ratio is
(a) chemically correct mixture
(b) lean mixture
(c) rich mixture for idling
(d) rich mixture for over loads
(e) the ratio used at full rated parameters.
Ans: a
108. In a naturally aspirated diesel engine, the air is
supplied by
(a) a supercharger
(b) a centrifugal blower
(c) a vacuum chamber
(d) an injection tube
(e) forced chamber
Ans: c
109. In loop scavenging, the top of the piston is
(a) flat
(b) contoured
(c) slanted
(d) depressed
(e) convex shaped.
Ans: b
110. In the crankcase method of scavenging, the air
pressure is produced by
(a) supercharger
(b) centrifugal pump
(c) natural aspirator
(d) movement of engine piston
(e) reciprocating pump.
Ans: d
111. In order to prevent formation of carbon on the
injector, the temperature of nozzle tip should be
(a) less than 100°C
(b) between 100-250°C
(c) between 250 - 300°C
(d) between 400 - 500°C
(e) between 500 - 1000°C.
11 The thermal efficiency of a petrol engine of two
stroke with crank case scavenging as compared to
four stroke petrol engine with same comperssion
ratio will be
(a) higher
(b) lower
(c) same
(d) depends on size of engine
(e) unpredictable.
113. Ignition quailty of petrol is expressed by
(a) octane number
(b) cetane number
(c) calorific value
(d) self ignition temperature
(e) distillation temperature.
114. Petrol is distilled at a temperature in range of
(a) 30 - 65°C
(b) 65 - 220°C
(c) 220-350°C
(d) 350-450°C
(e) 450-550°C.
115. Kerosene is distilled at
(a) 30 - 65°C
(b) 65 - 220°C
(c) 220 - 350°C
(d) 350 - 450°C
(e) 450-550°C.
116. Self-ignition temperature of petrol is of the
order of
(a) 150°C
(b) 240°C
(c) 370°C
(d) 450°C
(e) more than 500°C.
117. Iso-oct ,ne
(a) has octane number of 0
(b) has octane number of 50
(c) has octane number of 100
(d) is an index of detonation quality
(e) is an index of knocking quality.
118. Octane number is determined by comparing
the performance of the petrol with the following
hydrocarbons
(a) iso-octane
(b) mixture of normal heptane and iso-oc-tane
(c) alpha methyl napthalene
(d) mixture of methane and ethane
(e) mixture of paraffins and aromatics.
119. Cetane
(a) has zero cetane number
(b) has 100 cetane number
(c) helps detonation
(d) is a straight chain paraffin
(e) determines the efficiency of an I.C. engine.
120. Ethyl fluid is used
(a) to increase the octane rating of the fuel
(b) to increase the cetane rating of the fuel
(c) as a defrosting agent
(d) as a superior type of fluid compared to others
(e) to improve lubricating quality of fuel.
121. The self-ignition temperature of diesel oil
compared to petrol is
(a) higher
(b) lower
(c) same
(d) depends on quality of fuel
(e) unpredictable?
112. Normal heptane
(a) accelerates auto-ignition
(b) helps to resist auto-ignition
(c) does not affect auto-ignition
(d) has no relation with auto-ighition
(e) retards auto-ignition.
123. Cetane number is determined by comparing
the performance of diesel oil with the following
hydrocarbons
(a) cetane
(b) mixture of cetane and alphamethyl napthalene
(c) ethylene dibromide
(d) mixture of aldehydes and ketones
(e) mixture of cetane with tetra-ethyl lead
124. Which is correct statement about reaction time
for autoignition of fuel and the fuel air ratio
(a) lean mixture has high reaction time
(b) rich mixture has high reaction time
(c) chemically correct mixture has mini-mum
reaction time
(d) all of the above.
(e) non of the above.
125. Violent sound pulsations within the cylinder of
an I.C. engine are caused due to
(a) heavy turbulence
(b) improved scavenging
(c) heavy supercharging
(d) detonation
(e) preignition.
126. Auto-ignition temperature is
(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) that at which it catches fire without external aid
(d) indicated by 90% distillation temperature, i.e.,
when 90% of sample oil has distilled off
(e) indicated by 50% distillation temperature.
127. Ignition lag is
(a) the time taken by fuel after injection (before top
dead center) to reach upto auto-ignition
temperature
(b) time before actual fuel injection and the pump
plunger starts to pump fuel
(c) time corresponding to actual injection and top
dead center
(d) time corresopnding to actual ingition and top
dead center
(e) none of the above.
128. The spark plug gap is normally maintained at
(a) 0.1 to 0.2 mm
(b) 0.2 to 0.4 mm
(c) 0.45 to 0.6 mm
(d) 0.6 to 0.8 mm
(e) 0.8 to 1 mm.
129. The function of a fuel pump in a petrol pump is
to
(a) inject fuel in cylinder
(b) supply fuel when carburettor fails
(c) pump fuel so that it reaches carburettor (to
improve thermal efficiency)
(d) does not exist.
130. The delay period in petrol engine is of the order
of
(a) 0.001 sec
(b) 0.002 see
(c) 0.01 sec
(d) 0.05 sec
(e) 0.1 sec.
131. Detonation is caused by the following unstable
compounds
(a) peroxides, aldehydes and ketones
(b) peroxides, aldehydes, oxides and sul-phides
(c) aldehydes, oxides and ketones
(d) ketones and sulphur compounds
(e) none of the above.
13 If overhead clearance is less, then the following
type of engine should be selected
(a) V-type
(b) In-line
(c) Vertical
(d) Horizontal
(e) Radial.
133. Which is false statement about advantages of
V-type engine
(a) compact design requiring lesser space
(b) improved distribution of air to cylinder
(c) casting less liable to distortion
(d) reduced torsional vibration because of shorter
crankshaft
(e) less overhead clearance.
134. The pistons are usually given a coating such
as tin plating in order to
(a) reduce weight
(b) conduct heat efficiently
(c) reduce possibility of scoring
(d) reduce friction
(e) increase lubrication effect.
135. Piston rings are usually made of
(a) cast iron
(b) aluminium
(c) phosphor bronze
(d) babbitt
(e) carbon steel.
136. Piston rings are plated with
chromium,cadmium or phosphate in order to
(a) reduce cost
(b) improve surface finish
(c) prevent clogging
(d) reduce wear and eliminate scuffing
(e) improve heat transfer.
137. The top piston ring nearer to the piston crown
is known as
(a) compression ring
(b) oil ring
(c) scrapper ring
(d) groove ring
(e) leading ring.
138. In order to prevent knock in the S.I. engines,
the charge away from the spark plug should have
(a) low temperature
(b) low density
(c) long ignition delay
(d) rich mixture
(e) all of the above.
139. Diesel engines have low specific fuel
consumption compared to petrol engine. This
statement is
(a) not true
(b) true at full load
(c) true at part load
(d) true at both part and full load
(e) there could not be any such criterion.
140. To reduce the possibility of knock in the C.I.
engines, the first elements of fuel and air should
have
(a) high temperature
(b) high density
(c) short delay
(d) reactive mixture
(e) all of the above.
141. The detonation tendency in petrol engines for
specified conditions of fuel rating, compression
ratio, speed etc. can be con-trolled by having
(a) smaller cylinder bore
(b) bigger cylinder bore
(c) medium cylinder bare
(d) cylinder bore could be anything as it does not
control detonation
(e) proper stroke legth.
142. According to Recardo's theory, detonation
occurs due to
(a) instantaneous auto-ignition of last part of charge
to be burnt
(b) improper mixing of air and fuel
(c) improper combustion
(d) self ignition temperature has nothing to do
with detonation
(e) none of the above.
143. A fuel will detonate less if it has
(a) higher self ignition temperature
(b) lower self ignition temperature
(c) proper self ignition temperature
(d) self ingition temperature has nothing to do with
detonation
(e) none of the above.
144. The knocking in diesel engines for given fuel,
will be
(a) enhanced by increasing compression ratio
(b) enhanced by decreasing compression ratio
(c) unaflected by compression ratio
(d) first enhanced by increasig compression ratio
upto a limit beyond which it will be suppressed
(e) dependent on other factors.
145. The ignition of charge by some hot surface in
the engine cylinder before operation of spark plug is
known as
(a) auto ignition
(b) preignition /
(c) retarded ignition
(d) accelerated ignition
(e) detonation.
146. Injection lag is
(a) the time taken by fuel after injection (before top
dead center) to reach upto auto-ignition
temperature
(b) time before actual fuel injection and the pump
pluger starts to pump fuel
(c) time corresponding to actual injection and top
dead center
(d) time corresponding to actual ignition and top
dead center
(e) none of the above.
147. Ignition quality of diesel-fuel oil is expressed
by an index called
(a) octane number
(b) cetane number
(c) calorific value
(d) carbon content
(e) ignition temperature.
148. For best results of efficient combustion, high
speed diesel engines need an approximate cetane
number of
(a) 100
(b) 10
(c) 50
(d) 5
(e) 1.
149. Calorific value of diesel oil is of the order of
(a) 3000 kcal/kg
(b) 5000 kcal/kg
(c) 7500 kcal/kg
(d) 10000 kcal/kg
(e) 15000 kcal/kg.
150. Carbon residue in diesel oil should not be more
than
(a) 1%
(b) 0.5%
(c) 0.1%
(d) 0.01%
(e) 0.001%.
151. The most popular firing order in case of four
cylinder in-line I.C. engine is
(a) 1-2-3-4
(b) 1-3-2-4
(c) 1-4-2-3
(d) 1-2-4-3
(e) 1-3-4-
15 The compression ratio of motor cars is
(a) 5
(b) 1
(c) 10
(d) 13
(e) 16.
153. The specific gravity of diesel oil Is
(a) 1
(b) 0.7
(c) 0.85
(d) 0.5
(e) 1.25.
154. Freezing temperature of petrol is usually
(a) 0°C
(b) - 10°C
(c) 10°C
(d) less than - 30°C
(e) less than - 273°C.
155. The specific gravity of petrol is about
(a) 0.65
(b) 0.75
(c) 0.85
(d) 0.95
(e) 1.1.
156. Pick up the correct statement. Detonation can
be controlled by
(a) varying compression ratio
(b) using lian mixture
(c) retarding the spark timing
(d) reducing the r.p.m.
(e) increasing inlet pressure.
157. The efficiency of I.C. engines normally is of the
order of
(a) 15-20%
(b) 20-25%
(c) 25-30%
(d) 30-35%
(e) 35-50%.
158. The firing order in a six stroke I.C. engine is
(a) 1-3-6-5-2-4
(b) 1-4-2-5-6-3
(c) 1-6-2-5-4-3
(d) 1-5-2-6-3-4
(e) 1-5-3-4-2-6.
159. Sulphur content in diesel oil should not be more
than
(a) 10%
(b) 5%
(c) 1%
(d) 0.1%
(e) 0.01%.
160. The m.e.p. of a diesel cycle having fixed
compression ratio with increase in cut-off will
(a) increase
(b) decreae
(c) be unaffected
(d) depend on other factors
(e) unpredictable.
