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
51: What is defined as the ratio of the mass of air to the mass of fuel for a combustion process?
A. Air velocity
B. Air port pressure
C. Fuel/air ratio
D. Air-fuel ratio
E. Volume of air
52: What is the definition of air-fuel ratio?
A. The ratio of air and fuel to be burned
B. The ratio of air to fuel mixture
C. The ratio of pressure and temperature in the engine
D. The ratio of air to fuel flow
E. The ratio of the mass of air to the mass of fuel
53: What type of heat pump uses cold air as the heat source?
A. Air-source heat pumps
B. Geothermal heat pumps
C. Solar thermal energy systems
D. Ground-source heat pumps
E. Solar-powered heat pumps
54: What do air-source heat pumps use as the heat source?
A. The sun
B. Electricity
C. Gas
D. Cold outside air
E. A water heater
55: What assumption does reduce the analysis of gas power cycles to a manageable level?
A. Complete combustion assumption
B. Compression ratio
C. Air-standard assumptions
D. No assumptions made
E. Ignition timing
56: What is another name for the cycle that applies air-standard assumptions?
A. Classical cycle
B. Air-standard equation
C. Air-standard cycle
D. Modified atmospheric air-conditioning cycle
57: What type of cycle is an air-standard cycle?
A. Cycle for which the air-standard conditions are prescribed
B. Cycle for which the air-standard assumptions are applicable
C. Cycle for which the ambient temperature and pressure are specified
D. Cycle for which the air-standard parameters are specified
E. Cycle for which the power used is given by P=M*V
58: What is the law that states that the volume of a gas mixture is equal to the sum of the volumes each gas would occupy if it existed alone at the mixture temperature and pressure?
A. Boyle's Law
B. Charles's Law
C. Amagat's law
D. Avogadro's law
59: What accounts for the combustion efficiency as well as other losses such as heat losses to unheated areas and start-up and cool-down losses in buildings?
A. Mechanical ventilation
B. Windows design
C. Load factor
D. Annual fuel utilization efficiency
E. Building size
60: What can you do to express the molar mass of a mixture?
A. Convert to kilograms
B. Use molar mass calculator
C. Sum of the products
D. Volume of the mixture
E. Weight of the mixture
61: What type of air is present in the atmosphere?
A. Earth's atmosphere
B. Atmospheric air
C. Polluting air
D. Solar Atmosphere
E. Ominous air
62: What is contained in atmospheric air?
A. Pollutants
B. Particles of dust and dirt
C. Water vapour
D. Nitrogen
E. Nitrogen dioxide
63: Engine knock is the premature ignition of the fuel which produces an what?
A. Harsh knocking
B. Rumbling noise
C. Flames
D. Audible noise
E. Smoke
64: Engine knock is accompanied by what?
A. A loss of power
B. A vibration
C. A coolant leak
D. An audible noise
E. A misfire
65: Engine knock is an indication of what?
A. Premature ignition
B. Faulty piston
C. Faulty connecting rod
D. Bad timing belt
E. Defective fuel injectors
66: What is the universal gas constant divided by in the above equation?
A. The heat capacity of the mixture
B. The molar mass of nitrogen
C. The molar mass of oxygen
D. The number of moles of gas
E. The apparent molar mass of the mixture
67: What is the universal gas constant divided by in the case of the molar mass of a mixture?
A. The molar mass
B. The molality
C. The apparent molar mass
D. The proportionality constant
E. The molecular weight
68: What is the pressure applied at the nozzle discharge region?
A. Forward pressure
B. Negative pressure
C. Air pressure
D. Side pressure
E. Back pressure
69: What does the term back pressure mean?
A. The speed of the fluid in the pipe
B. The pressure exerted on a pipeline in order to maintain its flow
C. The pressure applied at the nozzle discharge region
D. The pressure developed by the pump
70: What is the ratio of the compressor work to the turbine work in gas-turbine power plants?
A. Back work ratio
B. Speed ratio
C. Inlet work ratio
D. Compressor work to turbinespeed ratio
E. Horsepower ratio
71: What is the unit of work in the back ratio of a gas turbine?
A. Shaft
B. Turbine
C. Blade
D. Compressor
E. Rotor
72: What is the unit of pressure equal to 105 Pascal?
A. Bar
B. PSI
C. Kilogram
D. Ton
E. Pascale
73: How many Bar is one millibar?
A. 10,000
B. 925
C. 0.01
D. 105
E. 1000
74: What is the name of the device that measures atmospheric pressure?
