Thermodynamics MCQs : This section focuses on the "Thermodynamics". These Multiple Choice Questions (MCQs) should be practiced to improve the Thermodynamics skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
Gas laws are applicable to
A. Gases as well as vapours
B. Gases alone and not to vapors
C. Gases and steam
D. Gases and vapours under certain conditions
Question 2
A cycle consisting of one constant pressure, one constant volume and two isentropic processes is known as
A. Carnot cycle
B. Stirling cycle
C. Otto cycle
D. Diesel cycle
Question 3
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 these
Question 4
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
Question 5
According to Gay-Lussac law for a perfect gas, p/T = constant, if v is kept constant.
A. TRUE
B. FALSE
Question 6
All the commercial liquid fuels are derived from natural petroleum (or crude oil).
A. TRUE
B. FALSE
Question 7
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
Question 8
An isothermal process is governed by
A. Boyle's law
B. Charles' law
C. Gay-Lussac law
D. Avogadro's law
Question 9
Carbonisation of coal consists of
A. drying and crushing the coal to a fine powder
B. moulding the finely ground coal under pressure with or without a binding material
C. heating the wood with a limited supply of air to temperature not less than 280°C
D. none of the above
Question 10
Coal gas is obtained by mixing coal and gas at ambient conditions.
A. Yes
B. No
Question 11
If the value of n = 0 in the equation pvn = C, then the process is called
A. constant volume process
B. adiabatic process
C. constant pressure process
D. isothermal process
Question 12
In the first law of thermodynamics, the total energy of the system remains constant.
A. TRUE
B. FALSE
Question 13
One kg of carbon monoxide requires __________ kg of oxygen to produce 11/7 kg of carbon dioxide gas.
A. All
B. 04-Jul
C. 11-Apr
D. 09-Jul
Question 14
One kg of carbon requires 4/3 kg of oxygen and produces __________ kg of carbon monoxide gas.
A. 08-Mar
B. 11-Mar
C. 11-Jul
D. 07-Mar
Question 15
Stirling and Ericsson cycles are
A. reversible cycles
B. irreversible cycles
C. semi-reversible cycles
D. quasi-static cycles
Question 16
The absolute zero temperature is taken as
A. -273°C
B. 273°C
C. 237°F
D. -237°F
Question 17
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 volume
B. specific heat at constant pressure
C. kilo Joule
D. none of these
Question 18
The atomic mass of oxygen is
A. 12
B. 14
C. 16
D. 32
Question 19
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 these
Question 20
The compression ratio for petrol engines is
A. 3 to 6
B. 5 to 8
C. 15 to 20
D. 20 to 30
Question 21
The constant pressure, constant volume and constant pvn processes are regarded as irreversible process.
A. TRUE
B. FALSE
Question 22
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
B. carbonisation
C. fractional distillation
D. full distillation
Question 23
The efficiency and work ratio of a simple gas turbine cycle are
A. low
B. very low
C. high
D. very high
Question 24
The efficiency of Diesel cycle approaches to Otto cycle efficiency when
A. cut-off is increased
B. cut-off is decreased
C. cut-off is zero
D. cut-off is constant
Question 25
The efficiency of Diesel cycle increases with
A. decrease in cut-off
B. increase in cut-off
C. constant cut-off
D. none of these
Question 26
The efficiency of Stirling cycle is __________ Carnot cycle.
A. greater than
B. less than
C. equal to
Question 27
The entropy __________ in an irreversible cyclic process.
A. remains constant
B. decreases
C. increases
Question 28
The kinetic energy of molecules of a gas becomes zero at absolute zero temperature.
A. Agree
B. Disagree
Question 29
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
Question 30
The processes occuring in open system which permit the transfer of mass to and from the system, are known as
A. flow processes
B. non-flow processes
C. adiabatic processes
D. none of these
Question 31
The ratio of specific heat at constant pressure (cp) and specific heat at constant volume (cv) is
A. equal to one
B. less than one
C. greater than one
D. none of these
Question 32
The specific heat of water is
A. 1.817
B. 2512
C. 4.187
D. none of these
Question 33
The sum of internal energy (U) and the product of pressure and volume (p.v) is known as
A. workdone
B. entropy
C. enthalpy
D. none of these
Question 34
The universal gas constant of a gas is the product of molecular mass of the gas and the gas constant.
A. Correct
B. Incorrect
Question 35
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
Question 36
The value of gas constant (R) in S. I. units is
A. 0.287 J/kgK
B. 2.87 J/kgK
C. 28.7 J/kgK
D. 287 J/kgK
Question 37
The value of specific heat at constant pressure (cp) is __________ that of at constant volume (cv).