161. The ash content in diesel oil should bot be
more than
(a) 1%
(b) 5%
(c) 0.1%
(d) 0.01%
(e) 0.001%.
16 The pour point of diesel oil must be
(a) lower than the coldest atmospheric temperature
at which oil is to be pumped
(b) higher than above
(c) has no such relation
(d) more than 100°C
(e) none of the above.
163. High carbon content in diesel oil used for diesel
engine leads to
(a) production of highly corrosive gases corroding
the cylinder walls and exhaust system
(b) excessive engine wear
(c) damaging of both the storage tank and the
engine
(d) deposition on engine parts
(e) none of the above.
164. Exhaust pipes of engines are covered with
insulating marterial in order to
(a) keep the exhaust pipes warm
(b) reduce formation of condenstae
(c) reduce heat transfer to the engine room
(d) increase engine efficiency
(e) conserve heat.
165. Ignition timing of a multicylider petrol engine
can be adjusted by
(a) rotating the crank
(b) adjusting the spark plug gap
(c) adjusting ignition coil position
(d) rotating the distributor
(e) delaying the spark by increasing capacitor in
ignition circuit.
166. Fuel consumption with increase in back
pressure will
(a) increase
(b) decrease
(c) remain unaffected
(d) depend on other factors
(e) none of the above.
167. The cooling water requirement for diesel
engine is of the order of
(a) 0.2 to 1.0 liter per minute per h.p.
(b) 1 to 3 liters per minute per h.p.
(c) 5 to 10 liters per minute per h.p
(d) 10 to 20 liters per minute per h.p.
(e) 20-30 liters per minute per h.p.
168. A 4-stroke diesel engine needs about following
amount of air
(a) 75 cc per min. per h.p.
(b) 750 cc per min. per h.p.
(c) 7500 cc per min. per h.p.
(d) 75000 cc per min. per h.p.
(e) 750000 cc per min. per h.p.
169. Leakage past the piston rings and valve seats
in I.C. engines with increase in speed
(a) increases .
(b) decreases
(c) remains same
(d) unpredictable
(e) none of the above.
170. The heat wasted in diesel engine is of the
order of
(a) 80%
(b) 65%
(c) 50%
(d) 35%
(e ) 25%.
171. With increa.se in speed of vehicle, the back
pressure will
(a) decrease
(b) increase
(c) remain unalfected
(d) depend on other factors
(e) none of the above.
17 The function of a distributor in an automobile is
to
(a) distribute charge, equally to all  the cylinders
(b) regulate power
(c) feed lub oil to all moving parts
(d) time the spark
(e) inject fuel at appropriate time.
173. The ratio of useful power; engine friction
exhaust gas losses; cooling water, air and oil losses
for a diesel engine is of the order of
(a) 5:25:30:50
(b) 25:35:5:35
(c) 25:5:10:60
(d) 40:30:15:15
(e) 25:5:35:35.
174. For same power and same speed, the flywheel
of a four stroke engine as compared to two-stroke
I.C. engine will be
(a) smaller
(b) bigger
(c) same size
(d) dependent on other engine parameters
(e) unpredictable.
175. Air injection in I.C. engines refers to injection of
(a) air only
(b) liquid fuel only
(c) liquid fuel and air
(d) supercharging
(e) does not exist.
176. Solid injection in I.C. engines refers to injection
of
(a) liquid fuel only
(b) liquid fuel and air
(c) solid fuel
(d) solid fuel and air
(e) does not exist.
177. The system of lubrication used for motor
cycles and scooters is by
(a) forced lubrication system
(b) splash lubrication
(c) applying grease under pressure
(d) wet sump method
(e) mixing about 5% lub oil with petrol.
178. The m.e.p. of a petrol engine first increases as
the fuel air ratio is increased and then decreases on
further increase in fuel air ratio. The m.e.p. is
maximum in the zone of
(a) lean mixture
(b) chemically correct mixture
(c) rich mixture
(d) unpredictable
(e) none of the above.
179. The specific fuel consumption for a petrol
engine first decreases with increase in fuel air ratio
and then increases with further increase in fuel air
ratio. The minimum value occurs in the range of
(a) lean mixture
(b) chemically correct mixture
(c) rich mixture
(d) unpredictable
(e) none of the above.
180. The thermal efficiency of a two cycle engine as
compared to four cycle engine is
(a) more
(b) less
(c) same
(d) more upto some load and then less
(e) it may be less or more depending on several
other factors.
181. Diesel engines as compared to petrol engines
require
(a) bigger flywheel
(b) smaller flywheel
(c) same size flywheel
(d) no flywheel
(e) flywheel whose size may be less or more
depending on several other fac-tors.
183. The tendency of a diesel engine to knock
increases, if
(a) engine speed is increased
(b) engine H.P. is increased
(c) octane number of fuel is increased
(d) conperssion ratio is increased
(e) engine has to move uphill.
184. The tendency of a petrol engine to knock
increases by
(a) supercharging
(b) scavenging
(c) increasing engine H.P,
(d) reducing the spark advance
(e) increasing cetane number of fuel.
185. Free acids in diesel oil for diesel engine lead to
(a) production of highly corrosive gases corroding
the cylinder walls and exhaust system
(b) excessive engine wear
(c) damaging of both the storage tank and the
engine
(d) deposition on engine parts
(e) excessive fuel consumption.
186. Thermal efficiency of high speed diesel engine
at design load may be of the order of
(a) 20%
(b) 35%
(c) 50%
(d) 70%
(e ) 85%.
187. The thermostat in I.C. engines permitting hot
water to go to radiator is set around
(a) 70-80°C
(b) 80-85°C
(c) 85-95°C
(d) above 100°C
(e) above 120°C.
188. The brake mean effective pressure of an I.C.
engine with increase in speed will
(a) increase
(b) decrease
(c) remain unaffected.
(d) fluctuate according to engine speed
(e) unpredictable.
189. High ash and sediment in diesel oil used in
diesel engine lead to
(a) production of highly corrosive gases corroding
the cylinder walls and ex-haust system
(b) excessive engine wear
(c) damaging of both the storage tank and the
engine
(d) deposition on engine parts
(e) blocking of exhaust pipes.
190. Mixing of fuel and air in case of dies engine
occurs in
(a) injection pump
(b) injector
(c) inlet manifold
(d) carburettor
(e) engine cylinder.
191. The advantage of reversing the flow of a in an
air cleaner is to
(a) increase velocity of air
(b) increase air flow
(c) reduce the velocity of air
(d) throw out a large percentage of foreig matter
(e) cool the air.
19 The most effective air cleaner in case diesel
engines is
(a) dry type
(b) wet type
(c) whirl type
(d) oil bath type
(e) all are equally good.
193. Fins are provided over engine cylinder
scooters for
(a) higher strength of cylinder
(b) better cooling
(c) good appearance
(d) higher efficiency
(e) easier handling and ease in manufacturing.
194. The elements of most concern in regard
pollution caused by engines are
(a) CO and C02
(b) CO and hydrocarbons
(c) C02 and hydrocarbons
(d) carbon and dust
(e) hot products of combustion
195. The preferred location of an oil cooler is
(a) before the filters
(b) after the filters
(c) between the filters
(d) before and after the filters
(e) any where.
196. The petrol from tank to the automotive ergine
is fed by
(a) gravity
(b) pump run by engine
(c) suction pressure created by, suctio stroke
(d) capillary action
(e) fuel pump.
197. In petrol engine, increase of cooling water
temperature will
(a) increase the knocking tendency
(b) decrease the knocking tendecny
(c) not affect the knocking tendency
(d) increase or decrease knocking tendency
depedning on strength and time of spark
(e) unpredictable.
207. In carburettors, the top of the fuel jet with
reference to the level in the float chamber is kept at
(a) same level
(b) slightly higher level
(c) slightly lower level
(d) may be anywhere
(e) varies from situation to situation.
208. Carburretion is done to
(a) feed petrol into cylinder
(b) govern the engine
(c) break up and mix the petrol with air
(d) heat up the charge to cylinder
(e) scavenge the cylinder.
209. Power impulses from an I.C. engine are
somoothed out by
(a) governor
(b) crank shaft
(c) gear box
(d) flywheel
(e) timing spark properly.
210. The theoretically correct mixture of air and
petrol is approximately
(a) 8 : 1
(b) 12 : 1
(c) 15 : 1
(d) 20 : 1
(e) 24: 1.
211. For low speed operation or for idling in petrol
engines, the engine requirements are for
(a) lean mixture
(b) theoretically correct mixture
(c) rich mixture
(d) any type of mixture
(e) lean/rich mixture depending upon capacity of
engine.
21 In petrol engines, advancing the spark timing will
(a) increase the knocking tendency
(b) decrease the knocking tendency
(c) not affect the knocking tendncy
(d) increase or decrease knocking tendency
depending on strenght and time of spark
(e) unpredictable.
213. The following type of carburettor is preferred
(a) concentric type
(b) eccentric type
(c) horizontal type
(d) vertical type
(e) none of the above.
214. In the passanger cars, the following type of
carburettor is preferred
(a) horizontal type
(b) downward draught type
(c) upward draught type
(c) inclined draught type
(e) any one of the above types.
215. The essential equipment for producing high
vlotage for sparking in petrol engines with battery is
(a) ignition coil
(b) ignition coil and distributor
(c) ignition coil and condenser
(d) ignition coil and contact breaker
(e) ignition coil, contact breaker and con-denser.
216. The ignition coil in diesel engines produces
voltage of the order of
(a) 6 to 12 volts
(b) 240 volts
(c) 1000 volts
(d) 20,000 volts
(e) 80,000 volts.
217. If the door of a diesel engine crankcase is
opened just after shutdown before cooling of engine,
then
(a) efficiency of engine will be poor
(b) there is a risk of explosion taking place
(c) it is the safest practice
(d) some parts may be subjected
(e) some lub oil may be wasted.
218. The thermal efficiency of a diesel engine is of
the order of
(a) 92%
(b) 68%
(c) 52%
(d) 34%
(e) 25%.
219. The thermal efficiency of a gas engine is of the
order of
(a) 92%
(b) 68%
(c) 52%
(d) 34%
(e) 25%.
220. Theoretically, the following engine should have
maximum efficiency
(a) gas engine
(b) 2-stroke S.I. engine
(c) 4-stroke S.I. engine
(d) steam engine
(e) 4-stroke C.I. engine.
221. In petrol engine using a fixed octane rating fuel
and fixed compression ratio, super charging will
(a) increase the knocking tendency
(b) decrease the knocking tendency
(c) not affect the knocking tendency
(d) increase or decrease knocking tendency
depending on strength and time of spark
(e) unpredictable.
223. High sulphur content in diesel oil used for
diesel engines leads to
(a) production of highly corrosive gases corroding
the cylinder walls and exhaust system
(b) excessive engine wear
(c) damaging of both the storage tank and the
engine
(d) deposition on engine parts
(e) reduction in thermal efficiency.