A. Barometer
B. Hygrometer
C. Thermometer
75: What does the barometer measure?
A. Humidity
B. Temperature
C. Dew point
D. Atmospheric pressure
E. Air temperature
76: What is one of the best known?
A. Beattie-Bridgeman equation of state
B. The Bohr atom
C. The periodic table
D. Bohr model of the atom
E. Kepler's laws of planetary motion
77: What is one of the more recent and very accurate equations of state?
A. Boussinesq equation of state
B. Flory equation of state
C. Benedict-Webb-Rubin equation of state
D. Poynting-Robertson-Walker equation of state
E. Kosterlitz-Thouless equation of state
78: What is the name of the more recent and very accurate equation of state?
A. Benedict-Webb-Rubin
B. Pohl-Bolander
C. Poynting-Robertson-Walker
D. Newtonian
79: What is a control volume type known by Bernoulli's equation?
A. Open
B. Steady-flow
C. Closed
D. Closed-loop system
E. Automatic control
80: What does Bernoulli's equation tell us about the conservation of momentum principle?
A. That the momentum principle does not always hold
B. For steady-flow control volumes
C. That there is no conservation of momentum in steady-flow
81: Bernoulli's equation is a form of what principle?
A. The law of conservation of energy
B. The principle of least surface area
C. The first principle of thermodynamics
D. The principle of least action
E. Conservation of momentum
82: What is an example of a vapour cycle?
A. Alkaline vapour cycle
B. Vapor-liquid-solid (VLS) cycle
C. Binary vapour cycle
D. Dry ice vapour cycle
E. Condensation vapour cycle
83: What can the condenser of a binary cycle serve as?
A. Gearbox
B. Cooling tower
C. Water heater
D. Refrigerator
E. Boiler
84: What are the large heat exchangers called that transfer heat from a source to water?
A. Boiler
B. Evaporator
C. Reactor
D. Condenser
85: What is a boiler basically?
A. A large heat exchanger
B. A machine that makes sausage
C. A metal container that holds water
D. A machine used to make coffee
E. A device to produce steam
86: What is the diameter of a piston?
A. Cylinder
B. Rod
C. Stroke
D. Bore
87: The bore of a piston is what?
A. The number of pistons in a cylinder
B. The diameter of a piston
C. The height of a piston
D. The diameter of a cylinder
88: What is the position of the piston when it forms the largest volume in the cylinder?
A. Top dead center
B. Bottom dead center
C. Between the valves
89: What is the largest volume the piston forms in the cylinder?
A. Bottom dead center
B. 2/3 the volume
C. Dead center
D. 1/2 the volume
E. Top dead center
90: What type of cycle receives heat from another?
A. Air-conditioning cycle
B. Top-down cycle
C. Cold water cycle
D. Electric generator cycle
E. Bottoming cycle
91: What is the term used to describe the real or imaginary surface that separates a system from its surroundings?
A. Boundary
B. Interface
C. Barrier
D. Screen
E. Surface
92: What is the true meaning of the word "boundary"?
A. Line that marks the edge of a finite piece of land
B. Surface that separates the system from its surroundings
C. Line that divides two different categories
D. Limit that determines how much a system can change
E. Line that divides two unequal amounts
93: What is the work associated with the expansion or compression of a gas in a piston-cylinder device?
A. Rotation work
B. Compression work
C. Boundary work
D. Work of expansion
E. Work of compression
94: What is the name of the French inventor who created the Bourdon tube?
A. Antoine Bourdon
B. Eugene Bourdon
C. Pierre Bourdon
D. Jacques-Pierre Bourdon
E. Gustave F. A. Bourdon
95: What is a term used to describe a type of pressure measurement device?
A. Thermometer
B. Catheter
C. Manometer
D. Bourdon tube
96: What do the expansion and compression processes take place in?
A. Rotating machinery
B. A power plant
C. A computer
D. A printing press
E. A gasifier
97: When was the Brayton cycle first proposed?
A. Around 1920
B. Around 1940
C. Around 1870
D. Around 1300
98: What type of cycle is the Brayton cycle?
A. Fixed
B. Open
C. Closed
D. Pneumatic
99: What is the name of the cycle that allows the transfer of heat to the high pressure air leaving the compressor from the high-temperature exhaust gas leaving the turbine?
A. Otto cycle
B. Brayton cycle
C. Carnot cycle
D. Steam cycle
100: The Btu is an example of what kind of energy unit?
A. Thermal
B. Mechanical
C. Electrical
D. Joules
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