Thermodynamics MCQs (Mechanical Engineering)

Thermodynamics MCQs (Mechanical Engineering)

Our experts have gathered these Thermodynamics MCQs through research, and we hope that you will be able to see how much knowledge base you have for the subject of Thermodynamics by answering these multiple-choice questions.
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1: According to Gay-Lussac law for a perfect gas, p/T = constant, if v is kept constant.

A.   True

B.   False

2: All the commercial liquid fuels are derived from natural petroleum (or crude oil).

A.   True

B.   False

3: Which of the following has the minimum atomic mass?

A.   Carbon

B.   Sulphur

C.   Oxygen

D.   Nitrogen

4: The compression ratio for petrol engines is

A.   3 to 6

B.   20 to 30

C.   5 to 8

D.   15 to 20

5: 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 these

6: A cycle consisting of one constant pressure, one constant volume and two isentropic processes is known as

A.   Diesel cycle

B.   Stirling cycle

C.   Otto cycle

D.   Carnot cycle

7: In the first law of thermodynamics, the total energy of the system remains constant.

A.   False

B.   True

8: The efficiency of Diesel cycle approaches to Otto cycle efficiency when

A.   Cut-off is decreased

B.   Cut-off is constant

C.   Cut-off is increased

D.   Cut-off is zero

9: The ratio of specific heat at constant pressure (Cp) and specific heat at constant volume (Cv) is

A.   Less than one

B.   None of these

C.   Greater than one

D.   Equal to one

10: 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

11: The value of specific heat at constant pressure (Cp) is __________ that of at constant volume (Cv).

A.   More than

B.   Less than

C.   Equal to

12: Water gas is obtained by passing air and a large amount of steam over waste coal at about 650°C.

A.   Incorrect

B.   Correct

13: Workdone in a free expansion process is

A.   Zero

B.   Maximum

C.   Minimum

D.   Positive

14: The processes occuring in open system which permit the transfer of mass to and from the system, are known as

A.   Flow processes

B.   None of these

C.   Non-flow processes

D.   Adiabatic processes

15: The efficiency and work ratio of a simple gas turbine cycle are

A.   High

B.   Very high

C.   Low

D.   Very low

16: 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-third

B.   Three-fourth

C.   Two-third

D.   One-half

17: The entropy __________ in an irreversible cyclic process.

A.   Decreases

B.   Increases

C.   Remains constant

18: 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.   Carbonisation

B.   Fractional distillation

C.   Cracking

D.   Full distillation

19: There is no change in internal energy in an isothermal process.

A.   Incorrect

B.   Correct

20: The amount of heat required to raise the temperature of the unit mass of gas through one degree at constant volume, is called

A.   Specific heat at constant pressure

B.   Specific heat at cOnstant volume

C.   None of these

D.   Kilo Joule

21: As entropy in a system increases, energy in the system _________.

A.   Becomes less ordered

B.   Becomes greater ordered

C.   Greater the efficiency

D.   Conservation of energy

22: Energy cannot be _______.

A.   Transformed

B.   Destroyed

C.   Both

D.   None of these

23: Internal energy undergoes changes when there are corresponding changes in _________.

A.   Zero volume

B.   Air temperature rises (or falls) as pressure increases (or decreases).

C.   Temperature

D.   -273°C, 0 K

E.   Both increase

24: Inborn or intrinsic reflexes are ________.

A.   Always mediated by the brain

B.   Involuntary, yet may be modified by learned behavior

C.   Autonomic only

D.   Rapid, predictable, and can be learned responses

25: The internal energy of a system is always increased by __________.

A.   Adding heat to the system

B.   Having the system do work on the surroundings

C.   Withdrawing heat from the system

D.   Adding heat to the system and having the system do work on the surroundings

26: The thermodynamic processes that occur in nature ____________.

A.   Convert thermal energy into mechanical energy

B.   Lead to a more ordered state

C.   Cannot be reversed

D.   Do not conserve energy

27: Spontaneous reactions _____.