224. In open combustion chamber in diesel engines
(a) the shape and layout of the piston crown, the
inlet port, and the valve produce the turbulent effect
on fuel mixture
(b) fuel is injected into an auxiliary chamber that is
separated from the cylinder by an orifice or throat
(c) only a part of air charge is contained in an
auxiliary chamber in which the fuel starts to burn
with insufficient air which due to explosion tendency
mixes thoroughly into main cylinder charge
(d) fuel is injected at atmospheric pres¬sure
(e) there are no valves.
225. The basic requirement of a good combustion
chamber is
(a) high compression ratio
(b) low compression ratio
(c) low volumetric efficiency
(d) minimum turbulence
(e) high power output and high thermal efficiency.
226. Deposition of carbon in petrol engine cylinder
would result in increase of
(a) clearance volume
(b) swept volume
(c) compression ratio
(d) volumetric efficiency
(e) mean effective pressure.
227. Which of the following engines can work on
very lean mixture
(a) S.I. engine
(b) C.I. engine
(c) two stroke engine
(d) four stroke engine
(e) all of the above.
228. If petrol is used in a diesel engine, then
(a) higher knocking will occur
(b) efficiency will be low
(c) low power will be produced
(d) black smoke will be produced
(e) lot of fuel will remain unburnt.
229. Hot air standard diesel cycle efficiency with
increase in value of C„
(a) increases
(b) decreases
(c) remains unaffected
(d) depends on other factors
(e) unpredictable.
230. In turbulence chamber in diesel engine
(a) the shape and layout of the piston crown, the
inlet port, and the valve produce the turbulent effect
of fuel mixture
(b) fuel is injected into an auxiliary chamber that is
separated from the cylinder by an orifice or throat
(c) only a part of air charge is contained in an
auxiliary chamber in which the fuel starts to burn
with insufficient air which due to explosion tendency
mixes thoroughly into main cylinder charge
(d) there are no valves
(e) fuel is partly burnt by spark.
231. For low load operation, more suitable
(economical) engine is
(a) S.I. engine
(b) C.I. engine
(c) both are equally good
(d) multicylinder engine
(e) two stroke engine.
232. A two stroke crank compressed engine has
following ports in the cylinder
(a) suction port and exhaust port
(b) transfer port only
(c) suction port and transfer port
(d) transfer port and exhaust port
(e) suction port, exhaust port and transfer port.
233. For the same size and weight, a two stroke
engine as compared to four stroke engine will
generate power
(a) about twice
(b) about 0.5 times
(c) nearly equal
(d) about 1.7 times
(e) about 5 times.
234. A two stroke engine is usually identified by
(a) size of flywheel
(b) weight of engine
(c) type of lubrication system
(d) absence of valves
(e) location of fuel tank.
235. If diesel is fed by mistake in the oil tank of a
petrol engien, then engine will
(a) give lot of smoke
(b) detonate
(c) knock
(d) not run
(e) run for some time and then stop.
236. The thermal efficiency of a semi-diesel cycle
having fixed compression ratio and fixed quantity of
heat, with increase in pressure ratio will
(a) increase
(b) decrease
(c) remain unaffected
(d) increase/decrease depending upon engine
capacity
(e) first increase and then decrease.
245. The termal efficiency of a petrol engine at
design load is around
(a) 90%
(b) 50%
(c) 40%
(d) 30%
(e) 15%.
246. In isochronous governing, speed droop is
(a) 100%
(b) 50%
(c) 5%
(c) 30%
(e) 1%.
247. Method of governing used in petrol engine is
(a) quantity governing
(b) quality governing
(c) combined governing
(d) partial governing
(e) hit and miss governing.
248. Pick up false statement
(a) For petrol and large gas engines, quantity
governingds preferred
(b) In quantity governing, air fuel ratio is almost
constant and quantity of charge is changed
depending on load
(c) In hit and miss governing, fuel supply is
completely cut off during one or more number of
cycles
(d) In quality governing, quantity of fuel is varied to
suit the load and total charge of air is varied
(e) For close regulation of speed, combination of
both quality and quantity governing is used.
249. Method of governing used in diesel engine is
(a) quantity governing
(b) quality governing
(c) combined governing
(d) partial governing
(e) nit and miss governing.
250. An engine has a normal speed of 960 r.p.m.
and no load speed of 1000 r.p.m. The speed droop of
governor will be about
(a) 2%
(b) 4%
(c) 8%
(d)±4%
(e) 1%.

Thermodynamics Questions and Answers

Thermodynamics Questions and Answers

1. Which of the following variables controls the
physical properties of a perfect gas
(a) pressure
(b) temperature
(c) volume
(d) all of the above
(e) atomic mass.
Ans: d
2. Which of the following laws is applicable for the
behavior of a perfect gas
(a) Boyle's law
(b) Charles'law
(c) Gay-Lussac law
(d) all of the above
(e) Joule's law.
Ans: d
3. The unit of temperature in S.I. units is
(a) Centigrade
(b) Celsius
(c) Fahrenheit
(d) Kelvin
(e) Rankine.
Ans: d
4. The unit of mass in S.I. units is
(a) kilogram
(b) gram
(c) tonne
(d) quintal
(e) newton.
Ans: a
5. The unit of time in S.I. units is
(a) second
(b) minute
(c) hour
(d) day
(e) year.
Ans: a
6. The unit of length in S.I. units is
(a) meter
(b) centimeter
(c) kilometer
(d) millimeter.
Ans: a
7. The unit of energy in S.I. units is
(a) watt
(b) joule
(c) joule/s
(d) joule/m
(e) joule m.
Ans: b
8. According to Gay-Lussac law for a perfect gas,
the absolute pressure of given mass varies directly
as
(a) temperature
(b) absolute
(c) absolute temperature, if volume is kept constant
(d) volume, if temperature is kept constant
(e) remains constant,if volume and temperature are
kept constant.
Ans: c
9. An ideal gas as compared to a real gas at very
high pressure occupies
(a) more volume
(b) less volume
(c) same volume
(d) unpredictable behaviour
(e) no such correlation.
Ans: a
10. General gas equation is
(a) PV=nRT
(b) PV=mRT
(d) PV = C
(c) PV=KiRT
(e) Cp-Cv = Wj
Ans: b
11. According to Dalton's law, the total pres sure of
the mixture of gases is equal to
(a) greater of the partial pressures of all
(b) average of the partial pressures of all
(c) sum of the partial pressures of all
(d) sum of the partial pressures of all divided by
average molecular weight
(e) atmospheric pressure.
Ans: c
12. Which of the following can be regarded as gas
so that gas laws could be applicable, within the
commonly encountered temperature limits.
(a) 02, N2, steam, C02
(b) Oz, N2, water vapour
(c) S02, NH3, C02, moisture
(d) 02, N2, H2, air
(e) steam vapours, H2, C02.
Ans: d
13. The unit of pressure in S.I. units is
(a) kg/cm2
(b) mm of water column
(c) pascal
(d) dynes per square cm
(e) bars
Ans: c
14. A closed system is one in which
(a) mass does not cross boundaries of the system,
though energy may do so
(b) mass crosses the boundary but not the energy
(c) neither mass nor energy crosses the
boundaries of the system
(d) both energy and mass cross the boundaries of
the system
(e) thermodynamic reactions take place.
Ans: a
15. Temperature of a gas is produced due to
(a) its heating value
(b) kinetic energy of molecules
(c) repulsion of molecules
(d) attraction of molecules
(e) surface tension of molecules.
Ans: b
16. According to kinetic theory of gases, the
absolute zero temperature is attained when
(a) volume of the gas is zero
(b) pressure of the gas is zero
(c) kinetic energy of the molecules is zero
(d) specific heat of gas is zero
(e) mass is zero.
Ans: c
17. Kinetic theory of gases assumes that the
collisions between the molecules are
(a) perfectly elastic
(b) perfectly inelastic
(c) partly elastic
(d) partly inelastic
(e) partly elastic and partly inelastic.
Ans: a
18. The pressure'of a gas in terms of its mean
kinetic energy per unit volume E is equal to
(a) E/3
(b) E/2
(c) 3E/4
(d)2E/3
(e) 5E/4.
Ans: d
19. Kinetic energy of the molecules in terms of
absolute temperature (T) is proportional to
(a) T
(b) j
(c) J2
(d) Vr
(e) 1/Vr.
Ans: a
20. Superheated vapour behaves
(a) exactly as gas
(b) as steam
(c) as ordinary vapour
(d) approximately as a gas
(e) as average of gas and vapour.
Ans: d
21. Absolute zero pressure will occur
(a) at sea level
(b) at the center of the earth
(c) when molecular momentum of the system
becomes zero
(d) under vacuum conditions
(e) at a temperature of - 273 °K
Ans: c
22. No liquid can exist as liquid at
(a) - 273 °K
(b) vacuum
(c) zero pressure
(d) centre of earth
(e) in space.
Ans: c
23. The unit of power in S.I. units is
(a) newton
(b) pascal
(c) erg
(d) watt
(e) joule.
Ans: d
24. The condition of perfect vacuum, i.e., absolute
zero pressure can be attained at
(a) a temperature of - 273.16°C
(b) a temperature of 0°C
(c) a temperature of 273 °K
(d) a negative pressure and 0°C temperature
(e) can't be attained.
Ans: a
25. Intensive property of a system is one whose
value
(a) depends on the mass of the system, like volume
(b) does not depend on the mass of the system, like
temperature, pressure, etc.
(c) is not dependent on the path followed but on the
state
(d) is dependent on the path followed and not on the
state
(e) remains constant.
Ans: b
26. Specific heat of air at constant pressure is equal
to
(a) 0.17
(b) 0.21
(c) 0.24
(d) 1.0
(e) 1.41
Ans: c
27. Characteristic gas constant of a gas is equal to
(a) C/Cv
(b) Cv/Cp
(c) Cp - Cv
(d) Cp + Cv
(e) Cp x Cv
Ans: c
28. The behaviour of gases can be fully determined
by
(a) 1 law
(b) 2 laws
(c) 3 laws
(d) 4 laws
Ans: d
29. The ratio of two specific heats of air is equal to
(a) 0.17
(b) 0.24
(c) 0.1
(d) 1.41
(e) 2.71.
Ans: d
30. Boyle's law i.e. pV = constant is applicable to
gases under
(a) all ranges of pressures
(b) only small range of pressures
(c) high range of pressures
(d) steady change of pressures
(e) atmospheric conditions.
Ans: b
31. Which law states that the internal energy of a
gas is a function of temperature
(a) Charles' law
(b) Joule's law
(c) Regnault's law
(d) Boyle's law
(e) there is no such law.
Ans: b
32. The same volume of all gases would represent
their
(a) densities
(b) specific weights
(c) molecular weights
(d) gas characteristic constants
(e) specific gravities.
Ans: c
33. Which law states that the specific heat of a gas
remains constant at all temperatures and pressures
(a) Charles' Law
(b) Joule's Law
(c) Regnault's Law
(d) Boyle's Law
(e) there is no such law.
Ans: c
34. An open system is one in which
(a) mass does not cross boundaries of the system,
though energy may do so
(b) neither mass nor energy crosses the
boundaries of the system
(c) both energy and mass cross the boundaries of
the system
(d) mass crosses the boundary but not the energy
(e) thermodynamic reactions do not occur.
