Mechanical Engineering : Engineering Thermodynamics MCQs with Answers

1 .
According to kinetic theory of gases, the kinetic energy of translation of a molecule is proportional to
A)  T
B)  √T
C)  1/T
D)  1/√T

Correct Answer :   T

2 .
What is thermodynamics?
A)  study of the conversion of chemical energy to other forms of energy
B)  study of the conversion of mechanical energy to other forms of energy
C)  study of the relationship between heat and other forms of energy
D)  study of the relationship between mechanical energy to other forms of energy

Correct Answer :   study of the relationship between heat and other forms of energy

Explanation : The branch of physical science is concerned with the relationship between heat, and other forms of energy like mechanical, electrical, chemical energy, etc.

3 .
Which of the following is a branch of thermodynamics?
A)  Chemical thermodynamics
B)  Classical thermodynamics
C)  Equilibrium thermodynamics
D)  All of the above

Correct Answer :   All of the above

Explanation : The branches of thermodynamics include :

1) Equilibrium thermodynamics
2) Classical thermodynamics
3) Chemical thermodynamics
4) Statistical mechanics or Statistical thermodynamics

4 .
The amount of heat given out by the complete combustion of 1 kg of fuel is known as calorific value of solid or liquid fuel.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

5 .
The sum of internal energy (U) and the product of pressure and volume (p.v) is known as
A)  entropy
B)  enthalpy
C)  workdone
D)  None of the above

Correct Answer :   enthalpy

6 .
The behaviour of a perfect gas, undergoing any change in the variables which control physical properties, is governed by
A)  Boyle's law
B)  Charles' law
C)  Gay-Lussac law
D)  All of the above

Correct Answer :   All of the above

7 .
The universal gas constant of a gas is the product of molecular mass of the gas and the gas constant.
A)  Correct
B)  Incorrect
C)  Can Not Say
D)  None of the above

Correct Answer :   Correct

8 .
One kg of carbon requires 4/3 kg of oxygen and produces __________ kg of carbon monoxide gas.
A)  11/3
B)  11/7
C)  7/3
D)  8/3

Correct Answer :   7/3

9 .
Which of the following is a thermodynamics law?
A)  Boyle’s Law of thermodynamics
B)  Zeroth law of thermodynamics
C)  Faraday’s Law of thermodynamics
D)  Ideal Gas Law of thermodynamics

Correct Answer :   Ideal Gas Law of thermodynamics

Explanation : Thermodynamics is primarily based on a set of four rules that are universally applicable when applied to systems that fall within their respective limitations. They are as follows:

* Zeroth law of thermodynamics
* First law of thermodynamics
* Second law of thermodynamics
* Third law of thermodynamics

10 .
The value of 1 mm of Hg is equal to
A)  1.333 N/m²
B)  13.33 N/m²
C)  133.3 N/m²
D)  1333 N/m²

Correct Answer :   133.3 N/m²

11 .
The conditions of temperature and pressure at 0°C (273K) and 760 mm of Hg pressure are termed as __________ temperature and pressure.
A)  normal
B)  standard
C)  Can Not Say
D)  None of the above

Correct Answer :   standard

Explanation : Standard temperature and pressure (STP) and Normal temperature and pressure (NTP) are two sets of reference conditions that are commonly used in science and engineering.

The main difference between STP and NTP is the temperature and pressure values that they represent.

STP is defined as a temperature of 0 degrees Celsius (273.15 K) and a pressure of 1 atmosphere (101.325 kPa or 760 mmHg).

STP is often used as a reference for measuring gas volumes and is commonly used in fields such as chemistry and physics.

NTP, on the other hand, is defined as a temperature of 20 degrees Celsius (293.15 K) and a pressure of 1 atmosphere (101.325 kPa or 760 mmHg). NTP is often used as a reference for measuring gas flow rates and is commonly used in fields such as engineering and environmental science.

It is important to note that STP and NTP are not interchangeable and their specific values should be used according to the context and application of the measurement being made.

12 .
The heat absorbed or rejected by the working substance is given by (where ds = Increase or decrease of entropy, T = Absolute temperature, and dQ = Heat absorbed or rejected)
A)  δQ = T.ds
A)  
B)  δQ = T/ds
B)  
C)  dQ = ds/T
C)  
D)  None of the above
D)  

Correct Answer :   δQ = T.ds

13 .
The value of cp/cv for air is
A)  1
A)  
B)  1.4
B)  
C)  1.8
C)  
D)  2.9
D)  

Correct Answer :   1.4

14 .
The area under the temperature-entropy curve (i. e. T - s curve) of any thermodynamic process represents the workdone during the process.
A)  Agree
B)  Disagree
C)  Can Not Say
D)  None of the above

Correct Answer :   Disagree

15 .
An open system is one in which
A)  heat and work crosses the boundary of the system, but the mass of the working substance does not crosses the boundary of the system
B)  mass of the working substance crosses the boundary of the system but the heat and work does not crosses the boundary of the system
C)  both the heat and work as well as mass of the working substance crosses the boundary of the system
D)  neither the heat and work nor the mass of the working substance crosses the boundary of the system

Correct Answer :   both the heat and work as well as mass of the working substance crosses the boundary of the system

16 .
In closed cycle gas turbine, the air is compressed
A)  isentropically
B)  isothermally
C)  polytropically
D)  None of the above

Correct Answer :   isentropically

17 .
When the gas is heated at constant volume, the heat supplied
A)  increases the internal energy of the gas and increases the temperature of the gas
B)  does some external work during expansion
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   increases the internal energy of the gas and increases the temperature of the gas

18 .
Heat does not spontaneously flow from a colder body to a hotter one. Which of the following thermodynamics law states this?
A)  Zeroth law of thermodynamics
B)  First law of thermodynamics
C)  Second law of thermodynamics
D)  Third law of thermodynamics

Correct Answer :   Second law of thermodynamics

Explanation : The concept of entropy as a physical attribute of a thermodynamic system is established by the second law of thermodynamics. Despite following the necessity of energy conservation as specified in the first law of thermodynamics, entropy predicts the direction of spontaneous processes and determines whether they are irreversible or impossible.

19 .
Which of the following is an application of thermodynamics?
A)  Refrigerators
B)  Power plants
C)  Gas compressors
D)  All of the above

Correct Answer :   Power plants

Explanation : The second law of thermodynamics applies to all refrigerators, deep freezers, industrial refrigeration systems, all forms of air-conditioning systems, heat pumps, and so on. Thermodynamic cycles govern the operation of all forms of air and gas compressors, blowers, and fans. The study of the feasibility of employing various forms of renewable energy sources for household and commercial purposes is an important topic area of thermodynamics.

20 .
Which of the following is a type of thermodynamic system?
A)  Open system
B)  Closed system
C)  Thermally isolated system
D)  All of the above

Correct Answer :   All of the above

Explanation : The types of thermodynamic systems are :

i) Open system
ii) Closed system
iii) Thermally isolated system
iv) Mechanically isolated system
v) Isolated system

21 .
One reversible heat engine operates between 1600 K and T₂ K and another reversible heat engine operates between T₂ K and 400 K. If both the engines have the same heat input and output, then temperature T₂ is equal to
A)  800K
A)  
B)  1000K
B)  
C)  1200K
C)  
D)  1400K
D)  

Correct Answer :   800K

22 .
According to Kelvin-Planck's statement of second law of thermodynamics,
A)  it is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
B)  it is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
C)  it is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body
D)  None of the above

Correct Answer :   it is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

23 .
According to Gay-Lussac law, the absolute pressure of a given mass of a perfect gas varies __________ as its absolute temperature, when the volume remains constant.
A)  directly
B)  indirectly
C)  Can Not Say
D)  None of the above

Correct Answer :   directly

24 .
Which of the following gas has a minimum molecular mass?
A)  Oxygen
B)  Methane
C)  Hydrogen
D)  Nitrogen

Correct Answer :   Hydrogen

25 .
A process, in which the temperature of the working substance remains constant during its expansion or compression, is called
A)  adiabatic process
B)  isothermal process
C)  polytropic process
D)  hyperbolic process

Correct Answer :   isothermal process

26 .
According to Avogadro's law
A)  the sum of partial pressure of the mixture of two gases is sum of the two
B)  the product of the gas constant and the molecular mass of an ideal gas is constant
C)  equal volumes of all gases, at the same temperature and pressure, contain equal number of molecules
D)  All of the above

Correct Answer :   equal volumes of all gases, at the same temperature and pressure, contain equal number of molecules

