Mechanical Engineering -Thermodynamics Expected MCQ PDF 1 For Coal India Limited (CIL) MT Exam 2017

1)   The energy of an isolated system

a. is always decreasing
b. is always constant
c. is always increasing
d. none of the above

ANSWER: is always constant

2)   The term which can differentiate thermodynamics from other sciences is ____.

a. Pressure
b. Temperature
c. Mass
d. none of the above

ANSWER: Temperature

3)   The thermodynamic work done by the system on the surrounding is considered as ____.

a. positive
b. negative
c. neutral
d. none of the above

ANSWER: positive

4)   When the heat transfer into a system is more than the work transfer out of the system, then

a. the internal energy of the system remains constant
b. the internal energy of the system decreases
c. the internal energy of the system increases
d. none of the above

ANSWER: the internal energy of the system increases

5)   Practically heat and work are completely interchangeable forms of energy

a. True
b. False

ANSWER: False

6)   First law of thermodynamics provides

a. a statement that energy balance occurs when a system undergoes the change of state or the process
b. a statement about whether the change of state or the process is at all feasible or not
c. both a. and b.
d. none of the above

ANSWER: a statement that energy balance occurs when a system undergoes the change of state or the process

7)   The
thermodynamic cycle in which net heat is transferred to the system and a
net work is transferred from the system is called as

a. refrigeration cycle
b. heat engine cycle
c. both a. and b.
d. none of the above

ANSWER: heat engine cycle

8)   Which of the following is NOT the heat engine cycle

a. refrigerator
b. stem power plant
c. mass of gas confined in a cylinder and piston machine
d. none of the above

ANSWER: refrigerator

9)   Efficiency of heat engine cycle is the ratio of

a. total heat input to the cycle (Qin) to net work output of the cycle (Wnet)
b. net work output of the cycle (Wnet) to total heat input to the cycle (Qin)
c. net work output of the cycle (Wnet) to heat rejected from the system (Qout)
d. none of the above

ANSWER: total heat input to the cycle (Qin) to net work output of the cycle (Wnet)

10)   A thermal energy reservoir (TER) has

a. a finite heat capacity
b. an infinite heat capacity
c. a finite mass
d. none of the above

ANSWER: an infinite heat capacity

11)   Two reversible adiabatic paths

a. can intersect with each other
b. cannot intersect with each other
c. may intersect or may not intersect
d. none of the above

ANSWER: cannot intersect with each other

12)   Which property of a system is constant in reversible adiabatic process?

a. pressure
b. volume
c. temperature
d. entropy

ANSWER: entropy

13)   Thermodynamics is the study of

a. energy
b. equilibrium
c. entropy
d. none of the above

ANSWER: none of the above

14)   What is the cyclic integral of dQ/T for reversible process?

a. less than zero
b. zero
c. more than zero
d. none of the above

ANSWER: zero

15)   What is the cyclic integral of dQ/T for irreversible process?

a. less than zero
b. zero
c. more than zero
d. none of the above

ANSWER: less than zero

16)   Any
reversible path may be substituted by a reversible zigzag path between
the same end processes such that the heat transfer during this zigzag
path is equal to the heat transfer during original path. What are the
processes involved in the zigzag path?

a. reversible polytropic and isobaric process
b. reversible polytropic and isothermal process
c. reversible adiabatic and isothermal processes
d. none of the above

ANSWER: reversible adiabatic and isothermal processes

17)   When a
system is taken from state A to state B through a reversible path 1 and
again the system is taken to its initial state A from B through
different reversible path 2, then what will be the effect on entropy?

a. entropy increases
b. entropy decreases
c. entropy remains constant
d. none of the above

ANSWER: entropy remains constant

18)   What is the exergy of a system?

a. The minimum work that can be extracted from a system till it reaches thermodynamic equilibrium with its surroundings
b. The maximum work that can be extracted from a system till it reaches thermodynamic equilibrium with its surroundings
c. The maximum entropy that can be increased in a system till it reaches thermodynamic equilibrium with its surroundings
d. none of the above

ANSWER: The maximum work that can be extracted from a system till it reaches thermodynamic equilibrium with its surroundings

19)   What is the effect on quality of the energy when it is conserved?

a. the quality of the energy increases while conserving its quantity
b. the quality of the energy decreases while conserving its quantity
c. the quality of the energy remains same while conserving its quantity
d. none of the above

ANSWER: the quality of the energy decreases while conserving its quantity

20)   Which
analysis/analyses is/are required to make energy conversion or energy
conveying system more efficient?

a. First law or energy analysis
b. Second law or exergy analysis
c. Both a. and b.
d. None of the above

ANSWER: Both a. and b.