Ans: c
35. According to which law, all perfect gases
change in volume by l/273th of their original volume
at 0°C for every 1°C change in temperature when
pressure remains constant
(a) Joule's law
(b) Boyle's law
(c) Regnault's law
(d) Gay-Lussac law
(e) Charles' law.
Ans: e
36. Gases have
(a) only one value of specific heat
(b) two values of specific heat
(c) three values of specific heat
(d) no value of specific heat
(e) under some conditions one value and
sometimes two values of specific heat.
Ans: b
37. According to Avogadro's Hypothesis
(a) the molecular weights of all the perfect gases
occupy the same volume under same conditions of
pressure and temperature
(b) the sum of partial pressure of mixture of two
gases is sum of the two
(c) product of the gas constant and the molecular
weight of an ideal gas is constant
(d) gases have two values of specific heat
(e) all systems can be regarded as closed systems.
Ans: a
38. Extensive property of a system is one whose
value
(a) depends on the mass of the system like volume
(b) does not depend on the mass of the system, like
temperature, pressure, etc.
(c) is not dependent on the path followed but on the
state
(d) is dependent on the path followed and not on the
state
(e) is always constant.
Ans: a
39. Work done in a free expansion process is
(a) + ve
(b) -ve
(c) zero
(d) maximum
(e) minimum.
Ans: c
40. The statement that molecular weights of all
gases occupy the same volume is known as
(a) Avogadro's hypothesis
(b) Dalton's law
(c) Gas law
(d) Law of thermodynamics
(e) Joule's law.
Ans: a
41. To convert volumetric analysis to gravimetric
analysis, the relative volume of each constituent of
the flue gases is
(a) divided by its molecular weight
(b) multiplied by its molecular weight
(c) multiplied by its density
(d) multiplied by its specific weight
(e) divided by its specific weight.
Ans: b
42. If a gas is heated against a pressure, keeping
the volume constant, then work done will be equal
to
(a) + v
(b) - ve
(c) zero
(d) pressure x volume
(e) any where between zero and infinity.
Ans: c
43. An isolated system is one in which
(a) mass does not cross boundaries of the system,
though energy may do so
(b) neither mass nor energy crosses the
boundaries of the system
(c) both energy and mass cross the boundaries of
the system
(d) mass crosses the boundary but not the energy
(e) thermodynamic reactions do not occur.
Ans: b
44. Properties of substances like pressure,
temperature and density, in thermodynamic
coordinates are
(a) path functions
(b) point functions
(c) cyclic functions
(d) real functions
(e) thermodynamic functions.
Ans: b
45. Which of the following quantities is not the
property of the system
(a) pressure
(b) temperature
(c) specific volume
(d) heat
(e) density.
Ans: d
46. According to Avogadro's law, for a given
pressure and temperature, each molecule of a gas
(a) occupies volume proportional to its molecular
weight
(b) occupies volume proportional to its specific
weight
(c) occupies volume inversely proportional to its
molecular weight
(d) occupies volume inversely proportional to its
specific weight
(e) occupies same volume.
Ans: e
47. Mixture of ice and water form a
(a) closed system
(b) open system
(c) isolated system
(d) heterogeneous system
(e) thermodynamic system.
Ans: d
48. Which of the following is the property of a
system
(a) pressure and temperature
(b) internal energy
(c) volume and density
(d) enthalpy and entropy
(e) all of the above.
Ans: e
49. On weight basis, air contains following parts of
oxygen
(a) 21
(b) 23
(c) 25
(d) 73
(e) 79.
Ans: b
50. Which of the following is not the intensive
property
(a) pressure
(b) temperature
(c) density
(d) heat
(e) specific volume.
Ans: d
51. Which of the following items is not a path
function
(a) heat
(b) work
(c) kinetic energy
(d) vdp
(e) thermal conductivity.
Ans: e
52. Work done in an adiabatic process between a
given pair of end states depends on
(a) the end states only
(b) particular adiabatic process
(c) the value of index n
(d) the value of heattransferred
(e) mass of the system.
Ans: a
53. Heat and work are
(a) point functions
(b) system properties
(c) path functions
(d) intensive properties
(e) extensive properties.
Ans: c
54. Which of the following parameters is constant
for a mole for most of the gases at a given
temperature and pressure
(a) enthalpy
(b) volume
(c) mass
(d) entropy
(e) specific volume.
Ans: b
55. The value of n = 1 in the polytropic process
indicates it to be
(a) reversible process
(b) isothermal process
(c) adiabatic process
(d) irreversible process
(e) free expansion process.
Ans: b
56. Solids and liquids have
(a) one value of specific heat (ft) two values of
specific heat
(c) three values of specific heat
(d) no value of specific heat
(e) one value under some conditions and two
values under other conditions.
Ans: a
57. A perfect gas at 27°C is heated at constant
pressure till its volume is double. The final
temperature is
(a) 54°C
(b) 327°C
(c)  108°C
(d) 654°C
(e) 600°C
Ans: b
58. Curve A in Fig. 1.1 compared to curves B and C
shows the following type of expansion
(a) pV"=C
(b) isothermal
(c) adiabatic
(d) free expansion
(e) throttling.
Ans: b
59. If value of n is infinitely large in a polytropic
process pV" = C, then the process is known as
constant
(a) volume
(b) pressure
(c) temperature
(d) enthalpy
(e) entropy.
Ans: a
60. The index of compression n tends to reach ratio
of specific heats y when
(a) flow is uniform and steady
(b) process is isentropic
(c) process is isothermal
(d) process is isentropic and specific heat does not
change with temperature
(e) process is isentropic and specific heat changes
with temperature.
Ans: d
61. Change in enthalpy of a system is the heat
supplied at
(a) constant pressure
(b) constant temperature
(c) constant volume
(d) constant entropy
(e) N.T.P. condition.
Ans: a
62. The term N.T.P. stands for
(a) nominal temperature and pressure
(b) natural temperature and pressure
(c) normal temperature and pressure
(d) normal thermodynamic practice
(e) normal thermodynamic pressure.
Ans: c
63. A heat exchange process in which the product of
pressure and volume remains constant is known as
(a) heat exchange process
(b) throttling process
(c) isentropic process
(d) adiabatic process
(e) hyperbolic process.
Ans: e
64. In an isothermal process, the internal energy of
gas molecules
(a) increases
(b) decreases
(c) remains constant
(d) may increase/decrease depending on the
properties of gas
(e) shows unpredictable behaviour.
Ans: c
65. Zeroth law of thermodynamics
(a) deals with conversion of mass and energy
(b) deals with reversibility and irreversibility of
process
(c) states that if two systems are both in
equilibrium with a third system, they are in thermal
equilibrium with each other
(d) deals with heat engines
(e) does not exist.
Ans: c
66. If a certain amount of dry ice is mixed with
same amount of water at 80°C, the final
temperature of mixture will be
(a) 80°C
(b) 0°C
(c) 40°C
(d) 20°C
(e) 60°C.
Ans: b
67. The basis for measuring thermodynamic
property of temperature is given by
(a) zeroth law of thermodynamics
(b) first law of thermodynamics
(c) second law of thermodynamics
(d) third law of thermodynamics
(e) Avogadro's hypothesis.
Ans: a
68. One watt is equal to
(a) 1 Nm/s
(b) 1 N/mt
(c) 1 Nm/hr
(d) 1 kNm/hr
(e) 1 kNm/mt.
Ans: a
69. Work done is zero for the following process
(a) constant volume
(b) free expansion
(c) throttling
(d) all Of the above
(e) none of the above.
Ans: d
70. For which of the following substances, the gas
laws can be used with minimum error
(a) dry steam
(b) wet steam
(c) saturated steam
(d) superheated steam
(e) steam at atmospheric pressure.
Ans: d
71. In a non-flow reversible process for which p =
(- 3V+ 15) x 105N/m2,V changes from 1 m to 2
m3. The work done will be about
(a) 100 xlOO5 joules
(b) lxlO5 joules
(c) 10 xlO5 joules
(d) 10 xlO5 kilo joules
(e) 10xl04ki\ojoules.
Ans: c
72. The value of the product of molecular weight and
the gas characteristic constant for all the gases in
M.K.S. unit is
(a) 29.27 kgfm/mol°K
(b) 8314kgfm/mol°K
(c) 848kgfm/mol°K
(d) 427kgfm/mol°K
(e) 735 kgfm/mol°K.
Ans: c
73. On volume basis, air contains following parts of
oxygen
(a) 21
(b) 23
(c) 25
(d) 77
(e) 79.
Ans: a
74. Universal gas constant is defined as equal to
product of the molecular weight of the gas and
(a) specific heat at constant pressure
(b) specific heat at constant volume
(c) ratio of two specific heats
(d) gas constant
(e) unity.
Ans: d
75. The value of the product of molecular weight and
the gas characteristic constant for all the gases in
S.I. units is
(a) 29.27 J/kmol°K
(b) 83.14J/kmol°K
(c) 848J/kmol°K
(d) All J/kmol °K
(e) 735 J/kmol °K.
Ans: b
76. For which of the following substances, the
internal energy and enthalpy are the functions of
temperature only
(a) any gas
(b) saturated steam
(c) water
(d) perfect gas
(e) superheated steam.
Ans: d
77. In a free expansion process
(a) work done is zero
(b) heat transfer is zero
(c) both (a) and (b) above
(d) work done is zero but heat increases
(e) work done is zero but heat decreases.
Ans: c
78. If a gas vapour is allowed to expand through a
very minute aperture, then such a process is known
as
(a) free expansion
(b) hyperbolic expansion
(c) adiabatic expansion
(d) parabolic expansion
(e) throttling.
Ans: e
79. The specific heat of air increases with increase
in
(a) temperature
(b) pressure
(c) both pressure and temperature
(d) variation of its constituents
(e) air flow
Ans: a
80. If a fluid expands suddenly into vacuum through
an orifice of large dimension, then such a process is
called
(a) free expansion
(b) hyperbolic expansion
(c) adiabatic expansion
(d) parabolic expansion
(e) throttling.
Ans: a
81. Which of the following processes are
thermodynamically reversible
(a) throttling
(b) free expansion
(c) constant volume and constant pressure
(d) hyperbolic and pV = C
(e) isothermal and adiabatic.
Ans: e
82. Which of the following processes is irreversible
process
(a) isothermal
(b) adiabatic
(c) throttling
(d) all of the above
(e) none of the above.
Ans: c
83. In order that a cycle be reversible, following
must be satisfied
(a) free expansion or friction resisted expansion/
compression process should not be encountered
(b) when heat is being absorbed, temperature of hot
source and working sub¬stance should be same
(c) when beat is being rejected, temperature of cold
source and working sub-stance should be same
(d) all of the above
(e) none of the above.
Ans: d
84. For a thermodynamic process to be reversible,
the temperature difference between hot body and
working substance should be
(a) zero
(b) minimum
(d) maximum
(d) infinity
(e) there is no such criterion.