A. less than
B. equal to
C. more than
Question 38
There is a loss of heat in an irreversible process.
A. TRUE
B. FALSE
Question 39
There is no change in internal energy in an isothermal process.
A. Correct
B. Incorrect
Question 40
Water gas is obtained by passing air and a large amount of steam over waste coal at about 650°C.
A. Correct
B. Incorrect
Question 41
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
Question 42
When cut-off ratio is __________ the efficiency of Diesel cycle approaches to Otto cycle efficiency.
A. zero
B. 01-May
C. 04-May
D. 1
Question 43
When the gas is heated at constant volume, the heat supplied increases the internal energy of the gas.
A. TRUE
B. FALSE
Question 44
Which of the following gas is mostly used in town for street and domestic lighting and heating?
A. Producer gas
B. Coal gas
C. Mond gas
D. Coke oven gas
Question 45
Which of the following has the minimum atomic mass?
A. Oxygen
B. Sulphur
C. Nitrogen
D. Carbon
Question 46
Which of the following is correct?
A. Absolute pressure = Gauge pressure + Atmospheric pressure
B. Gauge pressure = Absolute pressure + Atmospheric pressure
C. Atmospheric pressure = Absolute pressure + Gauge pressure
D. Absolute pressure = Gauge pressure - Atmospheric pressure
Question 47
Which of the following is the lightest and most volatile liquid fuel?
A. Gasoline
B. Kerosene
C. Fuel oil
Question 48
Which of the following statement is incorrect?
A. The liquid fuels consist of hydrocarbons.
B. The liquid fuels have higher calorific value than solid fuels.
C. The solid fuels have higher calorific value than liquid fuels.
D. A good fuel should have low ignition point.
Question 49
Workdone in a free expansion process is
A. zero
B. minimum
C. maximum
D. positive
Question 50
A piston/cylinder with a cross-sectional area of 0.01 m^2 is resting on the stops. With an outside pressure of 100 kPa, what should be the water pressure to lift the piston?
A. 178kPa
B. 188kPa
C. 198kPa
D. 208kPa
Question 51
A 5m^3 container is filled with 840 kg of granite (density is 2400 kg/m^3) and the rest of the volume is air (density is 1.15 kg/m^3). Find the mass of air present in the container.
A. 9.3475 kg
B. 8.3475 kg
C. 6.3475 kg
D. 5.3475 kg
Question 52
A large exhaust fan in a lab room keeps the pressure inside at 10 cm water relative vacuum to the hallway? What is the net force acting on the door measuring 1.9 m by 1.1 m?
A. 2020 N
B. 2030 N
C. 2040 N
D. 2050 N
Question 53
A piston-cylinder device initially contains air at 150 kPa and 27°C. At this state, the volume is 400 litre. The mass of the piston is such that a 350 kPa pressure is required to move it. The air is now heated until its volume has doubled. Determine work done by the air.
A. 120 kJ
B. 130 kJ
C. 100 kJ
D. 140 kJ
Question 54
A sealed rigid vessel has volume of 1 m3 and contains 2 kg of water at 100°C. The vessel is now heated. If a safety pressure valve is installed, at what pressure should the valve be set to have a maximum temperature of 200°C ?
A. 431.3 kPa
B. 531.3 kPa
C. 631.3 kPa
D. 731.3 kPa
Question 55
Calculate the change in enthalpy of carbon dioxide from 30 to 1500°C at 100 kPa at constant specific heat.
A. 2237.7 kJ/kg
B. 1637.7 kJ/kg
C. 1237.7 kJ/kg
D. 2337.7 kJ/kg
Question 56
Find the change in u for carbon dioxide between 600 K and 1200 K for a constant Cv0 value.
A. 291.8 kJ/kg
B. 391.8 kJ/kg
C. 491.8 kJ/kg
D. 591.8 kJ/kg
Question 57
One kg of diatomic Oxygen is present in a 500 L tank. Find the specific volume on both mass and mole basis.
A. 0.6 m3/kg , 0.260 m3/mole
B. 0.5 m3/kg , 0.0160 m3/mole
C. 0.56 m3/kg , 0.0215 m3/mole
D. 0.7 m3/kg , 0.0325 m3/mole
Question 58
An electrochemical reaction is always a combination of oxidation half-cell and a reduction of half-cell.
A. TRUE
B. FALSE
Question 59
What is the cathodic and anodic reactions respectively of Cu-Ag system?