21)   What is a pure substance?

a. a homogeneous mixture of two substances of same composition
b. a substance with constant chemical composition throughout its mass
c. both a. and b.
d. none of the above

ANSWER: a substance with constant chemical composition throughout its mass

22)   A pure substance exists in

a. solid phase
b. liquid phase
c. gaseous phase
d. all of the above

ANSWER: all of the above

23)   What is a mole of a substance?

a. One mole has a mass numerically equal to half the molecular weight of the substance
b. One mole has a mass numerically equal to the molecular weight of the substance
c. One mole has a mass numerically equal to double the molecular weight of the substance
d. none of the above

ANSWER: One mole has a mass numerically equal to the molecular weight of the substance

24)   According to
the Avogadro’s law, what is the relation between volume of 1 kg mol of
oxygen and volume of 1 kg mol of nitrogen, at normal pressure and
temperature? (Mass of 1 kg mol of oxygen is 32 kg and mass of 1 kg mol
of nitrogen is 28 kg)

a. volume of 1 kg mol of oxygen is greater than that of nitrogen
b. volume of 1 kg mol of oxygen is less than that of nitrogen
c. volume of 1 kg mol of oxygen is same as that of nitrogen
d. none of the above

ANSWER: volume of 1 kg mol of oxygen is same as that of nitrogen

25)   A single phase pure substance has following properties p, V, T, S, U, H, F (Helmholtz function) and G (Gibbs function). Any one in these properties may be expressed

a. as a function of the same property
b. as a function of any one other property
c. as a function of any two other properties
d. none of the above

ANSWER: as a function of any two other properties

26)   Joule-Kelvin effect can be carried out by

a. throttling process of gas
b. Joule-Thomson expansion of gas
c. both a. and b.
d. none of the above

ANSWER: both a. and b.

27)   What will be the net change in internal energy of working fluid of power cycle over the complete cycle?

a. net change in internal energy of working fluid will be positive
b. net change in internal energy of working fluid will be negative
c. no any net change in internal energy of working fluid
d. none of the above

ANSWER: no any net change in internal energy of working fluid

28)   What is the
relation between net energy transferred to unit mass of the working
fluid as heat in the power cycle and net energy transfer as work from
the working fluid in the same power cycle, if the cycle works ideally?

a. net energy transferred to unit mass of the working fluid as heat in the power cycle is greater than net energy transfer as work from the working fluid in the same power cycle
b. net energy transferred to unit mass of the working fluid as heat in the power cycle is less than net energy transfer as work from the working fluid in the same power cycle
c. net energy transferred to unit mass of the working fluid as heat in the power cycle is equal to net energy transfer as work from the working fluid in the same power cycle
d. cannot say

ANSWER: net energy transferred to unit mass of the working fluid as heat in the power cycle is equal to net energy transfer as work from the working fluid in the same power cycle

29)   What is the formula for efficiency of vapour power cycle?

a. ηcycle = Wnet / Qin
b. ηcycle = (WT – WP) / Qin
c. ηcycle = (Qin – Qout) / Qin
d. all of the above

ANSWER: all of the above

30)   Which processes do the Rankine cycle contain?

a. two isothermal and two isochoric processes
b. two isentropic and two isobaric processes
c. two isentropic and two isothermal processes
d. two isothermal and two isobaric processes

ANSWER: two isentropic and two isobaric processes

31)   At ideal condition of vapour power cycle, reversible constant pressure heat rejection is carried out at

a. boiler
b. turbine
c. condenser
d. feed pump

ANSWER: condenser

32)   Which ideal process is carried out at the turbine in vapour power cycle?

a. reversible adiabatic compression
b. reversible adiabatic expansion
c. reversible constant pressure heat addition
d. reversible constant pressure heat rejection

ANSWER: reversible adiabatic expansion

33)   In the T-s
diagram of vapour power cycle, what is the condition of stem at the
starting of turbine expansion?

a. wet with dryness fraction 0.8
b. wet with dryness fraction 0.99
c. dry saturated
d. superheated

ANSWER: dry saturated

34)   The engines which are operating on gas power cycle are

a. cyclic
b. non-cyclic
c. either cyclic or non-cyclic
d. none of the above

ANSWER: either cyclic or non-cyclic

35)   Internal combustion engine is the example of

a. cyclic heat engine
b. non-cyclic heat engine
c. both a. and b.
d. none of the above