27 .
For the same maximum pressure and temperature,
A)  Otto cycle is more efficient than Diesel cycle
B)  Dual cycle is more efficient than Otto and Diesel cycles
C)  Dual cycle is less efficient than Otto and Diesel cycles
D)  Diesel cycle is more efficient than Otto cycle

Correct Answer :   Diesel cycle is more efficient than Otto cycle

28 .
The unit of energy is S. I. units is
A)  Joule (J)
B)  Watt(W)
C)  Joule metre (Jm)
D)  Joule/metre (J/m)

Correct Answer :   Joule (J)

29 .
Select the correct statement as per Charles' law
A)  p/T = constant, if v is kept constant
B)  v/T = constant, if p is kept constant
C)  p.v = constant, if T is kept constant
D)  T/p = constant, if v is kept constant

Correct Answer :   v/T = constant, if p is kept constant

30 .
In a steady flow process, the rate of
A)  heat transfer is constant
B)  work transfer is constant
C)  mass flow at inlet and outlet is same
D)  All of the above

Correct Answer :   All of the above

31 .
The entropy of the universe is continually on the increase.
A)  Correct
B)  Incorrect
C)  Can Not Say
D)  None of the above

Correct Answer :   Correct

32 .
A cycle consisting of two constant pressure and two isothermal processes is known as Ericsson cycle.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

33 .
A process of heating crude oil to a high temperature under a very high pressure to increase the yield of lighter distillates, is known as
A)  carbonisation
B)  full distillation
C)  cracking
D)  fractional distillation

Correct Answer :   cracking

34 .
If in the equation pvn = C, the value of n = 1, then the process is called isothermal process.
A)  True
A)  
B)  False
B)  
C)  Can Not Say
C)  
D)  None of the above
D)  

Correct Answer :   True

35 .
Which of the following process can be made reversible with the help of a regenerator?
A)  Constant pvn process
B)  Constant volume process
C)  Constant pressure process
D)  All of the above

Correct Answer :   All of the above

36 .
The specific volume of a system is an __________ property.
A)  extensive
B)  intensive
C)  Can Not Say
D)  None of the above

Correct Answer :   intensive

37 .
The atomic mass of sulphur is
A)  12
B)  14
C)  16
D)  32

Correct Answer :   32

38 .
A cycle consisting of two isothermal and two isentropic processes, is known as
A)  Carnot cycle
B)  Joule cycle
C)  Stirling cycle
D)  Ericsson cycle

Correct Answer :   Carnot cycle

39 .
A path 1-2-3 is given. A system absorbs 100 kJ as heat and does 60 kJ of work while along the path 1-4-3, it does 20 kJ of work. The heat absorbed during the cycle 1-4-3 is
Thermodynamics
A)  -40 kJ
A)  
B)  +60 kJ
B)  
C)  -80 kJ
C)  
D)  -140 kJ
D)  

Correct Answer :   +60 kJ

40 .
In an ideal gas turbine plant, it is assumed that the compression and expansion processes are
A)  isothermal
B)  polytropic
C)  isentropic
D)  None of the above

Correct Answer :   isentropic

41 .
When wood is heated with a limited supply of air to a temperature not less than 280°C, the resulting fuel is
A)  coke
B)  bituminous coal
C)  wood charcoal
D)  briquetted coal

Correct Answer :   wood charcoal

42 .
The amount of heat required to raise the temperature of 1 kg of water through one Kelvin is called
A)  specific heat at constant volume
B)  kilo-Joule
C)  specific heat at constant pressure
D)  None of the above

Correct Answer :   kilo-Joule

43 .
When gas is heated at constant pressure, the heat supplied is utilised in
A)  doing some external work
B)  increasing the internal energy of gas
C)  increasing the internal energy of gas and also for doing some external work
D)  None of the above

Correct Answer :   increasing the internal energy of gas and also for doing some external work

44 .
Carnot cycle consists of
A)  two isothermal and two isentropic processes
B)  two constant volume and two isentropic processes
C)  two constant pressure and two isentropic processes
D)  one constant volume, one constant pressure and two isentropic processes

Correct Answer :   two isothermal and two isentropic processes

45 .
When a gas is heated at constant volume
A)  its temperature will increase
B)  its pressure will increase
C)  neither temperature nor pressure will increase
D)  both temperature and pressure will increase

Correct Answer :   both temperature and pressure will increase

46 .
The ratio of molar specific heats for monoatomic gas is
A)  1
B)  1.4
C)  1.67
D)  1.92

Correct Answer :   1.67

47 .
The numerical value of the thermal capacity and the water equivalent of the substance are the same.
A)  Agree
B)  Disagree
C)  Can Not Say
D)  None of the above

Correct Answer :   Agree

48 .
The state of a substance whose evaporation from its liquid state is partial, is known as steam.
A)  Agree
B)  Disagree
C)  Can Not Say
D)  None of the above

Correct Answer :   Disagree

49 .
The general law of expansion or compression is pvn = C, The process is said to be hyperbolic, if n is equal to
A)  
B)  1
B)  
C)  γ
C)  
D)  ∝
D)  

Correct Answer :   1

50 .
Which of the following occurs without a change in the internal energy?
A)  Isochoric process
B)  Isenthalpic process
C)  Isenthalpic process
D)  Steady-state process

Correct Answer :   Steady-state process

Explanation : The following are some of the most commonly studied thermodynamic processes :

i) Heat does not lose or acquire energy in an adiabatic process.
ii) At a constant enthalpy, the isenthalpic process occurs.
iii) The isobaric process happens when the pressure remains constant.
iv) The isochoric process (also known as isometric/isovolumetric) happens at a constant volume.
v) At a constant temperature, an isothermal process occurs.
vi) Internal energy does not change in a steady-state operation.
vii) Isentropic process: adiabatic reversible process with constant entropy.

51 .
Which of the following thermodynamic law gives the concept of enthalpy?
A)  First law of thermodynamics
B)  Second law of thermodynamics
C)  Third law of thermodynamics
D)  Fourth law of thermodynamics

Correct Answer :   Third law of thermodynamics

Explanation : The first law of thermodynamics connects a system’s many kinds of kinetic and potential energy to the work it can do and the heat it can transfer. This law, which also includes an extra state variable, enthalpy, is occasionally used to define internal energy.

52 .
Stirling and Ericsson cycles are
A)  reversible cycles
B)  irreversible cycles
C)  quasi-static cycles
D)  semi-reversible cycles

Correct Answer :   reversible cycles

53 .
When cut-off ratio is __________ the efficiency of Diesel cycle approaches to Otto cycle efficiency.
A)  zero
B)  1
C)  1/5
D)  4/5

Correct Answer :   zero

54 .
An isothermal process is governed by
A)  Charles' law
B)  Boyle's law
C)  Gay-Lussac law
D)  Avogadro's law

Correct Answer :   Boyle's law

55 .
A series of operations, which takes place in a certain order and restore the initial conditions at the end, is known as
A)  reversible cycle
B)  irreversible cycle
C)  thermodynamic cycle
D)  None of the above

Correct Answer :   thermodynamic cycle

56 .
One kg of carbon requires 8/3 kg of oxygen for its complete combustion and produces 11/3 kg of carbon dioxide gas.
A)  Agree
B)  Disagree
C)  Can Not Say
D)  None of the above

Correct Answer :   Agree

57 .
One m³ of methane (CH₄) requires 2m³ of oxygen and produces 1m³ of carbon dioxide and 2m³ of water or steam.
A)  Correct
A)  
B)  Incorrect
B)  
C)  Can Not Say
C)  
D)  None of the above
D)  

Correct Answer :   Correct

58 .
The standard value of atmospheric pressure taken at sea level is
A)  1.013 bar
B)  760 mm of Hg
C)  1013 x 10² N/m²
D)  All of the above

Correct Answer :   All of the above

59 .
One kg of ethylene (C₂H₄) requires 2 kg of oxygen and produces 22/7 kg of carbon dioxide and ___kg of water or steam.
A)  7/4
A)  
B)  9/7
B)  
C)  11/4
C)  
D)  11/7
D)  

Correct Answer :   9/7

60 .
The smallest quantity of a substance, which can exist by itself in a chemically recognizable form is known as
A)  atom
B)  molecule
C)  element
D)  compound

Correct Answer :   molecule

61 .
What is the value of the absolute thermodynamic temperature scale?
A)  0K
B)  1K
C)  3K
D)  4K

Correct Answer :   0K

Explanation : The temperature of an object on a scale with 0 as absolute zero is known as absolute temperature, also known as thermodynamic temperature. Kelvin and Rankine are absolute temperature scales.