A. Ag==>Ag+2+2e and Cu+2+2e==>Cu
B. Cu==>Cu+2+2e and Ag==>Ag+2+2e
C. 2Ag+1+2e==>2Ag and Cu==>Cu+2+2e
D. 2Ag==>2Ag+1+2e and Cu+2+2e==>Cu
Question 60
Which of the following diagrams shows the stability of metals over a range of pH and potential of a system?
A. Phase diagrams
B. Pourbaix diagrams
C. Phase diagrams and Pourbaix diagrams
D. Colling curves
Question 61
Which of the following is a cathode and anode respectively in the Ag-Fe system?
A. Iron (Fe) and Silver (Ag)
B. Silver (Ag) and Iron (Fe)
C. Gold (Ag) and Iron (Fe)
D. Iron (Fe) and Gold (Ag)
Question 62
Which of the following is/are the applications of modern electrode kinetic principles?
A. Anodic protection
B. Noble metal alloying
C. Methods to measure corrosion rates rapidly
D. Anodic protection, noble metal alloying and methods to measure corrosion rates rapidly
Question 63
Which of the following is/are the applications of Pourbaix diagrams?
A. Predicting the spontaneous direction of reactions
B. To reduce corrosion attack
C. To reduce corrosion attack, to predict the direction of spontaneous reaction and to estimate the composition of corrosion product
D. To estimate the composition of corrosion product
Question 64
Which of the following is/are the limitations of Pourbaix diagrams?
A. Rate of reaction is can’t be predicted
B. It neglects the impurities of working conditions
C. Stability of metallic species is predicted
D. Rate of reaction is not predicted and it neglects the impurities of working conditions
Question 65
An isentropic process is restrictive and is not feasible in real life.
A. False
B. True
Question 66
First law when expressed in terms of entropy takes the form_____
A. T ds = de – p dv
B. T ds = dh – p dv
C. T ds = de + p dv
D. T ds = dh + p dv
Question 67
Flow over a rocket outside the boundary layer is isentropic.
A. False
B. True
Question 68
For a block of ice on a plate, second law of thermodynamics says that____
A. The plate will get hotter
B. Ice will get cooler
C. Cannot give conclusive direction
D. Ice will melt
Question 69
For a calorically perfect gas, entropy is not________
A. State function
B. Conserved in a reversible process
C. A function of two thermodynamic variables
D. Zero always
Question 70
For a reversible process, which is not the correct statement?
A. No presence of viscosity
B. dw = -pdv
C. dq – pdv = de
D. Mass diffusion occurs
Question 71
Identify the incorrect source for the corresponding variables of the first law.
A. Absorbed radiation: dq
B. Squeezing of volume: dw
C. Heating: de
D. Displacement of system boundary: dq
Question 72
Specific heat for gas is almost constant in the case of_______
A. Space vehicle
B. High-temperature flow
C. Air in a desert
D. Chemically reacting flow at high- speeds
Question 73
The equation of state for a perfect gas is p = δRT, where R is______ (for air at standard conditions).
A. 287 kJ/kg.K
B. 8314 kJ/kg
C. 8.314 kJ/kgK
D. 287 J/kg.K
Question 74
The equation of the second law of thermodynamics says that____
A. Total change in entropy is always zero
B. We cannot find entropy for an irreversible process
C. Entropy change is defined as the heat added in an irreversible process
D. Entropy is a state process
Question 75
The first law of thermodynamics is proved by experiments. Select the correct choice for it.
A. de is an exact differential
B. dq is an exact differential
C. dw is an exact differential
D. The relation has been proved theoretically
Question 76
Which is not a state variable/function in the given options according to thermodynamics?
A. Temperature
B. Enthalpy
C. Functions dependent on path
D. Internal energy
Question 77
Which is the correct result according to the second law of thermodynamics?
A. Total change in entropy is always zero
B. Total change in entropy in a reversible process is always zero
C. Total change in entropy in an irreversible process is always zero
D. Total change in entropy for an irreversible process is negative
Question 78
Which is the process in which no heat exchange is there between system and surroundings and in which no dissipative phenomena occur?
A. Adiabatic process
B. Reversible process
C. Isentropic process
D. Work
Question 79
Which is the wrong result for a calorically perfect gas?
A. e=cvT
B. h=cpT
C. cp and cp are functions of T
D. For T < 1000 K, specific heats are constant
Question 80
Why is controlled oxidation needed?
A. High energy
B. Loss of products
C. Temperature
D. All of the mentioned