ANSWER: non-cyclic heat engine

36)   The cycle which consists of two reversible isotherms and two reversible isochores is called as

a. Rankine cycle
b. Carnot cycle
c. Stirling cycle
d. Ericsson cycle

ANSWER: Stirling cycle

37)   Two reversible isothermal processes and two reversible isobaric processes are carried out in

a. Rankine cycle
b. Carnot cycle
c. Stirling cycle
d. Ericsson cycle

ANSWER: Ericsson cycle

38)   Which thermodynamic cycle, for the same condition, has highest efficiency among the others?

a. Carnot cycle
b. Stirling cycle
c. Ericsson cycle
d. None. All of the above have same efficiency

ANSWER: None. All of the above have same efficiency

39)   What is the correct formula for net work done of reciprocating engine?

a. Wnet = mean effective pressure × clearance volume
b. Wnet = mean effective pressure × total volume of cylinder
c. Wnet = mean effective pressure × displacement volume
d. none of the above

ANSWER: Wnet = mean effective pressure × displacement volume

40)   What is the reason of the fact that the internal combustion engine does not complete thermodynamic cycle?

a. because every time fresh air is taken inside the engine and combustion products are thrown out of the engine
b. because permanent chemical change is undergone by the working fluid in combustion chamber
c. both a. and b.
d. none of the above

ANSWER: both a. and b.

41)   The heat pump

a. receives heat from high temperature region and discharge it to low temperature region with production of useful work
b. receives heat from low temperature region and discharge it to high temperature region with production of useful work
c. receives heat from high temperature region and discharge it to low temperature region with utilization of external work
d. receives heat from low temperature region and discharge it to high temperature region with utilization of external work

ANSWER: receives heat from low temperature region and discharge it to high temperature region with utilization of external work

42)   What is correct formula for calculating COP of heat pump?

a. [COP]H. P. = Q1 / W
b. [COP]H. P. = Q2 / W
c. [COP]H. P. = W / Q1
d. [COP]H. P. = W / Q2

ANSWER: [COP]H. P. = Q1 / W

43)   How is the COP of a refrigerator calculated?

a. [COP]Ref. = Q1 / W
b. [COP]Ref. = Q2 / W
c. [COP]Ref. = W / Q1
d. [COP]Ref. = W / Q2

ANSWER: [COP]Ref. = Q2 / W

44)   Where is main concentration in refrigeration for its calculation?

a. high temperature reservoir
b. low temperature reservoir
c. both high temperature and low temperature reservoirs
d. none of the above

ANSWER: low temperature reservoir

45)   What is the relation between [COP]H. P. = [COP]Ref.?

a. [COP]H. P. = [COP]Ref.
b. [COP]H. P. + [COP]Ref. = 1
c. [COP]H. P. – [COP]Ref. = 1
d. [COP]H. P. × [COP]Ref. = 1

ANSWER: [COP]H. P. – [COP]Ref. = 1

46)   What is the effect of decrease in temperature difference between two reservoirs of heat pump on its COP?

a. COP increases with decreases in temperature difference between two reservoirs
b. COP decreases with decreases in temperature difference between two reservoirs
c. COP does not affected by change in temperature difference between two reservoirs
d. cannot say

ANSWER: COP increases with decreases in temperature difference between two reservoirs

47)   Dry air does NOT contain

a. krypton
b. argon
c. neon
d. none of the above

ANSWER: none of the above

48)   The ratio of
partial pressure of water vapour in a mixture to the saturation
pressure of water at the same temperature of the mixture is called as

a. humidity
b. partial humidity
c. specific humidity
d. relative humidity

ANSWER: relative humidity

49)   What is the specific humidity?

a. the ratio of the mass of water vapour to the mass of the total mixture of air and water vapour
b. the ratio of the mass of dry air to the mass of the total mixture of air and water vapour
c. the ratio of the mass of dry air to the mass of water vapour in a mixture of air and water vapour
d. the ratio of the mass of water vapour to the mass of dry air in a mixture of air and water vapour

ANSWER: the ratio of the mass of water vapour to the mass of dry air in a mixture of air and water vapour

50)   The boiler in which the tubes are surrounded by hot gases is called as

a. fire tube boiler
b. water tube boiler
c. both a. and b.
d. none of the above

ANSWER: water tube boiler

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Electrical Machines Expected MCQ PDF 3 For Coal India Limited (CIL) MT Exam 2017
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