62 .
Which of the following follows the Carnot theorem?
A)  Heat engines
B)  Gas compressors
C)  Gas turbine engines
D)  All of the above

Correct Answer :   All of the above

Explanation : Carnot’s theorem states that all heat engines between two heat reservoirs are less efficient than a Carnot heat engine operating between the same reservoirs.

63 .
If a piston/cylinder with a cross-sectional size of 0.01 m2 is resting on the stops, what should the water pressure be to lift the piston with an outside pressure of 100 kPa?
A)  168kPa
B)  198kPa
C)  218kPa
D)  318kPa

Correct Answer :   198kPa

Explanation : Pw = Po + mg/A = 100000 + (100*9.8/0.01) = 198kPa.

64 .
The total energy of a molecule is shared equally by the various degrees of freedom possessed by it. This law is known as
A)  law of degradation of energy
B)  law of conservation of energy
C)  law of equipartition of energy
D)  None of the above

Correct Answer :   law of equipartition of energy

65 .
The thermodynamic property of a system is said to be an intensive property whose value for the entire system __________ the sum of their value for the individual parts of the system.
A)  is equal to
B)  is not equal to
C)  Can Not Say
D)  None of the above

Correct Answer :   is not equal to

66 .
The efficiency of Joule cycle is
A)  greater than Carnot cycle
B)  equal to Carnot cycle
C)  less than Carnot cycle
D)  All of the above

Correct Answer :   less than Carnot cycle

67 .
The fuel mostly used in steam boilers is
A)  peat
B)  brown coal
C)  coking bituminous coal
D)  non-coking bituminous coal

Correct Answer :   non-coking bituminous coal

68 .
The hyperbolic pocess is governed by
A)  Boyle's law
B)  Charles' law
C)  Gay-Lussac law
D)  Avogadro's law

Correct Answer :   Boyle's law

69 .
During which of the following process does heat rejection takes place in Carnot cycle?
A)  Isothermal expansion
B)  Isentropic expansion
C)  Isentropic compression
D)  Isothermal compression

Correct Answer :   Isothermal compression

70 .
The entropy of water at 0°C is assumed to be
A)  1
B)  0
C)  -1
D)  10

Correct Answer :   0

71 .
The greater the pressure difference in throttling, the lesser is the irreversibility.
A)  Yes
B)  No
C)  Can Not Say
D)  None of the above

Correct Answer :   Yes

72 .
Which is the incorrect statement about Carnot cycle?
A)  It is used as the alternate standard of comparison of all heat engines.
B)  It provides concept of maximising work output between the two temperature limits.
C)  All the heat engines are based on Carnot cycle.
D)  All of the above

Correct Answer :   All the heat engines are based on Carnot cycle.

73 .
A process, in which the gas is heated or expanded in such a way that the product of its pressure and volume remains constant, is called
A)  adiabatic process
B)  polytropic process
C)  hyperbolic process
D)  isothermal process

Correct Answer :   hyperbolic process

74 .
Diesel cycle consists of __________ processes.
A)  two constant volume and two isothermal
B)  two constant volume and two isentropic
C)  two constant pressure and two isentropic
D)  one constant pressure, one constant volume and two isentropic

Correct Answer :   one constant pressure, one constant volume and two isentropic

75 .
Which of the following statement is correct according to Clausis statement of second law off thermodynamics?
A)  It is possible to transfer heat from a body at a lower temperature to a body at a higher temperature.
B)  It is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature, without the aid of an external source.
C)  It is possible to transfer heat from a body at a lower temperature to a body at a higher temperature by using refrigeration cycle.
D)  None of the above

Correct Answer :   It is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature, without the aid of an external source.

76 .
If in the equation pvn = C, the value of n = ∝ , then the process is called
A)  constant volume process
A)  
B)  adiabatic process
B)  
C)  isothermal process
C)  
D)  constant pressure process
D)  

Correct Answer :   constant volume process

77 .
The behaviour of super-heated vapour is similar to that of
A)  air
B)  steam
C)  ordinary gas
D)  perfect gas

Correct Answer :   perfect gas

78 .
Which of the following is a reversible non-flow process?
A)  Isobaric process
B)  Isochoric process
C)  Hyperbolic process
D)  All of the above

Correct Answer :   All of the above

79 .
A molecule consisting of one atom is known as
A)  monoatomic
B)  diatomic
C)  triatomic
D)  polyatomic

Correct Answer :   monoatomic

80 .
The amount of heat required to raise the temperature of __________ water through one degree is called kilojoule.
A)  1 g
B)  10 g
C)  100 g
D)  1000 g

Correct Answer :   1000 g

81 .
A definite area or a space where some thermodynamic process takes place is known as
A)  thermodynamic law
B)  thermodynamic system
C)  thermodynamic cycle
D)  thermodynamic process

Correct Answer :   thermodynamic system

82 .
The natural petroleum may be separated into
A)  petrol
B)  kerosene
C)  fuel oil
D)  lubricating oil

Correct Answer :   lubricating oil

83 .
A process, in which the working substance neither receives nor gives out heat to its surroundings during its expansion or compression, is called
A)  adiabatic process
B)  hyperbolic process
C)  isothermal process
D)  polytropic process

Correct Answer :   adiabatic process

84 .
The universal gas constant (or molar constant) of a gas is the product of
A)  atomic mass of the gas and the gas constant
B)  molecular mass of the gas and the specific heat at constant volume
C)  molecular mass of the gas and the gas constant
D)  molecular mass of the gas and the specific heat at constant pressure

Correct Answer :   molecular mass of the gas and the gas constant

85 .
The property of a working substance which increases or decreases as the heat is supplied or removed in a reversible manner, is known as
A)  enthalpy
B)  entropy
C)  internal energy
D)  external energy

Correct Answer :   entropy

86 .
It is __________ to make an engine working on a Carnot cycle.
A)  possible
B)  impossible
C)  Can Not Say
D)  None of the above

Correct Answer :   impossible

87 .
The heating of a gas at constant pressure is governed by
A)  Boyle's law
B)  Gay-Lussac law
C)  Avogadro's law
D)  Charles' law

Correct Answer :   Charles' law

88 .
Reversed Joule cycle is known as
A)  Bell-Coleman cycle
B)  Carnot cycle
C)  Rankine cycle
D)  Stirling cycle

Correct Answer :   Bell-Coleman cycle

89 .
Energy can neither be created nor destroyed, but it can be transformed from one form to another. This statement is known as
A)  Zeroth law of thermodynamics
B)  First law of thermodynamics
C)  Second law of thermodynamics
D)  Kinetic theory of gases

Correct Answer :   First law of thermodynamics

90 .
Which of the following is the extensive property of a thermodynamic system?
A)  Density
B)  Volume
C)  Pressure
D)  Temperature

Correct Answer :   Volume

91 .
One kilowatt is equal to
A)  1 N-m/s
B)  100 N-m
C)  1000 N-m/s
D)  1 x 10⁶ N-m/s

Correct Answer :   1000 N-m/s

92 .
Second law of thermodynamics defines
A)  entropy
B)  heat
C)  work
D)  internal energy

Correct Answer :   entropy

93 .
According to kinetic theory of gases, the velocity of molecules __________ with the increase in temperature.
A)  remains constant
B)  increases
C)  decreases
D)  None of the above

Correct Answer :   increases

94 .
Stirling cycle consists of
A)  two constant volume and two isentropic processes
B)  two constant pressure and two isothermal processes
C)  two constant volume and two isothermal processes
D)  one constant volume, one constant pressure and two isentropic processes

Correct Answer :   two constant volume and two isothermal processes

95 .
The hard coke is obtained when carbonisation of coal is carried out at
A)  300° to 500°C
B)  500° to 700°C
C)  700° to 900°C
D)  900° to 1100°C

Correct Answer :   900° to 1100°C

96 .
According to First law of thermodynamics,
A)  total energy of a system remains constant
B)  total internal energy of a system during a process remains constant
C)  workdone by a system is equal to the heat transferred by the system
D)  internal energy, enthalpy and entropy during a process remains constant

Correct Answer :   total energy of a system remains constant

97 .
According to Avogadro's law, the density of any two gases is __________ their molecular masses, if the gases are at the same temperature and pressure.
A)  equal to
B)  directly proportional to
C)  inversely proportional to
D)  None of the above

Correct Answer :   directly proportional to

98 .
The specific heat of water is
A)  1.817
B)  4.187
C)  2512
D)  None of the above

Correct Answer :   4.187

99 .
One kg of carbon monoxide requires __________ kg of oxygen to produce 11/7 kg of carbon dioxide gas.
A)  4/7
B)  9/7
C)  11/4
D)  All of the above

