Faculty of Diploma Studies – 695

Faculty of Diploma Studies – 695 Department of Mechanical Engineering - 19

Prepared By:- Prof. Jigar V. Bhalodiya (M.Tech-Thermal) 1

MCQ with Answer

Subject: Thermodynamics (3331902) Semester:3rd

Prepared by: Prof. J. V. Bhalodiya

UNIT 1 Introduction

1. Internal energy is the measure of the disorderness of the system.

(a) true

(b) false

Ans: b

2. Which of the following is not the intensive property?

a. Pressure

b. Temperature

c. Density

d. Volume

Ans: d

3. The unit of temperature in S.I. unit is

(a) Rankine

(b) Celsius

(c) Fahrenheit

(d) Kelvin

Ans: d

4. The unit of mass in S.I. unit is

(a) kilogram

(b) gram

(c) tonne

(d) quintal

Ans: a

5. The unit of time in S.I. unit is

(a) second

(b) minute

(c) hour

(d) day

Ans: a



6. The unit of length in S.I. unit is

(a) meter

(b) centimeter

(c) kilometer

(d) millimeter.

Ans: a

7. The unit of energy in S.I. unit is

(a) watt

(b) joule

(c) joule/s

(d) joule/m

Ans: b

8. Choose correct unit of Entropy.

a. Joule

b. Joule/Kelvin

c. Pascal

d. Newton

Ans: b

9. Choose correct unit of Specific Heat.

a. N/m

b. J/K

c. J/Kg.k

d. Bar

Ans: c

10. Which of the following is not a unit of temperature?

a. Celsius

b. Kelvin

c. Joule

d. Fahrenheit

Ans: c

11. Enthalpy is summation of

a. Internal energy and entropy

b. Internal energy and flow work

c. Entropy and flow work

d. Pressure and volume

Ans: b



12. 1 bar = _____ Pascal.

a. 1

b. 10^3

c. 10^5

d. 10

Ans: c

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

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

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

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

Ans: c

17. When system and its surrounding are in thermodynamic equilibrium, availability of the system becomes

a. zero

b. unity

c. maximum

d. minimum

Ans: a



18. Properties which depend on both system and surrounding are known as

a. Transport properties

b. basic properties

c. derived properties

d. Composite properties

Ans: d

19. Viscosity and thermal conductivity are transport properties.

a. true

b. false

Ans: a

20. Mixture of Water and Oil is Heterogeneous System.

a. true

b. false

Ans: a

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

Ans: c

22. No liquid can exist as liquid at

(a) – 273 °K

(b) vacuum

(c) zero pressure

(d) centre of earth

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

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

Ans: b

26. System of flowing fluid from a pipe is

a. Open system

b. close system

c. isolated system

d. Adiabatic system

Ans: a

27. Give type of boundary for the system "boiling water in closed pressure cooker".

a. Real and movable boundary

b. Imaginary and fix boundary

c. Real and fixed boundary

d. Imaginary and movable boundary

Ans: c

28. Work done by the system is taken as positive(+ve).

a. true b. false

Ans: a

29. Heat is energy in transition due to _____ difference between system and surrounding.

a. Pressure

b. Temperature

c. Volume

d. Mass

Ans: b

30. Choose correct equation of flow work.

a. P/V

b. P+V

c. PV

d. P-V

Ans: c

31. Atmospheric pressure is

a. 0.1 N/m2 b. 1.01325 bar

c. 1 pascal d. 9.81 bar

Ans: b



32. In which of the following system, energy can cross the boundary but mass can not cross the boundary?

a. Open system

b. Close system

c. Isolated System

d. Adiabatic System

Ans: b

33. Which of the following is not Extrinsic property?

a. Velocity

b. Height

c. Weight

d. Volume

Ans: d

34. An open system is one in which


(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

Ans: c

35. Everything external to the system is known as Universe.

a. true b. false

Ans: b

36. Work during expansion and compression is also known as____.

a. Shaft work

b. Flow work

c. Boundary work

d. Electric work

Ans: c

37. Heat rejected from the system taken as positive(+ve).

a. true b. false

Ans: b

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

Ans: a



39. Work done in a free expansion process is

(a) + ve

(b) -ve

(c) zero

(d) maximum

Ans: c

40. An isolated system is one in which


(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

Ans: b

41. Properties of substances like pressure, temperature and density, in thermodynamic coordinates are

(a) path functions

(b) point functions

(c) cyclic functions

(d) real functions

Ans: b

42. Which of the following quantities is not the property of the system

(a) pressure

(b) temperature

(c) specific volume

(d) heat

Ans: d

43. Mixture of ice and water form a

(a) closed system

(b) open system

(c) isolated system

(d) heterogeneous system

Ans: d

44. 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



45. Which of the following is not the intensive property

(a) pressure

(b) temperature

(c) density

(d) heat

Ans: d

46. Which of the following items is not a path function

(a) heat

(b) work

(c) kinetic energy

(d) thermal conductivity.