Ans: a
85. Minimum work in compressor is possible when
the value of adiabatic index n is equal to
(a) 0.75
(b) 1
(c) 1.27
(d) 1.35
(e) 2.
Ans: b
86. Molecular volume of any perfect gas at 600 x
103 N/m2 and 27°C will be
(a) 4.17m3/kgmol
(b) 400 m3/kg mol
(c) 0.15 m3/kg mol
(d) 41.7 m3/kg mol
(e) 417m3/kgmol.
Ans: a
87. A gas is compressed in a cylinder by a movable
piston to a volume one-half its original volume.
During the process 300 kJ heat left the gas and
internal energy remained same. The work done on
gas in Nm will be
(a) 300 Nm
(b) 300,000 Nm
(c) 30 Nm
(d) 3000 Nm
(e) 30,000 Nm.
Ans: b
88. The more effective way of increasing efficiency
of Carnot engine is to
(a) increase higher temperature
(b) decrease higher temperature
(c) increase lower temperature
(d) decrease lower temperature
(e) keep lower temperature constant.
Ans: d
89. Entropy change depends on
(a) heat transfer
(b) mass transfer
(c) change of temperature
(d) thermodynamic state
(e) change of pressure and volume.
Ans: a
90. For reversible adiabatic process, change in
entropy is
(a) maximum
(b) minimum
(c) zero
(d) unpredictable
(e) negative.
Ans: c
91. Isochoric process is one in which
(a) free expansion takes place
(b) very little mechanical work is done by the
system
(c) no mechanical work is done by the system
(d) all parameters remain constant
(e) mass and energy transfer do not take place.
Ans: c
92. According to first law of thermodynamics
(a) work done by a system is equal to heat
transferred by the system
(b) total internal energy of  a system during a
process remains constant
(c) internal energy, enthalpy and entropy during a
process remain constant
(d) total energy of a system remains constant
(e) entropy of a system remains constant.
Ans: d
93. Energy can neither be created nor destroyed but
can be converted from one form to other is inferred
from
(a) zeroth low of thermodynamic
(b) first law of thermodynamics
(c) second law to thermodynamics
(d) basic law of thermodynamics
(e) claussius statement.
Ans: b
94. First law of thermodynamics furnishes the
relationship between
(a) heat and work
(b) heat, work and properties of the system
(c) various properties of the system
(d) various thermodynamic processes
(e) heat and internal energy.
Ans: b
95. Change in enthalpy in a closed system is equal
to heat transferred if the reversible process takes
place at constant
(a) pressure
(b) temperature
(c) volume
(d) internal energy
(e) entropy.
Ans: a
96. In an isothermal process, the internal energy
(a) increases
(b) decreases
(c) remains constant
(d) first increases and then decreases
(e) first decreases and then increases.
Ans: c
97. Change in internal energy in a closed system is
equal to heat transferred if the reversible process
takes place at constant
(a) pressure
(b) temperature
(c) volume
(d) internal energy
(e) entropy.
Ans: c
98. According to first law of thermodynamics
(a) mass and energy are mutually convertible
(b) Carnot engine is most efficient
(c) heat and work are mutually convertible
(d) mass and light are mutually convertible
(e) heat flows from hot substance to cold
substance.
Ans: c
99. Total heat of a substance is also known as
(a) internal energy
(b) entropy
(c) thermal capacity
(d) enthalpy
(e) thermalconductance.
Ans: d
100. First law of thermodynamics
(a) enables to determine change in internal energy
of the system
(b) does not help to predict whether the system will
or not undergo a change
(c) does not enable to determine change in entropy
(d) provides relationship between heat, work and
internal energy
(e) all of the above.
Ans: e
101. Addition of heat at constant pressure to a gas
results in
(a) raising its temperature
(b) raising its pressure
(c) raising its volume
(d) raising its temperature and doing external work
(e) doing external work.
Ans: d
102. Carnot cycle has maximum efficiency for
(a) reversible engine
(b) irreversible engine
(c) new engine
(d) petrol engine
(e) diesel engine.
Ans: a
103. Measurement of temperature is based on
(a) thermodynamic properties
(b) zeroth law of thermodynamics
(c) first law of thermodynamics
(d) second law of thermodynamics
(e) joule's law.
Ans: b
104. Carnot cycle efficiency depends upon
(a) properties of the medium/substance used
(b) condition of engine
(c) working condition
(d) temperature range of operation
(e) effectiveness of insulating material around the
engine.
Ans: d
105. Carnot cycle efficiency is maximum when
(a) initial temperature is 0°K
(b) final temperature is 0°K
(c) difference between initial and final temperature
is 0°K
(d) final temperature is 0°C
(e) initial temperature is minimum possible.
Ans: b
106. An engine operates between temperatures of
900°Kandr2 and another engine between T2 and
400°K For both to do equal work, value of T2 will be
(a) 650°K
(b) 600°K
(c) 625°K
(d) 700°K
(e) 750°K.
Ans: a
107. If heat be exchanged in a reversible manner,
which of the following property of the working
substance will change accordingly
(a) temperature
(b) enthalpy
(c) internal energy
(d) entropy
(e) all of the above.
Ans: d
108. If a system after undergoing a series of
processes, returns to the initial state then
(a) process is thermodynamically in equilibrium
(b) process is executed in closed system cycle
(c) its entropy will change due to irreversibility
(d) sum of heat and work transfer will be zero
(e) no work will be done by the system.
Ans: d
109. Which of the following represents the perpetual
motion of the first kind
(a) engine with 100% thermal efficiency
(b) a fully reversible engine
(c) transfer of heat energy from low temperature
source to high temperature source
(d) a machine that continuously creates its own
energy
(e) production of energy by temperature differential
in sea water at different levels.
Ans:
110. An actual engine is to be designed having
same efficiency as the Carnot cycle. Such a
proposition is
(a) feasible
(b) impossible
(c) possible
(d) possible, but with lot of sophistications
(e) desirable.
Ans: d
112. A manufacturer claims to have a heat engine
capable of developing 20 h.p. by receiving heat input
of 400 kcal/mt and working between the
temperature limits of 227° C and 27° C. His claim is
(a) justified
(b) not possible
(c) may be possible with lot of sophistications
(d) cost will be very high
(e) theroretically possible.
Ans: b
113. In a Carnot cycle, heat is transferred at
(a) constant pressure
(b) constant volume
(c) constant temperature
(d) constant enthaply
(e) any one of the above.
Ans: c
114. A diathermic wall is one which
(a) prevents thermal interaction
(b) permits thermal interaction
(c) encourages thermal interaction
(d) discourages thermal interaction
(e) does not exist.
Ans: b
115. An adiabatic wall is one which
(a) prevents thermal interaction
(b) permits thermal interaction
(c) encourages thermal interaction
(d) discourages thermal interaction
(e) dos not exist.
Ans: a
116. The door of a running refrigerator inside a
room was left open. Which of the following
statements is correct?
(a) The room will be cooled to the temperature
inside the refrigerator.
(b) The room will be cooled very slightly.
(c) The room will be gradually warmed up.
(d) The temperature of the air in room will remain
unaffected.
(e) any one of above is possible depending on the
capacity.
Ans: c
117. Compressed air coming out from a punctured
football
(a) becomes hotter
(b) becomes cooler1
(c) remains at the same temperature
(d) may become hotter or cooler depend-ing upon
the humidity of the surround¬ing air
(e) attains atmospheric temperature.
Ans: b
118. Water contained in a beaker can be made to
boil by passing steam through it
(a) at atmospheric pressure
(b) at a pressure below the firuosphejric pressure
(c) at a pressure greater than atmospheric
pressure
(d) any pressure
(e) not possible.
Ans: c
119. During throttling process
(a) heat exchange does not take place
(b) no work is done by expanding steam
(c) there is no change of internal energy of steam
(d) all of the above
(e) entropy decreases.
Ans: d
120. The energy of molecular motion appears as
(a) heat
(b) potential energy
(c) surface tension
(d) friction
(e) increase in pressure.
Ans: a
121. A sudden fall in the barometer reading is a
sign of approaching
(a) fine weather
(b) rains
(c) storm
(d) cold wave
(e) hot wave.
Ans: c
122. The unit'of universal gas constant is
(a) watts/°K
(b) dynes/°C
(c) ergscm/°K
(d)erg/°K
(e) none of the above.
Ans: d
123. Calorie is a measure of
(a) specific heat
(b) quantity of heat
(c) thermal capacity
(d)entropy
(e) work.
Ans: b
124. I kgf/cm2 is equal to
(a) 760 mm Hg
(b) zero mm Hg
(c) 735.6 mm Hg
(d) 1 mm Hg
(e) lOOmmHg.
Ans: c
125. Barometric pressure is equal to
(a) 760 mm Hg
(b) zero mm Hg
(c) 735.6 mm Hg
(d) 1 mm Hg
(e) 100mm Hg.
Ans: a
126. One barometric pressure or 1 atmospheric
pressure is equal to
(a) 1 kgf/cnr2
(b) 1.033 kgf/cm2
(c) 0 kgf/cm2
(d) 1.0197 kgf/cm2
(e) 100 kgf/cm2.
Ans: b
127. The first law of thermodynamics is the law of
(a) conservation of mass
(b) conservation of energy
(c) conservation of momentum
(d) conservation of heat
(e) conservation of temperature.
Ans: b
128. A perpetual motion machine is
(a) a thermodynamic machine
(b) a non-thermodynamic machine
(c) a hypothetical machine
(d) a hypothetical machine whose opera-tion would
violate the laws of thermodynamics
(e) an inefficient machine.
Ans: d
129. Kelvin Planck's law deals with
(a) conservation of heat
(b) conservation of work
(c) conversion of heat into work
(d) conversion fo work into heat
(e) conservation of mass.
Ans: c
130. According to Clausis statement of second law
of thermodynamics
(a) heat can't be transferred from low temperature
source to high temperature source
(b) heat can be transferred for low temperature to
high temperature source by using refrigeration
cycle.
(c) heat can be transferred from low temperature to
high temperature source if COP of process is more
than unity
(d) heat can't be transferred from low temperature
to high temperature source without the aid of
external energy
(e) all of the above.
Ans: d
131. Thermal power plant works on
(a) Carnot cycle
(b) Joule cycle
(d) Rankine cycle
(d) Otto cycle
(e) Brayton cycle.
Ans: c
132. Which of the following is an irreversible cycle
(a) carnot
(b) Stirling
(c) ericsson
(d) all of the above
(e) none of the above.
Ans: e
133. Otto cycle consists of following four processes
(a) two isothermals and two isentropics
(b) two isentropics and two constant volumes
(c) two isentropics, one constant volume and one
constant pressure
(d) two isentropics and two constant pres-sures
(e) none of the above.
Ans: b
134. The efficiency of a Carnot engine depends on
(a) working substance
(b) design of engine
(c) size of engine
(d) type of fuel fired
(e) temperatures of source and sink.