Correct Answer :   4/7

100 .
The absolute zero temperature is taken as
A)  237°F
B)  -237°F
C)  273°C
D)  -273°C

Correct Answer :   -273°C

101 .
In an isolated system, neither the heat and work nor the, mass of the working substance crosses the boundary of the system.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

102 .
The compression ratio is the ratio of
A)  swept volume to total volume
B)  total volume to swept volume
C)  total volume to clearance volume
D)  swept volume to clearance volume

Correct Answer :   total volume to clearance volume

103 .
One molecule of oxygen consists of ___ atoms of oxygen.
A)  2
B)  4
C)  8
D)  16

Correct Answer :   2

104 .
The efficiency of Ericsson cycle is __________ Carnot cycle.
A)  less than
B)  equal to
C)  greater than
D)  None of the above

Correct Answer :   equal to

105 .
For the same compression ratio, the efficiency of Diesel cycle is __________ Otto cycle.
A)  greater than
B)  less than
C)  equal to
D)  None of the above

Correct Answer :   less than

106 .
In open cycle gas turbine plants
A)  a condenser is used
B)  direct combustion system is used
C)  the indirect heat exchanger and cooler is avoided
D)  All of the above

Correct Answer :   All of the above

107 .
Mond gas is obtained by______.
A)  carbonisation of bituminous coal
B)  passing steam over incandescent coke
C)  passing air and a large amount of steam over waste coal at about 650°C
D)  partial combusion of coal, coke, anthracite coal or charcoal in a mixed air steam blast

Correct Answer :   passing air and a large amount of steam over waste coal at about 650°C

108 .
The natural solid fuel is
A)  wood
B)  coke
C)  anthracite coal
D)  pulverised coal

Correct Answer :   wood

109 .
The condition for the reversibility of a cycle is
A)  the working parts of the engine must be friction free
B)  all the processes, taking place in the cycle of operation, must be extremely slow
C)  the pressure and temperature of the working substance must not differ, appreciably, from those of the surroundings at any stage in the process
D)  All of the above

Correct Answer :   All of the above

110 .
Which of the following gas is mostly used in town for street and domestic lighting and heating?
A)  Mond gas
B)  Coal gas
C)  Producer gas
D)  Coke oven gas

Correct Answer :   Coal gas

111 .
The value of gas constant (R) in S. I. units is
A)  287 J/kgK
B)  28.7 J/kgK
C)  2.87 J/kgK
D)  0.287 J/kgK

Correct Answer :   287 J/kgK

112 .
The efficiency of Diesel cycle increases with
A)  constant cut-off
B)  decrease in cut-off
C)  increase in cut-off
D)  None of the above

Correct Answer :   decrease in cut-off

113 .
The value of specific heat at constant pressure (cp) is __________ that of at constant volume (cv).
A)  less than
A)  
B)  equal to
B)  
C)  more than
C)  
D)  None of the above
D)  

Correct Answer :   more than

114 .
When coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel, the process is known as __________ of fuel.
A)  atomisation
B)  carbonisation
C)  Can Not Say
D)  None of the above

Correct Answer :   carbonisation

115 .
Which of the following is correct?
A)  Absolute pressure = Gauge pressure + Atmospheric pressure
A)  
B)  Gauge pressure = Absolute pressure + Atmospheric pressure
B)  
C)  Atmospheric pressure = Absolute pressure + Gauge pressure
C)  
D)  Absolute pressure = Gauge pressure - Atmospheric pressure
D)  

Correct Answer :   Absolute pressure = Gauge pressure + Atmospheric pressure

116 .
The distillation carried out in such a way that the liquid with the lowest boiling point is first evaporated and recondensed, then the liquid with the next higher boiling point is then evaporated and recondensed, and so on until all the available liquid fuels are separately recovered in the sequence of their boiling points. Such a process is called
A)  cracking
A)  
B)  carbonisation
B)  
C)  full distillation
C)  
D)  fractional distillation
D)  

Correct Answer :   fractional distillation

117 .
The general gas equation is (where p = Pressure, v = Volume, m = mass, T = Absolute temperature, and R = Gas constant)
A)  pvm = C
A)  
B)  pv = mRT
B)  
C)  pv = RTm
C)  
D)  pv = (RT)m
D)  

Correct Answer :   pv = mRT

118 .
One kg of hydrogen requires 8 kg of oxygen and produces
A)  3 kg of water
B)  7 kg of water
C)  8 kg of water
D)  9 kg of water

Correct Answer :   9 kg of water

119 .
The gas constant (R) is equal to the
A)  sum of two specific heats
B)  ratio of two specific heats
C)  difference of two specific heats
D)  product of two specific heats

Correct Answer :   difference of two specific heats

120 .
The work ratio of simple gas turbine cycle depends upon
A)  pressure ratio
B)  minimum cycle temperature
C)  maximum cycle temperature
D)  All of the above

Correct Answer :   All of the above

121 .
The unit of power in S.I. units is kilowatt.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

122 .
The reading of the pressure gauge fitted on a vessel is 25 bar. The atmospheric pressure is 1.03 bar and the value of 'g' is 9.81 m/s². The absolute pressure in the vessel is
A)  34.81 bar
A)  
B)  26.03 bar
B)  
C)  25 bar
C)  
D)  23.97 bar
D)  

Correct Answer :   26.03 bar

123 .
Otto cycle consists of
A)  two constant volume and two isentropic processes
B)  two constant volume and two isothermal processes
C)  two constant pressure and two isentropic processes
D)  one constant pressure, one constant volume and two isentropic processes

Correct Answer :   two constant volume and two isentropic processes

124 .
The increase in entropy of a system represents
A)  decrease in pressure
B)  increase in temperature
C)  increase in availability of energy
D)  degradation of energy

Correct Answer :   degradation of energy

125 .
In a free expansion process,
A)  dU = 0
A)  
B)  Q1 - 2 = 0
B)  
C)  W1 - 2 = 0
C)  
D)  All of the above
D)  

Correct Answer :   All of the above

126 .
Which of the following is chosen as the standard thermometric substance?
A)  Solid
B)  Gas
C)  Liquid
D)  None of the above

Correct Answer :   Gas

Explanation : Smallest variation is observed among different gas thermometers.

127 .
What is the magnitude of mechanical work?
A)  sum of the force and distance travelled parallel to the force
B)  sum of the force and distance travelled perpendicular to the force
C)  product of the force and distance travelled parallel to the force
D)  product of the force and distance travelled perpendicular to the force

Correct Answer :   product of the force and distance travelled parallel to the force

Explanation : The work is done by a force acting on a body moving in the force’s direction.

128 .
Which of the following gives the Mechanical efficiency of the engine?
A)  BP/IP
B)  IP/BP
C)  (BP*IP)
D)  1/(BP*IP)

Correct Answer :   BP/IP

Explanation : Brake power is less than indicated power and mechanical efficiency is given by BP/IP.

129 .
Which of the following type of motion does Shaft uses to do work?
A)  vertical motion
B)  horizontal motion
C)  rotational motion
D)  None of the above

Correct Answer :   rotational motion

Explanation : When a shaft is rotated by a motor, there is work transfer into the system.

130 .
A refrigerator with a 2 kW motor for powering the compressor gives 6000 kJ of cooling to the refrigerated space during 30 minutes of operation in a thermally insulated kitchen. Calculate the change in internal energy of the kitchen if the condenser coil behind the refrigerator rejects 8000 kJ of heat to the kitchen over the same time period.
A)  2400 kJ
A)  
B)  3600 kJ
B)  
C)  4800 kJ
C)  
D)  None of the above
D)  

Correct Answer :   3600 kJ

Explaination : QKitchen = 0 (Insulated!),
W(Electrical) = – P*∆τ = – 2 kW*30*60 sec = – 3600 kJ
(It is negative because work is done on to the system)
Change in internal energy of the kitchen (∆UKitchen) = QKitchen – WElectrical
= 0 – (–3600) = 3600 kJ.