Ans: d

47. Heat and work are

(a) point functions

(b) extensive properties

(c) path functions

(d) intensive properties

Ans: c

48. 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

Ans: c

49. 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

Ans: a

50. One watt is equal to

(a) 1 Nm/s

(b) 1 N/mt

(c) 1 Nm/hr

(d) 1 kNm/hr

Ans: a



51. 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

Ans: c

52. Entropy change depends on

(a) heat transfer

(b) mass transfer

(c) change of temperature

(d) thermodynamic state

Ans: a

53. Measurement of temperature is based on

(a) thermodynamic properties

(b) zeroth law of thermodynamics

(c) first law of thermodynamics

(d) second law of thermodynamics

Ans: b

54. A diathermic wall is one which

(a) prevents thermal interaction

(b) permits thermal interaction

(c) encourages thermal interaction

(d) discourages thermal interaction

Ans: b

55. An adiabatic wall is one which

(a) prevents thermal interaction

(b) permits thermal interaction

(c) encourages thermal interaction

(d) discourages thermal interaction

Ans: a

56. The energy of molecular motion appears as

(a) heat

(b) potential energy

(c) surface tension

(d) friction

Ans: a



57. Calorie is a measure of

(a) specific heat

(b) quantity of heat

(c) thermal capacity

(d)entropy

Ans: b

58. I kgf/cm2 is equal to

(a) 760 mm Hg

(b) zero mm Hg

(c) 735.6 mm Hg

(d) 1 mm Hg

Ans: c

59. Barometric pressure is equal to

(a) 760 mm Hg

(b) zero mm Hg

(c) 735.6 mm Hg

(d) 1 mm Hg

Ans: a

60. One barometric pressure or 1 atmospheric pressure is equal to

(a) 1 kgf/cm2 (b) 1.033 kgf/cm2

(c) 0 kgf/cm2 (d) 1.0197 kgf/cm2

Ans: b

61. If system involves two phases, it is said to be in phase equilibrium, when ____ of each phase remain constant with respect to time.

a. mass b. volume

c. pressure d. temperature

Ans: a

62. Heat can be converted totally into work.

a. true b. false

Ans: b

63. Choose wrong statement for quasi-static process.

a. it is very slow process

b. it is very fast process

c. it is not true representation of actual process

d. during this process system remains close to thermodynamic equilibrium.

Ans: b



UNIT 2 First law of thermodynamics 1. 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

Ans: b

2. 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

Ans: d

3. 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

Ans: b

4. 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) heat and internal energy.

Ans: b

5. 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

Ans: c

6. Total heat of a substance is also known as

(a) internal energy (b) entropy

(c) thermal capacity (d) enthalpy

Ans: d



7. 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

8. 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

Ans: d

9. 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

Ans: d

10. 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

Ans: d

11. 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

Ans: b

12. A perpetual motion machine is

(a) a thermodynamic machine

(b) a non-thermodynamic machine

(c) an inefficient machine

(d) a hypothetical machine whose operation would violate the laws of thermodynamics

Ans: d



13. 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

14. Value of joule’s constant in joule/calorie

a. 0 b. 1.4868

c. 1 d. 4.1868

Ans: d

15. According to first law, stored energy of an isolated system is

a. 0 b. constant

c. 1 d. maximum

Ans: b

16. Internal energy is a path function.

a. true b. false

Ans: b

17. Choose correct statement for cyclic process of close system.

a. net change in any state property is zero.

b. algebraic sum of all energy transfer during cyclic process is zero.