Ans: e
135. For same compression ratio and for same heat
added
(a) Otto cycle is more efficient than Diesel cycle
(b) Diesel cycle is more efficient than Otto cycle
(c) efficiency depends on other factors
(d) both Otto and Diesel cycles are equally efficient
(e) none of the above.
Ans: a
136. The efficiency of Carnot cycle is maximum for
(a) gas engine
(b) well lubricated engine
(c) petrol engine
(d) steam engine
(e) reversible engine.
Ans: e
137. Carnot cycle is
(a) a reversible cycle (ft) an irreversible cycle
(c) a semi-reversible cycle
(d) a quasi static cycle
(e) an adiabatic irreversible cycle.
Ans: a
138. Diesel cycle consists of following four
processes
(a) two isothermals and two isentropics
(b) two isentropics, and two constant volumes.
(c) two isentropics, one constant volume and one
constant pressure
(d) two isentropics and two constant pressures
(e) none of the above.
Ans: c
139. If both Stirling and Carnot cycles operate within
the same temperature limits, then efficiency of
Stirling cycle as compared to Carnot cycle
(a) more
(b) less
(c) equal
(d) depends on other factors
(e) none of the above.
Ans: c
140. Stirling and Ericsson cycles are
(a) reversible cycles
(b) irreversible cycles
(c) quasi-static cycles
(d) semi-reversible cycles
(e) adiabatic irreversible cycles.
Ans: a
141. A cycle consisting of two adiabatics and two
constant pressure processes is known as
(a) Otto cycle
(b) Ericsson cycle
(c) Joule cycle
(d) Stirling cycle
(e) Atkinson cycle.
Ans: c
142. Reversed joule cycle is called
(a) Carnot cycle
(b) Rankine cycle
(c) Brayton cycle
(d) Bell Coleman cycle
(e) Dual cycle.
Ans: c
143. Brayton cycle consists' of following four
processes
(a) two isothermals and two isentropics
(b) two isentropics and two constant volumes
(c) two isentropics, one constant volume and one
constant pressure
(d) two isentropics and two constant pres-sures
(e) none of the above.
Ans: d
144. Which of the following cycles is not a
reversible cycle
(a) Carnot
(b) Ericsson
(c) Stirling
(d) Joule
(e) none of the above.
Ans: e
145. The cycle in which heat is supplied at constant
volume and rejected at constant pressure is known
as
(a) Dual combustion cycle
(b) Diesel cycle
(c) Atkinson cycle
(d) Rankine cycle
(e) Stirling cycle.
Ans: c
146. The efficiency of Diesei cycle with decrease in
cut off
(a) increases
(b) decreases
(c) remains unaffected
(d) first increases and then decreases
(e) first decreases and then increases.
Ans: a
147. Which of the following cycles has maximum
efficiency
(a) Rankine
(b) Stirling
(c) Carnot
(d) Brayton
(e) Joule.
Ans: c
148. The ideal efficiency of a Brayton cycle without
regeneration with increase ni pressure ratio will
(a) increase
(b) decrease
(c) remain unchanged
(d) increase/decrease depending  on application
(e) unpredictable.
Ans: a
149. The ideal efficiency of a Brayton cycle with
regeneration, with increase in pressure ratio will
(a) increase
(b) decrease
(c) remain unchanged
(d) increase/decrease depending on ap-plication
(e) unpredictable. "
Ans: b
150. The following cycle is used for air craft
refrigeration
(a) Brayton cycle
(b) Joule cycle
(c) Carnot cycle
(d) Bell-Coleman cycle
(e) Reversed-Brayton cycle.
Ans: e
151. Gas turbine cycle consists of
(a) two isothermals and two isentropics
(b) two isentropics and two constant volumes
(c) two isentropics, one constant volume and one
constant pressure
(d) two isentropics and two constant pressures
(e) none of the above.
Ans: d
152. The thermodynamic difference between a
Rankine cycle working with saturated steam and the
Carnot cycle is that
(a) carnot cycle can't work with saturated steam
(b) heat is supplied to water at temperature below
the maximum temperature of the cycle
(c) a rankine cycle receives heat at two places
(d) rankine cycle is hypothetical
(e) none of the above.
Ans: b

Latest Machine Design Questions and Answers

Machine Design Questions and Answers

1. The ultimate strength of steel in tension in
comparison to shear is in the ratio of
(a) 1 : l
(b) 2:1
(c) 3 : 2
(d) 2 : 3
(e) 1 : 2
Ans: c
2. The permissible stress for carbon steel under
static loading is generally taken as
(a) 2000-3000 kg/pm2
(b) 3000-4000 kg/cm2
(c) 4000-4500 kg/cm2
(d) 7500-10,000 kg/cm2
(e) 10,000-15,000 kg/cm2.
Ans: c
3. The property of a material which enables it to
resist fracture due to high impact loads is known as
(a) elasticity
(b) endurance
(c) strength
(d) toughness
(e) resilience.
Ans: d
4. A hot short metal is
(a) brittle when cold
(b) brittle when hot
(c) brittle under all conditions
(d) ductile at high temperature
(e) hard when hot.
Ans: b
5. Guest's theory of failure is applicable for
following type of materials
(a) brittle
(b) ductile
(c) elastic
(d) plastic
(e) tough.
Ans: b
6. Rankine's theory of failure is applicable for
following type of materials
(a) brittle
(b) ductile
(c) elastic
(d) plastic
(e) tough.
Ans: a
7. If an unsupported uniform cross sectional elastic
bar is subjected to a longitudinal impact from a rigid
bob moving with velocity v, then a compressive
wave of intensity sc is propagated through the bar
as follows
(a) vpE
(b) vVvF
(c) WpE/2
(d) IvHpE
(e) none of the above, where E = modulus of
elasticity and p = mass density.
Ans: a
8. Tensile strength of a mild steel specimen can be
roughly predicted from following hardness test
(a) Brinell
(b) Rockwell
(c) Vicker
(d) Shore's sceleroscope
(e) none of the above.
Ans: a
9. Resilience of a material is important, when it is
subjected to
(a) combined loading
(b) fatigue
(c) thermal stresses
(d) wear and tear
(e) shock loading.
Ans: e
10. In the case of an elastic bar fixed at upper end
and loaded by a falling weight at lower end, the
shock load produced can be decreased by
(a) decreasing the cross-section area of' bar
(b) increasing the cross-section area of bar
(c) remain unaffected with cross-section area
(d) would depend upon other factors
(e) none of the above.
Ans: a
11. .Other method of reducing shock load in the
above case can be
(a) to decrease length
(b) to increase length
(c) unaffected by length
(d) other factors would decide same
(e) none of the above.
Ans: b
12. If a load W is applied instantaneously on a bar;
then the stress induced in bar will
(a) be independent of ratio of mass of load W to
mass of bar (y)
(b) increase with increase in y
(c) decrease with decrease in y
(d) depend on other considerations
(e) none of the above.
Ans: a
13. Brittle coating technique is used for
(a) determining brittleness
(b) protecting metal against corrosion
(c) protecting metal against wear and tear
(d) experimental stress analysis
(e) non-destructive testing of metals.
Ans: d
14. Stress concentration is caused due to
(a) variation in properties of material from point to
point in a member
(b) pitting at'points or areas at which loads on a
member are applied
(c) abrupt change of section
(d) all of the above
(e) none of the above.
Ans: d
15. The endurance limit of a material with finished
surface in comparison to rough surface is
(a) more
(b) less
(c) same
(d) more or less depending on quantum of load
(e) unpredictable.
Ans: a
16. Plastic flow in ductile materials
(a) increases the seriousness of static load-ing
stress concentration
(b) lessens the seriousness of static load¬ing
stress concentration
(c) has no effect on it
(d) depends on other considerations
(e) none of the above.
Ans: b
17. The maximum stress due to stress
concentration in a bar having circular transverse
hole, as compared to its static
stress without hole will be
(a) same in both cases
(b) 2 times more
(c) 3 times more
(d) 4 times more
(e) unpredictable.
Ans: c
18. The fatigue life of a part can be improved by
(a) electroplating
(b) polishing
(c) coating
(d) shot peening
(e) heat treating.
Ans: d
19. Stress concentration in static loading is more
serious in
(a) ductile materials
(b) brittle materials
(c) equally serious in both cases
(d) depends on other factors
(e) unpredictable.
Ans: b
20. Stress concentration in cyclic loading is more
serious in
(a) ductile materials
(b) brittle materials
(c) equally serious in both cases
(d) depends on other factors
(e) unpredictable.
Ans: a
21. Endurance limit or fatigue limit is the maximum
stress that a member can withstand for an infinite
number of load applications without failure when
subjected to
(a) dynamic loading
(b) static loading
(c) combined static and dynamic loading
(d) completely reversed loading
(e) all of the above.
Ans: d
22. Pick up wrong statement. Fatigue strength can
be increased by
(a) cold working
(b) shot peening
(c) grinding and lapping surface
(d) hot working
(e) using gradual changes of section.
Ans: d
23. Which of the following is not correct procedure
to increase the fatigue limit
(a) cold working
(b) shot peening
(c) surface decarburisation
(d) under-stressing
(e) all of the above.
Ans: c
24. Coaxing is the procedure of increasing
(a) metal strength by cycling
(b) metal hardness by surface treatment
(c) metal resistance to corrosion by coating
(d) fatigue limit by overstressing the metal by
successively increasing loadings
(e) none of the above.
Ans: d
25. Which is correct statement ?
Stress concentration in static loading is
(a) very serious in brittle materials and less serious
in ductile materials
(b) very serious in ductile materials and less
serious in brittle materials
(c) equally serious in both types of materials
(d) seriousness would depend on other factors
(e) none of the above.
Ans: a
26. The notch angle of the Izod impact test
specimen is
(a) 10°
(b) 20°
(c) 30°
(d) 45°
(e) 60°.
Ans: d
27. In Vicker's hardness testing, the pyramid
indentor apex is
(a) 40°
(b) 122°
(c) 136°
(d) 152°
(e) 161°.
Ans: c
28. Which is correct statement ?
Stress concentration in cyclic loading is
(a) very serious in brittle materials and less
serious in ductile materials
(b) very serious in ductile materials and less
serious in brittle materials
(c) equally serious in both types of materials
(d) seriousness would depend on other factors
(e) none of the above.
Ans: c
29. In testing a material for endurance strength, it is
subjected to
(a) static load
(b) dynamic load
(c) impact load
(d) static as well as dynamic load
(e) completely reversed load.
Ans: e
30. If a material fails below its yield point, failure
would be due to
(a) straining
(b) fatigue
(c) creep
(d) sudden loading
(e) impact loading.
Ans: b
31. The fatigue limit of a material
(a) is greatly decreased by poor surface conditions
(b) remains same irrespective of surface conditions
(c) depends mainly on core composition
(d) is dependent upon yield strength of material
(e) none of the above.
Ans: a
32. Cold working
(a) increases the fatigue strength
(b) decreases the fatigue strength
(c) has no influence on fatigue strength
(d) alone has no influence on fatigue strength
(e) none of the above.
Ans: a
33. Yield point in fatigue loading as compared to
static loading is
(a) same
(b) higher
(c) lower
(d) depends on other factors
(e) none of the above.