131 .
One kg of carbon produces _____ kg of carbon dioxide.
A)  3/7
B)  7/3
C)  3/11
D)  11/3

Correct Answer :   11/3

132 .
The heat supplied to the gaS at constant volume is (where m = Mass of gas, cv = Specific heat at constant volume, cp = Specific heat at constant pressure, T2 - T1 = Rise in temperature, and R = Gas constant)
A)  mR(T2 - T1)
A)  
B)  mcv(T2 - T1)
B)  
C)  mcp(T2 - T1)
C)  
D)  mcp(T2 + T1)
D)  

Correct Answer :   mcv(T2 - T1)

133 .
Ericsson cycle consists of two constant pressure and two isothermal processes.
A)  Agree
B)  Disagree
C)  Can Not Say
D)  None of the above

Correct Answer :   Agree

134 .
The expansion ratio (r) is the ratio of (where v₁ = Volume at the beginning of expansion, and v₂ = Volume at the end of expansion)
A)  v₁/v₂
A)  
B)  v₂/v₁
B)  
C)  v₁+v₂/v₁
C)  
D)  v₁+v₂/v₂
D)  

Correct Answer :   v₂/v₁

135 .
The dual combustion cycle consists of one constant pressure, two constant volume and two isentropic processes.
A)  Agree
B)  Disagree
C)  Can Not Say
D)  None of the above

Correct Answer :   Agree

136 .
High air-fuel ratio in gas turbines
A)  increases power output
B)  do not damage turbine blades
C)  reduces exhaust temperature
D)  improves thermal efficiency

Correct Answer :   reduces exhaust temperature

137 .
For the constant pressure and heat input, the air standard efficiency of gas power cycle is in the order
A)  Dual cycle, Otto cycle, Diesel cycle
B)  Dual cycle, Diesel cycle, Otto cycle
C)  Otto cycle, Diesel cycle, Dual cycle
D)  Diesel cycle, Otto cycle, Dual cycle

Correct Answer :   Dual cycle, Diesel cycle, Otto cycle

138 .
Coal gas consists mainly of hydrogen, carbon monoxide and various hydrocarbons.
A)  Agree
B)  Disagree
C)  Can Not Say
D)  None of the above

Correct Answer :   Agree

139 .
Which of the following statement is correct?
A)  The increase in entropy is obtained from a given quantity of heat at a low temperature.
A)  
B)  The entropy represents the maximum amount of work obtainable per degree drop in temperature.
B)  
C)  The change in entropy may be regarded as a measure of the rate of the availability or unavailability of heat for transformation into work.
C)  
D)  All of the above
D)  

Correct Answer :   All of the above

140 .
According to Kelvin-Planck's statement, a perpetual motion of the __________ is impossible.
A)  first kind
B)  second kind
C)  Can Not Say
D)  None of the above

Correct Answer :   second kind

141 .
All perfect gases change in volume by 1 / 273th of its original volume at 0°C for every 1°C change in temperature, when the pressure remains constant. This statement is called
A)  Joule's law
B)  Boyle's law
C)  Gay-Lussac law
D)  Charles' law

Correct Answer :   Charles' law

142 .
A good fuel should have ____ ignition point.
A)  low
B)  high
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   low

143 .
The value of one bar (in S. I. units) is equal to
A)  1 x 10² N/m²
B)  1 x 10³ N/m²
C)  1 x 10⁴ N/m²
D)  1 x 10⁵ N/m²

Correct Answer :   1 x 10⁵ N/m²

144 .
If the carbon content in the bituminous coal is 78 to 81%, it is said to be coking bituminous coal.
A)  Agree
B)  Disagree
C)  Can Not Say
D)  None of the above

Correct Answer :   Disagree

145 .
When a perfect gas is expanded through an aperture of minute dimensions, the process is known as
A)  adiabatic process
B)  isothermal process
C)  throttling process
D)  free expansion process

Correct Answer :   throttling process

146 .
The atomic mass of nitrogen is __________ oxygen.
A)  less than
B)  equal to
C)  more than
D)  None of the above

Correct Answer :   less than

147 .
The kinetic energy per kg molecule of any gas at absolute temperature T is equal to (where Ru = Universal gas constant)
A)  Ru x T
A)  
B)  2 Ru x T
B)  
C)  3 Ru x T
C)  
D)  1.5 Ru x T
D)  

Correct Answer :   1.5 Ru x T

148 .
Which of the following is an intensive property of a thermodynamic system?
A)  Mass
B)  Energy
C)  Temperature
D)  Volume

Correct Answer :   Temperature

149 .
A triatomic molecule consists of __________ atoms.
A)  one
B)  two
C)  three
D)  four

Correct Answer :   three

150 .
The heat and mechanical energies are mutually convertible. This statement was established by
A)  Boyle
B)  Joule
C)  Charles
D)  None of the above

Correct Answer :   Joule

151 .
The main cause for the irreversibility is
A)  unrestricted expansion
B)  mechanical and fluid friction
C)  heat transfer with a finite temperature difference
D)  All of the above

Correct Answer :   All of the above

152 .
A cycle consisting of __________ and two isothermal processes is known as Stirling cycle.
A)  two constant volume
B)  two isentropic
C)  two constant pressure
D)  one constant pressure, one constant volume

Correct Answer :   two constant volume

153 .
When a gas is heated, change takes place in
A)  volume
B)  pressure
C)  temperature
D)  All of the above

Correct Answer :   All of the above

154 .
The efficiency of Carnot cycle depends upon
A)  pressure ratio
B)  volume compression ratio
C)  temperature limits
D)  cut-off ratio and compression ratio

Correct Answer :   temperature limits

155 .
The gas turbine cycle with regenerator improves
A)  work ratio
B)  thermal efficiency
C)  avoids pollution
D)  None of the above

Correct Answer :   thermal efficiency

156 .
Which of the following has the highest calorific value?
A)  Peat
B)  Anthracite coal
C)  Lignite
D)  Bituminous coal

Correct Answer :   Anthracite coal

157 .
The efficiency of Stirling cycle is __________ Carnot cycle.
A)  equal to
B)  less than
C)  greater than
D)  None of the above

Correct Answer :   equal to

158 .
If the value of n = 0 in the equation pvn = C, then the process is called
A)  adiabatic process
A)  
B)  isothermal process
B)  
C)  constant volume process
C)  
D)  constant pressure process
D)  

Correct Answer :   constant pressure process

159 .
The efficiency of Diesel cycle approaches to Otto cycle efficiency when
A)  cut-off is zero
B)  cut-off is increased
C)  cut-off is decreased
D)  cut-off is constant

Correct Answer :   cut-off is zero

160 .
The entropy __________ in an irreversible cyclic process.
A)  decreases
B)  remains constant
C)  increases
D)  None of the above

Correct Answer :   increases

161 .
The ratio of specific heat at constant pressure (cp) and specific heat at constant volume (cv) is
A)  equal to one
A)  
B)  less than one
B)  
C)  greater than one
C)  
D)  None of the above
D)  

Correct Answer :   greater than one

162 .
The atomic mass of oxygen is
A)  32
B)  16
C)  14
D)  12

Correct Answer :   16

163 .
The processes occuring in open system which permit the transfer of mass to and from the system, are known as
A)  adiabatic processes
B)  non-flow processes
C)  flow processes
D)  None of the above

Correct Answer :   flow processes

164 .
The compression ratio for petrol engines is
A)  3 to 6
B)  5 to 8
C)  15 to 20
D)  20 to 30

Correct Answer :   5 to 8

165 .
Workdone in a free expansion process is
A)  zero
B)  minimum
C)  maximum
D)  positive

Correct Answer :   zero

166 .
The pressure exerted by an ideal gas is __________ of the kinetic energy of all the molecules contained in a unit volume of gas.
A)  one-half
B)  one-third
C)  two-third
D)  three-fourth

Correct Answer :   two-third

167 .
Which of the following has the minimum atomic mass?
A)  Carbon
B)  Oxygen
C)  Sulphur
D)  Nitrogen

Correct Answer :   Carbon

168 .
The heat flows from a cold body to a hot body with the aid of an external source. This statement is given by
A)  Joule
B)  Clausis
C)  Kelvin
D)  Gay-Lussac

Correct Answer :   Clausis

169 .
The isothermal and adiabatic processes are regarded as
A)  irreversible process
B)  reversible or irreversible process
C)  reversible process
D)  None of the above

Correct Answer :   reversible process

170 .
The variables which control the physical properties of a perfect gas are
A)  temperature of the gas
B)  volume occupied by the gas
C)  pressure exerted by the gas
D)  All of the above

Correct Answer :   All of the above

171 .
Which of the following is the correct statement?
A)  For a given compression ratio, Diesel cycle is more efficient than Otto cycle.
A)  
B)  For a given compression ratio, Otto cycle is more efficient than Diesel cycle.
B)  
C)  The efficiency of Otto or Diessel cycle has nothing to do with compressioin ratio.
C)  
D)  For a given compression ratio, both Otto and Diesel cycles have the same efficiency.
D)  

Correct Answer :   For a given compression ratio, Otto cycle is more efficient than Diesel cycle.