c. algebraic sum of work transfer is proportional to algebraic sum of heat transfer

d. all of the above

Ans: d

18. Mathematically, 1st law for non-cyclic process of close system is

a. dQ = dU + dW

b. dU = dQ + dW

c. dW = dU + dQ

d. none of the above

19. In control mass, changes occur in

a. size and shape of boundary

b. position of system respective to observer

c. both of the above


Ans: c



20. In control volume, changes occur in

a. size and shape of boundary

b. position of system respective to observer

c. both of the above


Ans: d

21. Thermodynamic analysis of which equipment is done by control volume concept?

a. nozzle b. turbine

c. compressor d. all of the above

Ans: d

22. Choose correct condition for steady flow.

a. energy flow rates across boundary of the system should remain constant with time

b. mass flow rates across boundary of the system should remain constant with time

c. Properties at any point should remain constant with time

d. all of the above

Ans: d

23. Which property remain constant during throttling process.

a. entropy b. internal energy

c. enthalpy d. pressure

Ans: c

24. In steam turbine

a. thermal energy of steam is converted into mechanical energy

b. mechanical energy is converted into thermal energy of steam

c. mechanical energy is converted into electrical energy

d. electrical energy is converted into mechanical energy

Ans: a

25. In air compressor work is

a. zero b. positive

c. negative d. none of above

Ans: c

26. When fluid passes through Nozzle

a. kinetic energy will increase and pressure will decrease

b. kinetic energy and pressure will decrease

c. kinetic energy will decrease and pressure will increase

d. kinetic energy and pressure will increase

Ans: a



27. When fluid passes through diffuser

a. kinetic energy will increase and pressure will decrease

b. kinetic energy and pressure will decrease

c. kinetic energy will decrease and pressure will increase

d. kinetic energy and pressure will increase

Ans: c

28. During adiabatic process of a close system, work of 10 KJ is done by the system on surrounding than internal energy of the system will

a. increase by 10 KJ

b. decrease by 10 KJ

c. remains constant


Ans: b

29. During four processes of a thermodynamic cycle, heat transfer is 60 KJ, -25 KJ, -24 KJ & 6 KJ respectively. Find out net work done.

a. 17 KJ

a. -17 KJ

c. 115 KJ

d. -115 KJ

Ans: a

30. A system contains 10 kg of gas. During a process internal energy is decreased by 21.7 KJ than find change in specific internal energy.

a. 2.17 KJ/kg

b. -2.17 KJ/kg

c. 217 KJ/kg

d. -217 KJ/kg

Ans: b

31. In a boiler water enters with 798 KJ/kg enthalpy & steam leaves the boiler with 2500 KJ/kg enthalpy. Find heat transfer for unit mass of working medium.

a. 3298 KJ/kg b. -3298 KJ/kg

c. 1702 KJ/kg d. -1702 KJ/kg

Ans: c

32. During a flow process system expands from 1 m3 to 2 m3 volume at constant pressure of 3 bar. Find net work done during flow process.

a. 600 KJ b. 300 KJ

c. 150 KJ d. 900 KJ

Ans: b



33. In a Nozzle fluid enters with 1800 KJ/kg enthalpy & leaves with 1700 KJ/kg enthalpy. Find velocity of the fluid at outlet of the Nozzle.

a. 100 m/s

b. 3500 m/s

c. 447.2 m/s

d. 44.72 m/s

Ans. c



UNIT 3 Thermodynamic processes 1. Which of the following variables controls the physical properties of a perfect gas

(a) pressure

(b) temperature

(c) volume


Ans: d

2. Which of the following laws is applicable for the behavior of a perfect gas

(a) Boyle’s law

(b) Charles’s law

(c) Gay-Lussac law


Ans: d

3. 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

Ans: c

4. 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 behavior

Ans: a

5. General gas equation is

(a) PV=nRT

(b) PV=mRT

(c) PV = C

(d) PV=KiRT

Ans: b

6. According to Dalton’s law, the total pressure 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

Ans: c



7. 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) O2, N2, water vapour

(c) S02, NH3, C02, moisture

(d) 02, N2, H2, air

Ans: d

8. Superheated vapour behaves

(a) exactly as gas

(b) as steam

(c) as ordinary vapour

(d) approximately as a gas

Ans: d

9. Specific heat of air at constant pressure is equal to

(a) 0.17

(b) 0.21

(c) 0.24

(d) 1.0

Ans: c

10. Characteristic gas constant of a gas is equal to

(a) Cp x Cv

(b) Cv/Cp

(c) Cp – Cv

(d) Cp + Cv

Ans: c

11. The behavior of gases can be fully determined by

(a) 1 law

(b) 2 laws

(c) 3 laws

(d) 4 laws

Ans: d

12. The ratio of two specific heats of air is equal to

(a) 0.17

(b) 0.24

(c) 0.1

(d) 1.41

Ans: d



13. 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

Ans: b

14. The same volume of all gases would represent their

(a) densities

(b) specific weights

(c) molecular weights

(d) gas characteristic constants

Ans: c

15. 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

Ans: c

16. 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

17. 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

Ans: b

18. 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

Ans: a



19. 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) Joule’s law.

