Mock paper 1 for mechanical
1) 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 & temperature are kept constant.
2) 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
3) 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 & not on the state
e) remains constant
4) The same volume of all gases would represent their
a) densities
b) specific weights
c) molecular weights
d) gas characteristic constants
e) specific gravities
5) properties of substances like pressure, temperature & density, in thermodynamic coordinates are
a) path functions
b) point functions
c) cyclic functions
d) real functions
e) thermodynamic functions
6) 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
7) first law of thermodynamics
a) enables to determine change in internal energy to 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 relation between heat, work & internal energy
e) all of the above
8) entropy is called the property of the system because
a) its derivative is zero for any process
b) it has same value at any two equilibrium state
c) it has a single value at each equilibrium state
d) it has a constant value at each equilibrium state
e) it depends upon the path followed by the system
9) if a steam sample is nearly in dry condition, then its dryness fraction can be accurately determined by
a) throttling calorimeter
b) separating calorimeter
c) combined separating & throttling calorimeter
d) bucket calorimeter
e) none of the above
10) on Mollier chart, flow through turbine is represented by
a) horizontal straight line
b) vertical straight line
c) straight inclined line
d) curved line
e) none of the above
11) In a throttling process
a) heat transfer takes place
b) work is done by the expanding steam
c) internal energy of steam changes
d) all of the above
e) none of the above
12) pick up the wrong statement about critical condition of steam
a) latent heat is zero
b) liquid directly becomes steam
c) specific volume of steam & liquid is same
d) this is the maximum pressure limit
e) all properties of liquid & steam are same
13) during polytropic process
a) heat transfer takes place across cylinder walls
b) work is done
c) steam may be wet, dry or superheated after expansion
d) all of the above
e) none of the above
14) the fusible plug in small boilers is located
a) in the drum
b) in the fire tubes
c) above steam dome
d) over the combustion chamber
e) at the inlet of chimney
15) steam in water tube boiler as compared to fire tube boiler
a) can be raised rapidly
b) is raised at slower rate
c) is raised at same rate
d) could be raised at fast/slow rate depending on design
e) none of the above
16) the overall efficiency of thermal power plant is
a) boiler efficiency, turbine efficiency, generator efficiency
b) all the three above plus gas cycle efficiency
c) carnot cycle efficiency
d) regenerative cycle efficiency
e) rankine cycle efficiency
17) size of boiler tubes is specified by
a) mean diameter & thickness
b) inside diameter & thickness
c) outside diameter & thickness
d) outside diameter & inside diameter
e) outside diameter alone
18) The temperature of flue gases at air heater outlet should be
a) 100o C
b) above dew-point temperature of flue gases
c) below dew-point temperature of flue gases
d) less than wet bulb temperature of flue gases
e) above wet bulb temperature of flue gases
19) tertiary air is the air used to
a) provide air around burners for obtaining optimum combustion
b) transport & dry the coal
c) cool the scanners
d) supply air for ignitors
e) convert CO (formed in lower zone of furnace) into CO2 at higher zone
20) boiler parameters are expressed by
a) tones/hr. of steam
b) pressure of steam produced
c) temperature of steam in oC
d) all of the above
e) none of the above
21) the condition of steam in boiler drum is always
a) dry
b) wet
c) saturated
d) supersaturated
e) superheated
22) film boiling occurs at
a) very low pressure
b) atmospheric pressures
c) medium pressures
d) very high pressures
e) none of the above
23) a thermal power plant designed to operate in cold climate is operated in hot climate; it will develop
a) more power
b) less power
c) same power
d) more or less depending on the size
e) unpredictable
24) which statement is not true for steam turbine in comparison to steam engines
a) there is no boiler-water contamination from lubricating oil as in a steam engine
b) turbine delivers smooth uninterrupted power at high rotating speeds
c) turbines have less weight per horse-power &
power wearing parts compared to steam engines
d) heat energy of steam is better utilized in steam
engines than in turbines
e) all of the above
25) velocity compounding involves
a) expansion of steam in stages
b) recovery of kinetic energy of steam leaving first
set of blades in subsequent rows of blades
c) velocity & pressure equalization at different stages
d) increased velocity after each stage due to
expansion of steam
e) none of the above
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