172 .
The fuel mostly used in cement industry and in metallurgical processes is
A)  coke
B)  wood charcoal
C)  bituminous coke
D)  pulverised coal

Correct Answer :   pulverised coal

173 .
The heating of gas at constant volume is governed by
A)  Gay-Lussac law
B)  Boyle's law
C)  Charles' law
D)  Avogadro's law

Correct Answer :   Gay-Lussac law

174 .
The temperature at which the volume of a gas becomes zero is called
A)  absolute temperature
B)  absolute zero temperature
C)  absolute scale of temperature
D)  None of the above

Correct Answer :   absolute zero temperature

175 .
At 15°C, a steel pot with a 5 mm thick bottom is filled with liquid water (conductivity 50 W/m K). The pot has a 10 cm radius and is now placed on a stove with a heat transmission of 250 W. Calculate the temperature on the bottom of the outer pot assuming the inner surface is 15°C.
A)  15.8°C
A)  
B)  16.8°C
B)  
C)  18.8°C
C)  
D)  19.8°C
D)  

Correct Answer :   15.8°C

Explaination : Steady conduction, Q = k A ∆T/∆x ⇒ ∆Τ = Q ∆x / kΑ
∆T = 250 × 0.005/(50 × π/4 × 0.22) = 0.796
T = 15 + 0.796 = 15.8°C.

176 .
Heat flow into a system is ____, and heat flow out of the system is ________
A)  positive, positive
B)  negative, negative
C)  positive, negative
D)  negative, positive

Correct Answer :   positive, negative

Explanation : The direction of heat transfer is taken from the high-temperature system to the low-temperature system.

177 .
One kg of carbon monoxide requires 4/7 kg of oxygen and produces
A)  7/3 kg of carbon monoxide gas
B)  8/3 kg of carbon monoxide gas
C)  11/3 kg of carbon dioxide gas
D)  11/7 kg of carbon dioxide gas

Correct Answer :   11/7 kg of carbon dioxide gas

178 .
The gas in cooling chamber of a closed cycle gas turbine is cooled at
A)  constant pressure
B)  constant volume
C)  constant temperature
D)  None of the above

Correct Answer :   constant pressure

179 .
The molecular mass expresssed in gram (i.e. 1 g - mole) of all gases, at N. T. P., occupies a volume of
A)  224 litres
B)  22.4 litres
C)  2.24 litres
D)  0.224 litres

Correct Answer :   22.4 litres

180 .
The absolute zero pressure will be
A)  at sea level
B)  at the centre of the earth
C)  at the temperature of - 273 K
D)  when molecular momentum of the system becomes zero

Correct Answer :   when molecular momentum of the system becomes zero

181 .
What does (m*g*z) give?
A)  macroscopic kinetic energy
B)  microscopic kinetic energy
C)  macroscopic potential energy
D)  microscopic potential energy

Correct Answer :   macroscopic potential energy

Explanation : The above formula gives the macroscopic potential energy of the fluid element by virtue of its position.

182 .
The enthalpy and internal energy are the function of temperature for
A)  water
B)  steam
C)  ideal gas
D)  all gases

Correct Answer :   ideal gas

Explanation : The enthalpy of an ideal gas depends only on the temperature because the internal energy of an ideal gas depends only on the temperature.

183 .
In which of the following systems does mass transfer occur across the system boundary?
A)  open system
B)  closed system
C)  isolated system
D)  None of the above

Correct Answer :   open system

Explanation : Basic definition of an open system.

184 .
The general gas energy equation is (where Q1 - 2 = Heat supplied, dU = Change in internal energy, and W1 - 2 = Work done in heat units)
A)  Q1 - 2 = dU + W1 - 2
A)  
B)  Q1 - 2 = dU - W1 - 2
B)  
C)  Q1 - 2= dU/W1 - 2
C)  
D)  Q1 - 2 = dU x W1 - 2
D)  

Correct Answer :   Q1 - 2 = dU + W1 - 2

185 .
The compression ratio for Diesel engines is
A)  3 to 6
B)  5 to 8
C)  15 to 20
D)  20 to 30

Correct Answer :   15 to 20

186 .
In an isothermal process,
A)  there is no change in enthalpy
B)  there is no change in temperature
C)  there is no change in internal energy
D)  All of the above

Correct Answer :   All of the above

187 .
A mixture of gas expands from 0.03 m³ to 0.06 m³ at a constant pressure of 1 MPa and absorbs 84 kJ of heat during the process. The change in internal energy of the mixture is
A)  30 kJ
A)  
B)  54 kJ
B)  
C)  84 kJ
C)  
D)  114 kJ
D)  

Correct Answer :   54 kJ

188 .
The gas constant (R) is equal to the __________ of two specific heats.
A)  sum
B)  difference
C)  ratio
D)  product

Correct Answer :   difference

189 .
The free expansion process is __________ non-flow process.
A)  reversible
B)  irreversible
C)  Can Not Say
D)  None of the above

Correct Answer :   irreversible

190 .
Otto cycle efficiency is higher than Diesel cycle efficiency for the same compression ratio and heat input because in Otto cycle
A)  heat rejection is lower
B)  maximum temperature is higher
C)  combustion is at constant volume
D)  expansion and compression are isentropic

Correct Answer :   heat rejection is lower

191 .
Which of the following is the correct statement?
A)  All the reversible engines have the same efficiency.
A)  
B)  Irreversible engines have maximum efficiency.
B)  
C)  All the reversible and irreversible engines have the same efficiency.
C)  
D)  All engines are designed as reversible in order to obtain maximum efficiency.
D)  

Correct Answer :   Irreversible engines have maximum efficiency.

192 .
It is __________ to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work.
A)  possible
B)  impossible
C)  Can Not Say
D)  None of the above

Correct Answer :   impossible

193 .
The amount of heat generated per kg of fuel is known as
A)  heat energy
B)  lower calorific value
C)  calorific value
D)  higher calorific value

Correct Answer :   calorific value

194 .
The entropy may be expressed as a function of
A)  heat and work
B)  temperature and volume
C)  pressure and temperature
D)  All of the above

Correct Answer :   pressure and temperature

195 .
Carnot cycle has maximum efficiency for
A)  petrol engine
B)  diesel engine
C)  irreversible engine
D)  reversible engine

Correct Answer :   reversible engine

196 .
A close cycle gas turbine gives __________ efficiency as compared to an open cycle gas turbine.
A)  lower
B)  higher
C)  same
D)  None of the above

Correct Answer :   higher

197 .
The efficiency of the dual combustion cycle for the same compression ratio, is __________ Diesel cycle.
A)  greater than
B)  equal to
C)  less than
D)  None of the above

Correct Answer :   greater than

198 .
Charles' law states that all perfect gases change in volume by ______ of its original volume at 0° C for every 1° C change in temperature, when pressure remains constant.
A)  1/27th
B)  1/93th
C)  1/173th
D)  1/273th

Correct Answer :   1/273th

199 .
The calorific value of gaseous fuel is expressed in
A)  kJ
B)  kJ/kg
C)  kJ/m²
D)  kJ/m³

Correct Answer :   kJ/m³

200 .
When more than one fluid stream enters or leaves the control volume, which of the following type of balance is taken?
A)  mass balance
B)  energy balance
C)  mass balance and energy balance
D)  None of the above

Correct Answer :   mass balance and energy balance

201 .
Fluid flow through which of the following throttles the flow?
A)  orifice
B)  porous plug
C)  partially opened valve
D)  All of the above

Correct Answer :   All of the above

202 .
Rate of energy increase within the control volume is given by
A)  rate of energy inflow + rate of energy outflow
B)  rate of energy inflow – rate of energy outflow
C)  rate of energy inflow * rate of energy outflow
D)  rate of energy inflow / rate of energy outflow

Correct Answer :   rate of energy inflow – rate of energy outflow

Explanation : The rate of accumulation of energy within the control volume is equal to the net energy flow across the control surface.

203 .
A cylinder/piston contains 1kg methane gas at 100 kPa, 20°C. The gas is compressed reversibly to a pressure of 800 kPa. What is the work required if the process is isothermal?
A)  -116.0 kJ
A)  
B)  -216.0 kJ
B)  
C)  -316.0 kJ
C)  
D)  -416.0 kJ
D)  

Correct Answer :   -316.0 kJ

Explaination : Process: T = constant. For ideal gas then u2 = u1 1W2 = 1Q2 and ∫ dQ/T = 1Q2/T
1W2 = 1Q2 = mT(s2 – s1) = -mRT ln(P2/P1)
= -0.51835× 293.2 ln(800/100) = -316.0 kJ.