Ans: c
34. Residual stress in materials
(a) acts when external load is applied
(b) becomes zero when external load is removed
(c) is independent of external loads
(d) is always harmful
(e) is always beneficial.
Ans: c
35. The building up of worn and uridersized parts,
subjected to repeated loads by electroplating is
(a) best method
(b) extremely hazardous
(c) has no effect as regards fatigue strength
(d) cheapest method
(e) all of the above.
Ans: a
36. In nitrated parts, the origins of the fatigue
cracks will occur at
(a) surface
(b) just below the surface
(c) within the core
(d) could occur anywhere
(e) none of the above.
Ans: e
37. Which process will increase the fatigue duration
of parts ?
(a) finishing and polishing
(b) shot-peening
(c) decarburisation
(d) electroplating
(e) all of the above".
Ans: b
38. Which is correct statement ?
(a) a member made of steel will generally be more
rigid than a member of equal load-carrying ability
made of cast iron
(b) a member made of cast iron will generally be.
more rigid than a member of equal load carrying
ability made of steel
(c) both will be equally rigid
(d) which one is rigid will depend on several other
factors
(e) none of the above.
Ans: b
39. Resistance to fatigue of a material is measured
by
(a) Young's modulus
(b) coefficient of elasticity
(c) elastic limit
(d) ultimate tensile strength
(e) endurance limit.
Ans: e
40. In most machine members, the damping
capacity of the material should be
(a) low
(b) zero
(c) high
(d) could be anything
(e) none of the above.
Ans: c
41. The ratio of endurance limit in shear to the
endurance limit in flexure is
(a) 0.33
(b) 0.4
(c) 0.5
(d) 0.55
(e) 0.6
Ans: d
42. For steel, the ultimate strength in shear as
compared to ultimate strength in tension is
(a) same
(b) 1/2
(c) 1/3
(d) 1/4
(e) 2/3
Ans: e
43. The endurance limit in shear of carbon steel can
be obtained by multiplying the endurance limit in
flexure by a factor of
(a) 0.25
(b) 0.45
(r) 0.55
(d) 0.65
(e)0.75.
Ans: e
44. At low temperatures (say 75°C) the notched-bar
impact value of steel
(a) increases markedly
(b) decreases markedly
(c) remains same
(d) depends on heat treatment carried out
(e) none of the above.
Ans: b
45. A bolt
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part to be joined
(c) has both the ends threaded
(d) is provided with pointed threads
(e) requires no nut.
Ans: a
46. The crest diameter of a screw thread is same
as
(a) major diameter
(b) minor diameter
(c) pitch diameter
(d) core diameter
(e) none of the above.
Ans: a
47. If d is the diameter of bolt hole then for a
flanged pipe joint to be leak proof, the
circumferential pitch of the bolts should be
(a) lOVZ
(b) 10VZtol5Vd
(c) 15Vdto20VZ
(d) 20Vdto30Vd
(e) 30V5"to40Vd.
Ans: d
48. Maximum principal stress theory is applicable
for
(a) ductile materials
(b) brittle materials
(c) elastic materials
(d) all of the above
(e) none of the above.
Ans: b
49. The following type of nut is used with alien bolt
(a) alien nut
(b) hexagonal nut
(c) slotted nut
(d) castle nut
(e) any one of the above.
Ans: e
50. A stud
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part to be joined
(c) has both the ends threaded
(d) has pointed threads
(e) requires locking nuts.
Ans: c
51. Shear stress theory is applicable for
(a) ductile fnaterials
(b) brittle materials
(c) elastic materials
(d) all of the above
(e) none of the above.
Ans: a
52. A tap bolt
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part \o be joined
(c) has both the ends threaded
(d) has pointed threads
(e) requires locking devices.
Ans: b
53. For applications involving high stresses in one
direction only the following type of thread would be
best suited
(a) ISO metric thread
(b) acme thread
(c) square thread
(d) buttress thread
(e) British Association thread.
Ans: d
54. The included angle in unified of American
National threads is
(a) 60°
(b) 55°
(c) 47°
(d) 29°
(e) none of the above.
Ans: a
55. The function of a washer is to
(a) provide cushioning effect
(b) provide bearing area
(c) absorb shocks and vibrations
(d) provide smooth surface in place of rough
surface
(e) act as a locking device.
Ans: b
56. Cap screws are
(a) similar to'small size tap bolts except that a
greater variety of shapes of heads are available
(b) slotted for a screw driver and generally used
with a nut
(c) used to prevent relative motion be-tween parts
(d) provided with detachable caps
(e) similar to stud.
Ans: a
57. An alien bolt is
(a) self locking bolt
(b) same as stud
(c) provided with hexagonal depression in head
(d) used in high speed components
(e) provided with countersunk head.
Ans: c
58. The deflection of a cantilever beam under load W
is 8. If its width is halved, then the deflection under
load W will be
(a) 28
(b) 8/2
(c) 48
(d) 8/4
(e) none of the above.
Ans: c
59. Ball bearing type screws are found in following
application
(a) screw jack
(b) aeroplane engines
(c) crane
(d) steering mechanism
(e) bench vice.
Ans: d
60. Set screws are
(a) similar to small size tap bolts except that a
greater variety of shapes of heads are available
(b) slotted for a screw driver and generally used
with a nut
(c) used to prevent relative motion be-tween parts
(d) similar to stud
(e) none of the above.
Ans: c
61. A self locking screw has
(a) fine threads
(b) coarse threads
(c) coefficient of friction > tangent of load angle
(d) hole for inserting split pin
(e) two nuts for locking.
Ans: c
62. The designation M 33 x 2 of a bolt means
(a) metric threads of 33 nos in 2 cm.
(b) metric threads with cross-section of 33 mm
(c) metric threads of 33 mm outside diameter and 2
mm pitch
(d) bolt of 33 mm nominal diameter having 2 threads
per cm
(e) none of the above.
Ans: c
63. Machine screws are
(a) similar to small size tap bolts except that a
greater variety of shapes of heads are available
(b) slotted for a screw driver and generally used
with a nut
(c) used to prevent relative motion be-tween two
parts
(d) similar to stud
(e) none of the above.
Ans: b
64. Rivets are generally specified by
(a) thickness of plates to be riveted
(b) length of rivet
(c) diameter of head
(d) nominal diameter
(e) all of the above.
Ans: d
65. The edges of a boiler plate are bevelled to an
angle of
(a) 30°
(b) 45°
(c) 60°
(d) 80°
(e) 85°.
Ans: d
66. Which of the following is a permanent
fastening ?
(a) bolts
(b) keys
(c) cotters
(d) rivets
(e) screws.
Ans: d
67. In order to avoid tearing of the plate at edge, the
distance from the center line of the rivet hole to the
nearest edge of the plate in terms of dia. of rivet d
should be equal to
(a) d
(b) 1.25 d
(c) 1.5 d
(d) 1.75 d
(e) 2 d.
Ans: c
68. If the tearing efficiency of a riveted joint is 75%,
then the ratio of diameter of rivet to the pitch is
equal to
(a) 0.2
(b) 0.25
(c) 0.50
(d) 0.6
(e) 0.75.
Ans: b
69. Transverse fillet welded joints are designed for
(a) tensile strength
(b) compressive strength
(c) shear strength
(d) bending strength
(e) torsional strength.
Ans: a
70. Jam nut is a locking device in which
(a) one smaller nut is tightened over main nut and
main nut tightened against smaller one by
loosening, creating friction jamming
(b) a slot is cut partly in middle of nut and then slot
reduced by tightening a screw
(c) a hard fiber or nylon cotter is recessed in the
nut and becomes threaded as the nut is screwed on
the bolt causing a tight grip
(d) through slots are made at top and a cotter-pin is
passed through these and a hole in the bolt, and
cotter spitted and bent in reverse direction at other
end
(e) none of the above.
Ans: a
71. The pitch of threads on a Jock nut in
comparison to pitch of nut is
(a) same
(b) coarser
(c) finer
(d) very coarse
(e) very fine.
Ans: a
72.Buttress threads are usually found on
(a) screw cutting lathes
(b) feed mechanisms
(c) spindles of bench vices
(d) screw jack
(e) railway carriage couplings.
Ans: e
73. In order to obtain bolt of uniform strength
(a) increase shank diameter
(b) increase its length
(c) drill an axial hole through head up to threaded
portion so that shank area is equal to root area of
thread
(d) tighten die bolt properly
(e) all of the above.
Ans: c
74. A key capable of tilting in a recess milled out in
a shaft is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: a
75. A key made from a cylindrical disc having
segmental cross-section, is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: a
76. A tapered key which fits in a keyway in the hub
and is flat on the shaft, is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: c
77. Fibrous fracture occurs in
(a) ductile material
(b) brittle material
(c) elastic material
(d) hard material
(e) all of the above.
Ans: a
78. Turn buckle has
(a) right hand threads on bout ends
(b) left hand threads on both ends
(c) left hand threads on one end and right hand
threads on other end
(d) no threads
(e) threads in middle portion.
Ans: c
79. Eye bolts are used for
(a) foundation purposes
(b) locking devices *
(c) absorbing shock and vibrations
(d) transmission of power
(e) lifting and transportation of machines and
cubicles.
Ans: e
80. Elastic nut is a locking device in which
(a) one small nut is tightened over main nut and
main nut tightened against smaller one by
loosening, creating friction jamming
(b) a slot is cut partly in middle of nut and then slot
reduced by tightening a screw
(c) hard fiber or nylon cotter is recessed in the nut
and becomes threaded as the nut is stewed on the
bolt causing a tight grip
(d) through slots are made at top and a cotter-pin is
passed through these and a hole in the bolt, and
cotter pin splitted and bent in reverse direction at
other end
(e) none of the above,
Ans: c
81. If d is the normal diameter of a bolt in mm, then
the initial tension in kg in a bolt used for making a
fluid tight joint as for steam engine cover joint is
calculated by the relation
(a) 102 d
(b) 124 d
(c) 138 d
(d) 151 d
(e) 168 d.
Ans: e
82. If threads on a bolt are left hand, threads on nut
will be
(a) right hand with same pitch
(b) left hand with same pitch
(c) could be left or right hand
(d) right hand with fine pitch
(e) left hand with fine pitch.
Ans: b
83. Taper usually provided on cotter is
(a) 1 in 5
(b) 1 in 10
(c) 1 in 24
(d) 1 in 40
(e) 1 in 50.
Ans: c
84. Applications in which stresses are encountered
in one direction only uses following type of threads
(a) metric
(b) buttress
(c) acme
(d) square
(e) BSW.
Ans: b
85. The draw of cotter need not exceed
(a) 3 mm
(b) 5 mm
(c) 10 mm
(d) 20 mm
(e) 25 mm.
Ans: a
86. A bench vice has following type of threads
(a) metric
(b) square
(c) buttress
(d) acme
(e) BSW.
Ans: d
87. The valve rod in a steam engine is connected to
an eccentric rod by
(a) cotter joint
(b) bolted joint
(c) kunckle joint
(d) universal coupling
(e) gib and cotter joint.