Ans: a

20. 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

Ans: b

21. 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

Ans: c

22. 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

23. 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 heat transferred

Ans: a

24. 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

Ans: b



25. 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

Ans: b

26. Solids and liquids have

(a) one value of specific heat

(b) two values of specific heat

(c) three values of specific heat

(d) no value of specific heat

Ans: a

27. 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

Ans: b

28. If value of n is infinitely large in a polytropic process pVn = C, then the process is known as constant

(a) volume (b) pressure

(c) temperature (d) enthalpy

Ans: a

29. 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

Ans: d

30. Change in enthalpy of a system is the heat supplied at

(a) constant pressure (b) constant temperature

(c) constant volume (d) constant entropy

Ans: a

31. 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

Ans: c



32. A heat exchange process in which the product of pressure and volume remains constant is known as

(a) hyperbolic process

(b) throttling process

(c) isentropic process

(d) adiabatic process

Ans: a

33. In an isothermal process, the internal energy of gas molecules

(a) increases

(b) decreases

(c) remains constant

(d) may increase/decrease depend on the properties of gas

Ans: c

34. 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

Ans: d

35. 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

Ans: c

36. 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

Ans: d

37. 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

Ans: b



38. For which of the following substances, the internal energy and enthalpy are functions of temperature only

(a) any gas

(b) saturated steam

(c) water

(d) perfect gas

Ans: d

39. 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

Ans: b

40. 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

Ans: a

41. 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

Ans: b

42. For reversible adiabatic process, change in entropy is

(a) maximum

(b) minimum

(c) zero

(d) unpredictable

Ans: c

43. 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

Ans: c



44. 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

Ans: a

45. In an isothermal process, the internal energy

(a) increases

(b) decreases

(c) remains constant

(d) first increases and then decreases

Ans: c

46. 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

Ans: c

47. 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

Ans: d

48. A piston cylinder contains air at 600 kPa, 290 K and a volume of 0.01m^3. A constant pressure process gives 54 kJ of work out. Find the final volume of the air. a) 0.05 m^3 b) 0.01 m^3 c) 0.10 m^3 d) 0.15 m^3

Ans: c



UNIT 4 Second law of thermodynamics

1. Kelvin Planck’s law deals with

(a) conservation of heat

(b) conservation of work

(c) conversion of heat into work

(d) conversion of work into heat

Ans: c

2. 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

Ans: d

3. 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

Ans: b

4. Work done is zero for the following process

(a) constant volume (b) free expansion

(c) throttling (d) all of the above

Ans: d

5.. The specific heat of air increases with increase in

(a) temperature (b) pressure

(c) both pressure and temperature (d) variation of its constituents

Ans: a

6. 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

Ans: a



7. Which of the following processes are thermodynamically reversible

(a) throttling

(b) free expansion

(c) constant volume and constant pressure

(d) isothermal and adiabatic

Ans: d

8. Which of the following processes is irreversible process

(a) isothermal (b) adiabatic

(c) throttling (d) all of the above

Ans: c

9. 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 substance should be same

(c) when beat is being rejected, temperature of cold source and working substance should be same


Ans: d

10. 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

Ans: a

11. 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

Ans: d

12. Heat is transferred to a heat engine from a furnace at a rate of 80 MW. If the rate of waste heat rejection to a nearby river is 50 MW, determine the net power output for this heat engine

a) 30 MW b) 40 MW c) 50 MW d) 60 MW

Ans: a

13. Heat is transferred to a heat engine from a furnace at a rate of 80 MW. If the rate of waste heat rejection to a nearby river is 50 MW, determine the thermal efficiency for this heat engine. a) 47.5 % b) 27.5 % c) 37.5 % d) none of the mentioned