204 .
Which of the following is true for a discharging tank?
A)  dQ=0
B)  the process is adiabatic
C)  the process is quasi-static
D)  All of the above

Correct Answer :   All of the above

Explanation : Applying the first law to the control volume and dW=0, dm=0 and KE and PE of the fluid are assumed to be small.

205 .
The change of entropy, when heat is absorbed by the gas, is
A)  positive
B)  negative
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   positive

206 .
The general law for the expansion or compression of gases, is
A)  pv = C
A)  
B)  pv = m R T
B)  
C)  pvn = C
C)  
D)  pvγ = C
D)  

Correct Answer :   pvn = C

207 .
The heat energy stored in the gas and used for raising the temperature of the gas is known as
A)  kinetic energy
B)  external energy
C)  internal energy
D)  molecular energy

Correct Answer :   internal energy

208 .
When the gas is heated at constant pressure, the heat supplied
A)  increases the internal energy of the gas
B)  increases the temperature of the gas
C)  does some external work during expansion
D)  Both (B) and (C)

Correct Answer :   Both (B) and (C)

209 .
The __________ states that change of internal energy of a perfect gas is directly proportional to the change of temperature.
A)  Boyle's law
B)  Joule's law
C)  Charle's law
D)  Gay-Lussac law

Correct Answer :   Joule's law

210 .
A piston/cylinder contains carbon dioxide at 300 kPa, 100°C with a volume of 0.2 m^3. Weights are added at such a rate that the gas compresses according to the relation PV^1.2 = constant to a final temperature of 200°C. Find the work done during the process.
A)  60.4 kJ
A)  
B)  -50.4 kJ
B)  
C)  80.4 kJ
C)  
D)  -80.4 kJ
D)  

Correct Answer :   -80.4 kJ

Explaination : For the Polytropic process PVn = constant
1W2 = ∫PdV = (P2V2 – P1V1)/(1 – n )
Assuming ideal gas, PV = mRT
But mR = P1V1/T1 = 300 × 0.2/373.15 = 0.1608 kJ/K
1W2 = 0.1608(473.15 – 373.15)/(1 – 1.2) = -80.4 kJ.

211 .
Which of the following statements are true for a mechanical energy reservoir(MER)?
A)  stores work as KE or PE
B)  all processes within an MER are quasi-static
C)  it is a large body enclosed by an adiabatic impermeable wall
D)  All of the above

Correct Answer :   All of the above

212 .
Which of the following is true according to Clausius statement?
A)  it is impossible to construct a device that can transfer heat from a cooler body to a hotter body without any effect
B)  it is possible to construct a device that can transfer heat from a cooler body to a hotter body without any effect
C)  it is impossible to construct a device that can transfer heat from a hotter body to a cooler body without any effect
D)  None of the above

Correct Answer :   it is impossible to construct a device that can transfer heat from a cooler body to a hotter body without any effect

213 .
What is the relationship between Kelvin-Planck's and Clausius' statements?
A)  not connected to each other
B)  violation of one doesn’t violate the other
C)  virtually two parallel statements of the second law
D)  None of the above

Correct Answer :   virtually two parallel statements of the second law

214 .
One Joule (J) is equal to
A)  1 N-m
B)  1 kN-m
C)  10 N-m/s
D)  10 kN-m/s

Correct Answer :   1 N-m

215 .
When the expansion or compression takes place according to the law pvn = C, the process is known as
A)  adiabatic process
B)  polytropic process
C)  isothermal process
D)  hyperbolic process

Correct Answer :   polytropic process

216 .
An open cycle gas turbine works on
A)  Otto cycle
B)  Joule's cycle
C)  Carnot cycle
D)  Stirling cycle

Correct Answer :   Joule's cycle

217 .
The state of a substance whose evaporation from its liquid state is complete, is known as
A)  air
B)  steam
C)  vapour
D)  perfect gas

Correct Answer :   perfect gas

218 .
For the same compression ratio, the efficiency of dual combustion cycle is
A)  less than Diesel cycle
B)  greater than Diesel cycle
C)  greater than Diesel cycle and less than Otto cycle
D)  less than Diesel cycle and greater than Otto cycle

Correct Answer :   greater than Diesel cycle and less than Otto cycle

219 .
Coke is produced
A)  when coal is first dried and then crushed to a fine powder by pulverising machine
B)  by heating wood with a limited supply of air to a temperature not less than 280°C
C)  from the finely ground coal by moulding under pressure with or without a binding material
D)  when coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel

Correct Answer :   when coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel

220 .
In an irreversible process, there is a
A)  loss of heat
B)  gain of heat
C)  no loss of heat
D)  no gain of heat

Correct Answer :   loss of heat

221 .
An adiabatic process is one in which
A)  no heat enters or leaves the gas
B)  the temperature of the gas changes
C)  the change in internal energy is equal to the mechanical workdone
D)  All of the above

Correct Answer :   All of the above

222 .
Which of the following is the lightest and most volatile liquid fuel?
A)  Kerosene
B)  Gasoline
C)  Fuel oil
D)  None of the above

Correct Answer :   Gasoline

223 .
A cycle consisting of one constant pressure, one constant volume and two isentropic processes is known as
A)  Otto cycle
B)  Carnot cycle
C)  Diesel cycle
D)  Stirling cycle

Correct Answer :   Diesel cycle

224 .
The efficiency and work ratio of a simple gas turbine cycle are
A)  low
B)  very low
C)  high
D)  very high

Correct Answer :   very low

225 .
The amount of heat required to raise the temperature of the unit mass of gas through one degree at constant volume, is called
A)  kilo Joule
B)  specific heat at constant pressure
C)  specific heat at constant volume
D)  None of the above

Correct Answer :   specific heat at constant volume

226 .
Which of the following causes irreversibility?
A)  inelasticity
B)  friction, viscosity
C)  electrical resistance, magnetic hysteresis
D)  All of the above

Correct Answer :   All of the above

Explanation : These effects are known as dissipative effects.

227 .
The reversed heat engine takes heat from a ___ temperature body, then discharges it to a ___ temperature body and ___ an inward flow of the network.
A)  low, high, receives
B)  low, high, gives
C)  high, low, gives
D)  high, low, receives

Correct Answer :   low, high, receives

Explanation : In a reversed heat engine, the magnitude of energy transfers remains the same and only directions change.

228 .
If a system undergoes a reversible isothermal process without transfer of heat, the temperature at which this process takes place is called
A)  triple point of water
B)  absolute zero
C)  boiling point of water
D)  None of the above

Correct Answer :   absolute zero

Explanation : The smallest possible value of Q which is the amount of heat supply is zero and the corresponding temperature is zero.

229 .
Which of the following is known as the inequality of Clausius?
A)  cyclic integral of dW/T<=0
A)  
B)  cyclic integral of dQ/T>=0
B)  
C)  cyclic integral of dQ/T<=0
C)  
D)  cyclic integral of dW/T>=0
D)  

Correct Answer :   cyclic integral of dQ/T<=0

230 .
Which of the following properties describe entropy?
A)  path function, extensive property
B)  point function, extensive property
C)  path function, intensive property
D)  point function, intensive property

Correct Answer :   point function, extensive property

231 .
Which of the following statement is true?
A)  for reversible adiabatic process, S=constant
B)  for reversible isothermal heat transfer, Q=t(Sf-Si)
C)  both of the mentioned
D)  None of the above

Correct Answer :   both of the mentioned

232 .
The principal constituents of a fuel are
A)  carbon and hydrogen
B)  sulphur and oxygen
C)  oxygen and hydrogen
D)  sulphur and hydrogen

Correct Answer :   carbon and hydrogen

233 .
When a gas is heated at constant pressure
A)  its temperature will increase
B)  its volume will increase
C)  Both (A) and (B)
D)  neither temperature not volume will increase

Correct Answer :   Both (A) and (B)

234 .
Which of the following gas has the highest calorific value?
A)  Mond gas
B)  Producer gas
C)  Blast furnace gas
D)  Coal gas

Correct Answer :   Coal gas

235 .
As per Charles' law, the volume of a given mass of a perfect gas varies __________ as its absolute temperature, when the absolute pressure remains constant.
A)  indirectly
B)  directly
C)  Can Not Say
D)  None of the above

Correct Answer :   directly

236 .
When the gas is cooled at constant pressure,
A)  its temperature increases but volume decreases
B)  its volume increases but temperature decreases
C)  both temperature and volume increases
D)  both temperature and volume decreases

Correct Answer :   both temperature and volume decreases

237 .
The oxygen atom is __________ times heavier than the hydrogen atom.
A)  16
B)  8
C)  4
D)  2

Correct Answer :   16

238 .
The entropy of an isolated system can never ____
A)  be zero
B)  increase
C)  decrease
D)  None of the above

Correct Answer :   decrease

Explanation : The entropy of an isolated system always increases and remains constant only when the process is reversible.