A.   Always take place at a rapid rate

B.   Are always exothermic

C.   Always release free energy

D.   Always result in increased disorder of the system

28: The entropy of an isolated system _________.

A.   Always increases or remains constant.

B.   Remains constant.

C.   Either decreases or remains constant.

D.   Always decreases

29: When the quantity q is greater than zero, __________ is added to the system.

A.   Heat

B.   Pressure

C.   Both

D.   None

30: When you click through to the end of a presentation, ________ displays.

A.   Intro Slide

B.   Blank Slide

C.   Reference Slide

D.   Any of these

31: δh for an endothermic process is ________ while δh for an exothermic process is ________.

A.   Zero, positive

B.   Zero, negative

C.   Positive, negative

D.   Negative, positive

32: The _____ law of thermodynamics states that not all energy is used because _____.

A.   First; some of the energy disperses as heat

B.   Second; some of the energy disperses as heat

C.   First; some of the energy is destroyed

D.   Second;some of the energy is destroyed

33: Air that is rapidly compressed undergoes _________.

A.   Decrease in temperature;

B.   Increase in volume;

C.   Increase in temperature;

D.   None of these

34: What is the calculated relative to the absolute reference point determined by the third law of thermodynamics?

A.   Absolute temperature

B.   Absolute pressure

C.   Absolute entropy

35: What is the calculation of entropy done relative to?

A.   The surroundings of the system

B.   The absolute reference point

C.   A system under study

D.   A Gaussian random number

E.   A system's surroundings

36: What is the ratio of the mass of water vapor to the mass of dry air?

A.   Absolute or specific humidity

B.   Relative humidity

C.   Vapor pressure

37: What is the actual pressure at a given position?

A.   Gauge pressure

B.   Atmospheric pressure

C.   Nominal pressure

D.   Absolute pressure

38: What is absolute zero pressure?

A.   Absolute vacuum

B.   Negative atmospheric pressure

C.   Absolute zero temperature

D.   Absolute zero energy

E.   Zero atmospheric pressure

39: What are the most widely used absorption refrigeration system?

A.   CO2-system

B.   Ammonia-water system

C.   Dry ice and carbon dioxide

D.   Ionic-water system

E.   Freon-system

40: What is absorbed in absorption refrigeration systems?

A.   Product

B.   Refrigerant

C.   Water

D.   Air

41: When is the theoretical maximum value of the adiabatic flame temperature attained?

A.   Near the end of combustion

B.   Complete combustion

C.   Premixed combustion

D.   In the gas phase

E.   Partial combustion

42: What is a process during which there is no heat transfer?

A.   Convective process

B.   Radiation process

C.   Adiabatic process

D.   Conduction process

43: What is the process in which a steady stream of unsaturated air is passed through a long insulated channel?

A.   Thermal expansion

B.   Ventilation process

C.   Adiabatic saturation process

D.   Venturi effect

E.   Condensation process

44: What part of the air will increase during this process?

A.   Moisture content

B.   Temperature

C.   Pressure

45: What will happen to the temperature of the air as it dries?

A.   Increase

B.   No change

C.   Decrease

D.   Remain the same

46: What is the exit temperature that air attains in the adiabatic saturation process?

A.   Absolute zero

B.   Critical temperature

C.   Boiling point

D.   Adiabatic saturation temperature

47: What is the name of the extra fuel added to the exhaust gases of the engine to provide extra thrust?

A.   Turbine Jet

B.   Injected air

C.   Nitrous Oxide

D.   Afterburner

E.   Turbocharger

48: What can an aircraft turbine engine do with its extra thrust?

A.   Fly faster than the speed of sound

B.   Fly at high altitudes

C.   Fly in formation

D.   Land on an aircraft carrier

E.   Short takeoffs

49: What are generally called in the U.S.?

A.   Washing machines

B.   Air conditioners

C.   Refrigerators

D.   Heat pumps

E.   Ceiling fans

50: What is the purpose of an air conditioner?

A.   To keep a building cool

B.   Refrigerated space

C.   To cool the air

D.   To keep the building comfortable

E.   To reduce energy consumption