Ans: c



14. A car engine with a power output of 50 kW has a thermal efficiency of 24 percent. Determine the fuel consumption rate of this car if the fuel has a heating value of 44,000 kJ/kg. a) 0.00273 kg/s b) 0.00373 kg/s c) 0.00473 kg/s d) 0.00573 kg/s

Ans: c

15. Food compartment of a refrigerator is maintained at 4°C by removing heat from it at a rate of 360 kJ/min. If required power input to the refrigerator is 2kW, determine coefficient of performance of the refrigerator. a) 4 b) 3 c) 2 d) 1

Ans: b

16. The food compartment of a refrigerator is maintained at 4°C by removing heat from it at a rate of 360 kJ/min. If the required power input to the refrigerator is 2kW, determine the rate of heat rejection to the room that houses the refrigerator. a) 450 kJ/min b) 460 kJ/min c) 470 kJ/min d) 480 kJ/min

Ans: d

17. A heat pump is used to meet the heating requirements of a house and maintain it at 20°C. On a day when the outdoor air temperature drops to 2°C, the house is estimated to lose heat at a rate of 80,000 kJ/h. If the heat pump under these conditions has a COP of 2.5, determine the power consumed by the heat pump. a) 32000 kJ/h b) 33000 kJ/h c) 34000 kJ/h d) 35000 kJ/h

Ans: a

18. A heat pump is used to meet the heating requirements of a house and maintain it at 20°C. On a day when the outdoor air temperature drops to 2°C, the house is estimated to lose heat at a rate of 80,000 kJ/h. If the heat pump under these conditions has a COP of 2.5, determine the rate at which heat is absorbed from the cold outdoor air. a) 32000 kJ/h b) 48000 kJ/h c) 54000 kJ/h d) 72000 kJ/h

Ans: b

19. An air-conditioner provides 1 kg/s of air at 15°C cooled from outside atmospheric air at 35°C. Estimate the amount of power needed to operate the air-conditioner. a) 1.09 kW b) 1.19 kW c) 1.29 kW d) 1.39 kW

Ans: d



20. A cyclic machine, as shown below, receives 325 kJ from a 1000 K energy reservoir. It rejects 125 kJ to a 400 K energy reservoir and the cycle produces 200kJ of work as output. Is this cycle reversible, irreversible, or impossible? a) reversible b) irreversible c) impossible d) none of the mentioned

Ans: c

21. In a cryogenic experiment you need to keep a container at -125°C although it gains 100 W due to heat transfer. What is the smallest motor you would need for a heat pump absorbing heat from the container and rejecting heat to the room at 20°C? a) 97.84 kW b) 98.84 kW c) 99.84 kW d) 95.84 kW

Ans: a

22. Which among the following is correct relation between COP of heat pump and COP of refrigerator?

a. [COP]H.P. = 1 + [COP]ref b. [COP]H.P. = 1 – [COP]ref c. [COP]H.P. = [COP]ref d. none of the above

Ans: a

23. The irreversibility of a process occurs due to

a. lack of equilibrium during the process b. involvement of dissipative effects c. either a. or b. or both d. none of the above

Ans: c

24. 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

Ans: a

25. PMM2 is the machine which violates ___________

a. Kelvin-Planck statement b. Clausius statement c. both a. and b. d. none of the above

Ans: c



26. A cyclic heat engine operates between a source temperature of 927 oC and a sink temperature of 27 oC. What will be the maximum efficiency of the heat engine?

a. 100 % b. 80 % c. 75 % d. 70 %

Ans: c

27. Match the following irreversibility (1) Mechanical irreversibility ------ (A) Refrigeration cycle (2) Thermal irreversibility --------- (B) Forming of water by combination of Hydrogen and Oxygen (3) Chemical irreversibility -------- (C) Free expansion of gas in a system (4) External irreversibility --------- (D) Melting of ice cube under the sunlight

a. (1)-(A), (2)-(B), (3)-(C), (4)-(D) b. (1)-(A), (2)-(D), (3)-(B), (4)-(C) c. (1)-(C), (2)-(D), (3)-(A), (4)-(B) d. (1)-(C), (2)-(D), (3)-(B), (4)-(A)

Ans: d

28. When a process becomes irreversible due to heat interaction between system and surrounding at the boundary due to finite temperature gradient, then the irreversibility is______

a. internal irreversibility b. external irreversibility c. mechanical irreversibility d. chemical irreversibility