239 .
A car uses power of 25 hp for a one hour in a round trip. Thermal efficiency of 35% can be assumed? Find the change in entropy if we assume ambient at 20°C.
A)  254.1 kJ/K
B)  354.1 kJ/K
C)  654.1 kJ/K
D)  554.1 kJ/K

Correct Answer :   654.1 kJ/K

Explanation : E = ⌠ W dt = 25 hp × 0.7457 (kW/hp) × 3600 s = 67 113 kJ = η Q
Q = E / η = 67 113 / 0.35 = 191 751 kJ
∆S = Q / T = 191 751 / 293.15 = 654.1 kJ/K.

240 .
If heat Q flows reversibly from the system to the surroundings at To, what will be the effect on entropy?
A)  entropy of the system is reduced by Q/To
B)  system has lost entropy to the surroundings
C)  entropy increase of the surroundings is Q/To
D)  All of the above

Correct Answer :   All of the above

Explanation : We can say that there is entropy transfer from the system to the surroundings along with heat flow.

241 .
Otto cycle is also known as
A)  constant pressure cycle
B)  constant volume cycle
C)  constant temperature cycle
D)  constant temperature and pressure cycle

Correct Answer :   constant volume cycle

242 .
The efficiency of a dual combustion cycle __________ upon cut-off ratio.
A)  depends
B)  does not depend
C)  Can Not Say
D)  None of the above

Correct Answer :   depends

243 .
Producer gas is obtained by
A)  carbonisation of bituminous coal
B)  passing steam over incandescent coke
C)  passing air and a large amount of steam over waste coal at about 650°C
D)  partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast

Correct Answer :   partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast

244 .
For a perfect gas, according to Boyle's law (where p = Absolute pressure, v = Volume, and T = Absolute temperature)
A)  v/T = constant, if p is kept constant
B)  T/p = constant, if v is kept constant
C)  p v = constant, if T is kept constant
D)  p/T = constant, if v is kept constant

Correct Answer :   p v = constant, if T is kept constant

245 .
The efficiency of Diesel cycle depends upon
A)  pressure ratio
B)  compression ratio
C)  temperature limits
D)  cut-off ratio and compression ratio

Correct Answer :   cut-off ratio and compression ratio

246 .
Kelvin-Planck's law deals with
A)  conservation of heat
B)  conversion of heat into work
C)  conservation of work
D)  conversion of work into heat

Correct Answer :   conversion of heat into work

247 .
Those substances which have so far not been resolved by any means into other substances of simpler form are called
A)  elements
B)  atoms
C)  compounds
D)  molecules

Correct Answer :   elements

248 .
The measurement of a thermodynamic property known as temperature is based on
A)  First law of thermodynamics
B)  Second law of thermodynamics
C)  Zeroth law of thermodynamics
D)  None of the above

Correct Answer :   Zeroth law of thermodynamics

249 .
One molecule of oxygen is ____ times heavier than the hydrogen atom.
A)  12
B)  14
C)  16
D)  32

Correct Answer :   32

250 .
The heat and work are mutually convertible. This statement is called __________ law of thermodynamics.
A)  Zeroth
B)  First
C)  Second
D)  None of the above

Correct Answer :   First

251 .
The mass of flue gas per kg of fuel is the ratio of the
A)  mass of oxygen in 1 kg of flue gas to the mass of oxygen in 1 kg of fuel
B)  mass of carbon in 1 kg of flue gas to the mass of carbon in 1 kg of fuel
C)  mass of oxygen in 1 kg of fuel to the mass of oxygen in 1 kg of flue gas
D)  mass of carbon in 1 kg of fuel to the mass of carbon in 1 kg of flue gas

Correct Answer :   mass of carbon in 1 kg of flue gas to the mass of carbon in 1 kg of fuel

252 .
Kerosene is distilled at
A)  220° to 345°C
B)  345° to 470°C
C)  470° to 550°C
D)  None of the above

Correct Answer :   220° to 345°C

253 .
The efficiency of the Carnot cycle may be increased by
A)  increasing the lowest temperature
B)  decreasing the highest temperature
C)  increasing the highest temperature
D)  keeping the lowest temperature constant

Correct Answer :   increasing the highest temperature

254 .
The bomb calorimeter is used for finding the __________ calorific value of solid and liquid fuels.
A)  higher
B)  lower
C)  Can Not Say
D)  None of the above

Correct Answer :   higher

255 .
The __________ is obtained when carbonisation of coal is carried out at 500° to 700° C.
A)  hard coke
B)  soft coke
C)  bituminous coal
D)  pulverised coal

Correct Answer :   soft coke

256 .
Equal volumes of all gases, at the same temperature and pressure, contain equal number of molecules. This statement is called Avogadro's law.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

257 .
Which of the following is true?
A)  Q for reversible < Q for irreversible and work for reversible < work for irreversible
A)  
B)  Q for reversible > Q for irreversible and work for reversible < work for irreversible
B)  
C)  Q for reversible < Q for irreversible and work for reversible > work for irreversible
C)  
D)  Q for reversible > Q for irreversible and work for reversible > work for irreversible
D)  

Correct Answer :   Q for reversible > Q for irreversible and work for reversible > work for irreversible

Explaination : This is because, Q for reversible=(To)*(S2-S1) and Q for irreversible<(To)*(S1-S2).

258 .
The available energy of a system ___ as its temperature or pressure decreases and approaches that of the surroundings.
A)  increases
B)  decreases
C)  remains constant
D)  None of the above

Correct Answer :   decreases

259 .
The entropy of any closed system can increase in which of the following way?
A)  dissipative effects or internal irreversibilities
B)  by heat interaction in which there is entropy transfer
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   Both (A) and (B)

260 .
When a system changes its state from one equilibrium state to another equilibrium state, then the path of successive states through which the system has passed, is known as
A)  thermodynamic law
B)  thermodynamic cycle
C)  thermodynamic process
D)  None of the above

Correct Answer :   thermodynamic process

261 .
The ultimate analysis of coal consists of the determination of the percentage of
A)  carbon
B)  sulphur and ash
C)  hydrogen and nitrogen
D)  All of the above

Correct Answer :   All of the above

262 .
The fuel mostly used in blast furnace for extracting pig iron from iron ores is
A)  hard coke
B)  soft coke
C)  pulverised coal
D)  bituminous coal

Correct Answer :   hard coke

263 .
The ratio of root mean square velocity to average velocity of gas molecules at a particular temperature is
A)  0.086
B)  1.086
C)  3.086
D)  4.086

Correct Answer :   1.086

264 .
The throttling process is __________ process.
A)  reversible
B)  irreversible
C)  reversible or irreversible
D)  None of the above

Correct Answer :   irreversible

265 .
In S. I. units, the value of the universal gas constant is
A)  8.314 J/kg mole-K
B)  83.14 J/kgmole-K
C)  831.4 J/kgmole-K
D)  8314 J/kgmole-K

Correct Answer :   8314 J/kgmole-K

266 .
First law of thermodynamics deals with
A)  conservation of heat
B)  conservation of mass
C)  conservation of energy
D)  conservation of momentum

Correct Answer :   conservation of energy

267 .
A hot metal piece is cooled rapidly to 25°C, removing 1000 kJ from the metal. Calculate the change of entropy if saturated liquid R-22 at −20°C absorbs the energy so that it becomes saturated vapor.
A)  0.950 kJ/K
A)  
B)  3.950 kJ/K
B)  
C)  5.950 kJ/K
C)  
D)  7.950 kJ/K
D)  

Correct Answer :   3.950 kJ/K

Explaination : R-22 boiling at -20°C; m = 1Q2 /h(fg) = 1000/220.327 = 4.539 kg
∆S(R-22) = ms(fg) = 4.539(0.8703) = 3.950 kJ/K.

268 .
Which of the following is an example of low grade energy?
A)  heat or thermal energy
B)  heat from combustion of fossil fuel
C)  heat from nuclear fission or fusion
D)  All of the above

Correct Answer :   All of the above

269 .
The entropy change of a system between two identifiable equilibrium state is ___ when the intervening process is reversible or change of state is irreversible.
A)  same
B)  different
C)  depends on the process
D)  None of the above

Correct Answer :   same

270 .
When work is dissipated into internal energy, what is the change in the disorderly motion of molecules.
A)  increases
B)  decreases
C)  remains the same
D)  None of the above

Correct Answer :   increases

Explanation : We know that increase in internal energy causes more random motion.

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