Ans: c
88. Split nut is a locking device in which
(a) one smaller nut is tightened over main nut and
main nut tightened against smaller one by
loosening, creating friction jamming
(b) a slot is cut partly in middle of nut and then slot
reduced by tightening screw
(c) a hard fiber or nylon cotter is recessed in the
nut and becomes threaded as the nut is screwed on
the bolt causing a tight grip
(d) through slots are made at top and a cotter-pin is
passed through these and a hole in the bolt, and
cotter pin splitted and bent in reverse direction at
the other end
(e) none of the above.
Ans: b
89. Taper on the cotter and slot is provided
(a) on both the sides
(b) on one side only
(c) on none of the sides
(d) may be provided anywhere
(e) none of the above.
Ans: b
90. The function of cutting oil when threading a pipe
is to
(a) provide cooling action
(b) lubricate the dies
(c) help remove chips
(d) all of the above
(e) none of the above.
Ans: d
91. Silver-based solder is used for
(a) flaring
(b) brazing
(c) soft soldering
(d) fusion welding
(e) none of the above.'
Ans: b
92. For tight leakage joints, following type of thread
is best suited
(a) metric
(b) buttress
(c) square
(d) acme
(e) NPT (national pipe threads).
Ans: e
93. In order to permit the thermal expansion/
contraction of tubing, it should be
(a) crimped
(b) honed
(c) flared
(d) bent
(e) none of the above.
Ans: d
94. A tube has the following advantage over pipe
(a) lighter and easier to handle
(b) greater shock absorption
(c) smoother inside walls
(d) all of the above
(e) none of the above.
Ans: d
95. The strap end of a connecting rod of steam
engine is joined by
(a) gib of cotter joint
(b) sleeve and cotter joint
(c) spigot socket cotter joint
(d) knuckle joint
(e) universal coupling.
Ans: a
96. A backing ring is used inside the pipe joint when
making a
(a) butt weld
(b) fillet weld
(c) sleeve weld
(d) socket weld
(e) tube weld.
Ans: a
97. The shear plane in case of bolts should
(a) be across threaded portion of shank
(b) be parallel to axis of bolt
(c) be normal to threaded portion of shank
(d) never be across the threaded portion
(e) none of the above.
Ans: d
97. Castle nut is a locking device in which
(a) one smaller nut is tightened over main nut and
main nut tightened against smaller one by
loosening, creating friction jamming
(b) a slot is cut partly is middle of nut and then slot
reduced by tightening a screw
(c) a hard fiber or nylon cotter is recessed in the
nut and becomes threaded as the nut is screwed on
the bolt causing a tight grip
(d) through slots are made at top and a cotter pin is
passed through these and a hole in the bolt, and
cotter pin spitted and bent in reverse direction at
other end
(e) none of the above.
Ans: d
98. When a nut is tightened by plaping a washer
below it, the bolt will be subjected to following type
of loads
(a) compression
(b) tension
(c) shear
(d) combined loads
(e) all of the above.
Ans: b
99. Gear box is used
(a) to produce torque
(b) for speed reduction
(c) to obtain variable speeds
(d) to increase efficiency of system
(e) to damp out vibrations.
Ans: c
100. The edges of the plates for cylindrical vessels
are usually bevelled to an angle of 80° for
(a) reducing stress concentration
(b) ease of manufacture
(c) safety
(d) fullering and caulking
(e) all of the above.
Ans: d
101. The piston rod of a steam engine is usually
connected to the crosshead by means of
(a) bolted joint
(b) kunckle joint
(c) cotter joint
(d) universal joint
(e) universal coupling.
Ans: c
102. Which of the following pipe joints would be
suitable for pipes carrying steam
(a) flanged
(b) threaded
(c) bell and spigot
(d) expansion
(e) compression.
Ans: d
103. Spring index is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) indication of quality of spring
(e) nothing.
Ans: a
104. The shearing stresses in the inner face as
compared to outer face of the wire in a heavy close
coiled spring is
(a) larger
(b) smaller
(c) equal
(d) larger/smaller depending on diameter of spring
coil
(e) unpredictable.
Ans: a
105. Form coefficient of spring is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) concerned With strength of wire of spring
(e) nothing
Ans: c
106. Spring stiffness is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) its ability to absorb shocks
(e) none of the above.
Ans: b
107. When two springs are in series (having
stiffness K), the equivalent stiffness will be
(a) K
(b) K/2
(c) 2K
(d) KIA
(e) UK.
Ans: b
108. When a close coiled helical spring is
compressed, its wire is subjected to
(a) tension
(b) shear
(c) compression
(d) all of the above
(e) none of the above.
Ans: a
109. If a spring is cut down into two springs, the
stiffness of cut springs will be
(a) half
(b) same
(c) double
(d) unpredictable
(e) none of the above.
Ans: c
110. Belt slip may occur due to
(a) heavy load
(b) loose belt
(c) driving pulley too small
(d) all of the above
(e) none of the above.
Ans: d
111. Aircraft body is usually fabricated by
(a) welding
(b) precasting
(c) rivetting
(d) casting
(e) unconventional methods.
Ans: c
112. If two springs are in parallel then their overall
stiffness will be
(a) half
(b) same
(c) double
(d) unpredictable
(e) none of the above.
Ans: c
113. In hydrodynamic bearings
(a) the oil film pressure is generated only by the
rotation of the journal
(b) the oil film is maintained by supplying oil under
pressure
(c) do not require external supply of lubricant
(d) grease is used for lubrication
(e) none of the above.
Ans: a
114. Antifriction bearings are
(a) sleeve bearings
(b) hydrodynamic bearings
(c) thin lubricated bearings
(d) ball and roller bearings
(e) none of the above.
Ans: e
115. If p = bearing pressure on projected bearing
area, z = absolute viscosity of lubricant, and N =
speed of journal, then the bearing characteristic
number is given by
(a) ZN/p
(b) p/ZN
(c) Z/pN
(d) N/Zp
(e) Zp/N.
Ans: a
116. The usual clearance provided in hydrodynamic
bearing per mm of diameter of shaft is
(a) 0.01 micron
(b) 0.1 micron
(c) 1 micron
(d) 10 microns
(e) 25 microns.
Ans: c
117. In hydrostatic bearings
(a) the Oil film pressure is generated only by the
rotation of the journal
(b) the oil film is maintained by supplying oil under
pressure
(c) do not require external supply of lubricant
(d) grease is used for lubrication
(e) none of the above.
Ans: b
118. Oil in journal bearing should be applied at the
point where load is
(a) nil or lightest
(b) maximum
(c) average
(d) any one of the above
(e) unpredictable.
Ans: a
119. The rated life of a bearing varies
(a) directly as load
(b) inversely as square of load
(c) inversely as cube of load
(d) inversely as fourth power of load
(e) none of the above.
Ans: c
120. In oilness bearings
(a) the oil film pressure is generated only by the
rotation of the journal
(b) the oil film is maintained by supplying oil under
pressure
(c) do not require external supply of lubricant
(d) grease required to be applied after some
intervals
(e) none of the above.
Ans: c
121. In V-belt drive, belt touches
(a) at bottom
(b) at sides only
(c) both at bottom and sides
(d) could touch anywhere
(e) none of the above.
Ans: b
122. Three different weights fall from a certain
height under vacuum. They will take
(a) same time to reach earth
(b) times proportional to weight to reach earth
(c) times inversely proportional to weight to reach
earth
(d) unpredictable
(e) none of the above.
Ans: a
123. In cross or regular lay ropes
(a) direction of twist of wires in strands is opposite
to the direction of twist of strands
(b) direction of twist of wires and strands are same
(c) wires in two adjacent strands are twisted in
opposite direction
(d) wires are not twisted
(e) none of the above.
Ans: a
124. In standard taper roller bearings, the angle of
taper of outer raceway is
(a) 5°
(b) 8°
(c) 15°
(d) 25°
(e) 40°.
Ans: d
125. In composite or reverse laid ropes
(a) direction of twist of wires in strands is opposite
to the direction of twist of strands
(b) direction of twist of wires and strands are same
(c) wires in two adjacent strands are twisted in
opposite direction
(d) wires are not twisted
(e) none of the above.
Ans: c
126. Whether any core is required in wire ropes
(a) yes
(b) no
(c) sometimes
(d) rarely
(e) very often.
Ans: a
127. If shearing stress in nut is half the tensile
stress in a bolt, then nut length should be equal to
(a) diameter of bolt
(b) 0.75 x diameter of bolt
(c) 1.25 x diameter of bolt
(d) 1.5 x diameter of bolt
(e) 0.5 x diameter of bolt.
Ans: a
128. Basic shaft is one
(a) whose upper deviation is zero
(b) whose lower deviation is zero
(c) whose lower as well as upper deviations are
zero
(d) does not exist
(e) none of the above.
Ans: a
129. Basic hole is one
(a) whose upper deviation is zero
(b) whose lower deviation is zero
(c) whose lower as well as upper deviations are
zero
(d) does not exist
(e) none of the above.
Ans: b
130. I.S. specifies following total number of grades
of tolerances
(a) 18
(b) 16
(c) 20
(d) 22
(e) 14.
Ans: a
131. For standard coarse threads of nut, the threads
will be as strong in failure by shear as the bolt in
tension, if the height of nut (h) is approximately
(a) 0.4 times
(b) 0.6 times
(c) 0.7 times
(d) 0.8 times
(e) 0.9 times the normal diameter of bolt.
Ans: a
132. Allen bolts are
(a) self locking bolts
(b) designed for shock load
(c) used in aircraft application
(d) provided with hexagonal depression in head
(e) uniform strength bolts.
Ans: d
133. The resultant axial load on a bolt depends on
(a) initial tension
(b) external load applied
(c) relative elastic yielding (springness) of the bolt
and the connected member
(d) (a) and (b) above
(e) (a), (b) and (c) above.
Ans: e
134. The connecting rod bolts are tightened up so
that tightening stress
(a) is just sufficient to hold parts together
(b) approaches yield point
(c) is 50% of yield point
(d) is about yield point divided by safety factor
(e) none of the above.
Ans: b
135. The connecting rod bolts are tightened up with
initial tension greater than the external load so that
(a) joint may not open up
(b) bolts are weakest elements
(c) the resultant load on the bolt would not be
affected by the external cyclic load
(d) bolts will not loosen during service
(e) none of the above.
Ans: c
136. If an application calls for stresses on screw
threads in one direction only, then the following type
of thread would be best suited
(a) square
(b) acme
(c) buttress
(d) BSW
(e) metric.
Ans: c
137. When a bolt is subjected to shock loading, the
resilience of the bolt should be considered in order
to prevent breakage at
(a) shank
(b) head
(c) in the middle
(d) at the thread
(e) anywhere in the bolt.
Ans: d
138. The shock absorbing capacity of a bolt can be
increased by
(a) tightening it properly
(b) increasing shank diameter
(c) grinding the shank
(d) using washer
(e) making shank diameter equal to core diameter
of thread.
Ans: e