Ans: b

29. The irreversibility in the system caused by friction is an example of

a. internal irreversibility b. external irreversibility c. frictional irreversibility d. chemical irreversibility

Ans: a

30. Assume that a reversible heat engine is operating between a source at T1 and a sink at T2. If T2 decreases, the efficiency of the heat engine ______

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

Ans: b

31. Any attainable value of absolute temperature is ________

a. always less than zero b. always equals to zero c. always greater than zero d. none of the above

Ans: c



32. The temperature at which a system undergoes a reversible isothermal process without transfer of heat is called as _________

a. critical temperature b. Kelvin temperature c. absolute zero temperature d. reversible temperature

Ans: c

33. To achieve a definite zero point on the Kelvin scale, we have to violate

a. first law of thermodynamics b. second law of thermodynamics c. both first law and second law of thermodynamics d. no law has to be violated

Ans: b

34. The thermometric property in the Kelvin scale is _______

a. Temperature (T) b. Work energy (W) c. Heat energy (Q) d. all of the above

Ans: c

35. The Kelvin temperature scale is independent of the certain characteristics of any substance.

a. True b. False

Ans: a

36. The efficiency of the Carnot cycle is the function of

a. temperatures (T1, T2) between which the Carnot cycle operates b. net work done (Wnet) c. heat supplied (Q1) and heat rejected (Q2) d. all of the above

Ans: a

37. Match the following group 1 items with group 2 items and select the correct option. (1) PMM1 ------------------------- (A) Heat pump (2) PMM2 ------------------------- (B) Violates statement -total energy of universe is constant (3) Reversible heat engine ---- (C) Violates Kelvin-Planck statement (4) Carnot cycle------------------ (D) Reversible process

a. (1)-(A), (2)-(B), (3)-(C), (4)-(D) b. (1)-(B), (2)-(D), (3)-(C), (4)-(A) c. (1)-(B), (2)-(C), (3)-(A), (4)-(D) d. (1)-(C), (2)-(D), (3)-(B), (4)-(A)

Ans: c



38. If a reversible heat engine A is operating between the temperature levels T1 and T2 and another reversible heat engine B of different capacity is also operating between the same temperature difference T1 and T2, then the efficiency of reversible heat engine B is

a. greater than efficiency of the reversible heat engine A b. less than the efficiency of the reversible heat engine A c. equal to the efficiency of the reversible heat engine A

d. cannot say

Ans: c

39. According to the Carnot's theorem, the efficiency of a reversible heat engine operating between a same given constant temperature source and a given constant temperature sink is

a. higher than any other irreversible heat engine b. less than any other irreversible heat engine c. equal to any other irreversible heat engine d. none of the above

Ans: a

40. A process becomes reversible when

a. it undergoes in the absence of any dissipative effect b. all the points through the path are at thermodynamic equilibrium c. it undergoes as a very slow quasi-static process d. all of the above

Ans: d

41. Which of the following is a reversed heat engine?

a. Heat pump b. Refrigerator c. both a. and b. d. none of the above

Ans: c

42. Free expansion of gas within a system is

a. a reversible process b. an irreversible process c. a quasi-static process d. none of the above

Ans: b

43. A process of application of breaks in a vehicle is

a. a reversible process b. an irreversible process c. a quasi-static process d. none of the above

Ans: b

44. All spontaneous processes are

a. reversible b. irreversible c. quasi-static d. none of the above

Ans: b



45. Considering relation between Kelvin-Planck and Clausius statement, if one statement between the two is violated then

a. other one may be or may not be violated b. other one is also violated c. other one must be correct d. none of the above

Ans: b

46. COP of a heat pump is

a. always less than infinity (COP<∞) b. always less that 1 (COP < 1) c. always equals to 1 (COP = 1) d. always equals to infinity (COP = ∞)

Ans: a

47. Considering following schematic diagram of refrigerator, the coefficient of performance (COP)refof refrigerator is given by,

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

Ans: d

48. Clausius statement is related to

a. heat engine operating in a cycle b. heat pump operating in a cycle c. both a. and b. d. none of the above

Ans: b

49. If a heat engine produces net work output by exchanging heat with only one reservoir, then the heat engine will be,

a. (PMM1) b. (PMM2) c. (PMM3) d. none of the above

Ans: b



50. It is impossible to produce a heat engine, whose sole effect is to absorb energy in the form of heat from a heat source and produce an equal amount of work. This statement is

a. Kelvin-Planck statement b. Clausius statement c. Third law of thermodynamics d. none of the above

Ans: a

51. In the heat engine cycle

a. work output is greater than heat input b. work output is less than heat input c. work output is equal to heat input d. none of the above

Ans: b

52. Which among the following is/are example/s of sink?

a. River b. Sea c. Atmosphere d. all of the above

Ans: d

53. The thermal energy reservoir from which heat is transferred to the system which works on heat engine cycle is called as

a. source b. sink c. atmosphere d. all of the above

Ans: a

54. Second law of thermodynamics defines

(a) heat (b) work

(c) enthalpy (d) entropy

Ans: d

55. For a reversible adiabatic process, the change in entropy is

(a) zero (b) minimum

(c) maximum (d) infinite

Ans: a

56. For any irreversible process the net entropy change is

(a) zero (b) positive

(c) negative (d) infinite

Ans: b

57. 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

Ans: b



UNIT 5 Thermodynamic cycles 1. Carnot cycle has maximum efficiency for

(a) reversible engine

(b) irreversible engine

(c) new engine

(d) petrol engine

Ans: a

2. Carnot cycle efficiency depends upon

(a) properties of the medium/substance used

(b) condition of engine

(c) working condition

(d) temperature range of operation

Ans: d

3. 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

Ans: b

4. An engine operates between temperatures of 900°K and T2 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

Ans: a

5. 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

Ans: d

6. 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

Ans: d



7. 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

Ans: b

8. In a Carnot cycle, heat is transferred at

(a) constant pressure

(b) constant volume

(c) constant temperature

(d) constant enthaply

Ans: c

9. 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.

Ans: c

10. Compressed air coming out from a punctured football

(a) becomes hotter

(b) becomes cooler

(c) remains at the same temperature

(d) may become hotter or cooler depending upon the humidity of the surrounding air

Ans: b

11. 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 atmospheric pressure

(c) at a pressure greater than atmospheric pressure

(d) any pressure

Ans: c

12. A sudden fall in the barometer reading is a sign of approaching

(a) fine weather

(b) rains

(c) storm

(d) cold wave

Ans: c



13. The unit of universal gas constant is

(a) watts/°K

(b) dynes/°C

(c) joule/°K

(d)erg/°K

Ans: d

14. Thermal power plant works on

(a) Carnot cycle

(b) Joule cycle

(c) Rankine cycle

(d) Otto cycle

Ans: c

15. Which of the following is an irreversible cycle

(a) Carnot

(b) Stirling

(c) Eriksson

(d) none of the above.

Ans: d

16. Otto cycle consists of following four processes

(a) two isothermals and two isentropic

(b) two isentropic and two constant volumes

(c) two isentropic, one constant volume and one constant pressure

(d) two isentropic and two constant pressures

Ans: b

17. 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

18. 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

Ans: a



19. 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

20. Carnot cycle is

(a) a reversible cycle

(b) an irreversible cycle

(c) a semi-reversible cycle

(d) a quasi-static cycle

Ans: a

21. Diesel cycle consists of following four processes


(b) two isentropic, and two constant volumes.



(e) none of the above.

Ans: c

22. 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

Ans: c

23. Stirling and Ericsson cycles are

(a) reversible cycles

(b) irreversible cycles

(c) quasi-static cycles

(d) semi-reversible cycles

Ans: a

24. A cycle consisting of two adiabatic and two constant pressure processes is known as

(a) Otto cycle (b) Ericsson cycle

(c) Joule cycle (d) Stirling cycle

Ans: c



25. Reversed joule cycle is called

(a) Carnot cycle

(b) Rankine cycle

(c) Brayton cycle

(d) Bell Coleman cycle

Ans: c

26. Brayton cycle consists of following four processes





Ans: d

27. 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

Ans: c

28. The efficiency of Diesel cycle with decrease in cut off

(a) increases

(b) decreases

(c) remains unaffected

(d) first increases and then decreases

Ans: a

29. Which of the following cycles has maximum efficiency

(a) Rankine

(b) Stirling

(c) Carnot

(d) Brayton

Ans: c

30. The ideal efficiency of a Brayton cycle without regeneration with increase in pressure ratio will

(a) increase

(b) decrease

(c) remain unchanged

(d) increase/decrease depending on application

Ans: a



31. 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

Ans: b

32. 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

33. Gas turbine cycle consists of





Ans: d

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