1000+ Chemical Engineering Thermodynamics Multiple Choice Question Answer [Solved]

1. Joule-Thomson co-efficient which is defined as, ? = (?T/?P)H = 1/Cp (?H/?T)P, changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is
A. 0
B. ?
C. +ve
D. -ve
Answer : A

2. What is the ratio of adiabatic compressibility to isothermal compressibility?
A. 1
B. < 1
C. > 1
D. >> 1
Answer : B

3. A system is said to be isopiestic, if there is no __________ change.
A. Temperature
B. Pressure
C. Volume
D. None of these
Answer : B

4. Helmholtz free energy (A) is defined as
A. A = H - TS
B. A = E - TS
C. A = H + TS
D. None of these
Answer : B

5. Fugacity of a component in an ideal gas mixture is equal to the partial pressure of that component in the mixture. The fugacity of each component in a stable homogeneous solution at constant pressure and temperature __________ as its mole fraction increases.
A. Decreases
B. Decreases exponentially
C. Increases
D. Remain constant
Answer : C

6. A/an __________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.
A. Isolated
B. Closed
C. Open
D. None of these
Answer : C

7. For a single component two phase mixture, the number of independent variable properties are
A. Two
B. One
C. Zero
D. Three
Answer : B

8. Which of the following exemplifies an adiabatic process?
A. Melting of ice
B. Condensation of alcohol vapor
C. Sudden bursting of a cycle tube
D. Evaporation of water
Answer : C

9. Which of the following will increase the volume of a real gas by four times?
A. Doubling the absolute temperature as well as pressure of the gas
B. Reducing pressure to one fourth at constant temperature
C. Reducing temperature to one fourth at constant pressure
D. Reducing the temperature to half and doubling the pressure
Answer : B

10. Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = C_p/C_v = 7/5) and the process to be reversible, is
A. 300 × (3^2/7)
B. 300 × (3^3/5)
C. 300 × (33^3/7)
D. 300 × (3^5/7)
Answer : A

11. The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is
A. R log_e 4
B. R log₁₀ 4
C. C_v log₁₀ 4
D. C_v log_e 4
Answer : A

12. Water on heating from 1 to 4°C
A. Contracts
B. Expands
C. Has same volume
D. May contract or expand
Answer : A

13. Enthalpy 'H' is defined as
A. H = E - PV
B. H = F - TS
C. H - E = PV
D. None of these
Answer : C

14. Pick out the correct equation relating 'F' and 'A'.
A. F = A + PV
B. F = E + A
C. F = A - TS
D. F = A + TS
Answer : A

15. d_W and d_q are not the exact differential, because q and W are
A. State functions
B. Path functions
C. Intensive properties
D. Extensive properties
Answer : B

16. What is the degree of freedom for two miscible (non-reacting) substances in vapor-liquid equilibrium forming an azeotrope?
A. 0
B. 1
C. 2
D. 3
Answer : C

17. Trouton's ratio of __________ liquids is calculated using Kistyakowsky equation.
A. Polar
B. Non-polar
C. Both (A) & (B)
D. Neither (A) nor (B)
Answer : B

18. Isobaric process means a constant process.
A. Temperature
B. Pressure
C. Volume
D. Entropy
Answer : B

19. Pick out the wrong statement.
A. Minimum number of degree of freedom of a system is zero
B. Degree of freedom of a system containing a gaseous mixture of helium, carbon dioxide and hydrogen is 4
C. For a two phase system in equilibrium made up of four non-reacting chemical species, the number of degrees of freedom is 4
D. Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation
Answer : D

20. The change in Gibbs free energy for vaporisation of a pure substance is
A. Positive
B. Negative
C. Zero
D. May be positive or negative
Answer : C

21. Consider the process A & B shown in the figure given below: In this case, it is possible that

A. Both the processes are adiabatic
B. Both the processes are isothermal
C. Process A is isothermal while B is adiabatic
D. Process A is adiabatic while B is isothermal
Answer : C

22. Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics.
A. 1st
B. Zeroth
C. 3rd
D. None of these
Answer : B

23. The enthalpy change when ammonia gas is dissolved in water is called the heat of
A. Solution
B. Formation
C. Dilution
D. Combustion
Answer : A

24. In any spontaneous process,
A. Only F decreases
B. Only A decreases
C. Both F and A decreases
D. Both F and A increase
Answer : C

25. For multi-component multiple phases to be in equilibrium at the same pressure and temperature, the __________ of each component must be same in all phases.
A. Chemical potential
B. Fugacity
C. Both (A) and (B)
D. Neither (A) nor (B)
Answer : C

26. Which of the following is affected by the temperature?
A. Fugacity
B. Activity co-efficient
C. Free energy
D. All (A), (B) & (C)
Answer : D

27. What is the number of degrees of freedom for liquid water in equilibrium with a mixture of nitrogen and water vapor?
A. 2
B. 0
C. 3
D. 1
Answer : A

28. A gas can be liquefied by pressure alone only, when its temperature is __________ its critical temperature.
A. Less than
B. More than
C. Equal to or higher than
D. Less than or equal to
Answer : D

29. In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about __________ percent.
A. 0.25
B. 0.5
C. 0.75
D. 1
Answer : B

30. Which of the following has the minimum value of COP for a given refrigeration effect?
A. Reverse Carnot cycle
B. Ordinary vapour-compression cycle
C. Vapour-compression process with a reversible expansion engine
D. Air refrigeration cycle
Answer : D

31. What is the number of degree of freedom for a system of two miscible non-reacting species in vapor-liquid equilibrium forming an azeotrope?
A. 0
B. 2
C. 1
D. 3
Answer : C

32. Entropy of the system decreases, when
A. Snow melts into water
B. A gas expands spontaneously from high pressure to low pressure
C. Water is converted into ice
D. Both (B) & (C)
Answer : D

33. For a cyclic process, a fixed ratio between heat and work
A. Always exists
B. May exist
C. Never exists
D. Is difficult to predict
Answer : A

34. In case of a reversible process (following pvⁿ = constant), work obtained for trebling the volume (v1 = 1 m³ and v₂3 m³) is maximum, when the value of 'n' is
A. 0
B. 1
C. y = 1.44
D. 1.66
Answer : A

35. Which of the following is true for Virial equation of state?
A. Virial co-efficients are universal constants
B. Virial co-efficients 'B' represents three body interactions
C. Virial co-efficients are function of temperature only
D. For some gases, Virial equations and ideal gas equations are the same
Answer : C

36. 1st law of thermodynamics is nothing but the law of conservation of
A. Momentum
B. Mass
C. Energy
D. None of these
Answer : C

37. Throttling process is a/an __________ process.
A. Reversible and isothermal
B. Irreversible and constant enthalpy
C. Reversible and constant entropy
D. Reversible and constant enthalpy
Answer : B

38. A thermodynamic system is taken from state A to B along ACB and is brought back to A along BDA as shown below in the P-V diagram. The net work done during the complete cycle is given by the area covered by

A. P₁ACBP₂P₁
B. ACBB¹A¹A
C. ACBDA
D. ADBB¹A¹A
Answer : C

39. __________ functions are exemplified by heat and work.
A. Path
B. Point
C. State
D. None of these
Answer : A

40. A solid metallic block weighing 5 kg has an initial temperature of 500°C. 40 kg of water initially at 25°C is contained in a perfectly insulated tank. The metallic block is brought into contact with water. Both of them come to equilibrium. Specific heat of block material is 0.4 kJ.kg^-1. K^-1. Ignoring the effect of expansion and contraction and also the heat capacity to tank, the total entropy change in kJ.kg^-1, K^-1 is
A. -1.87
B. 0
C. 1.26
D. 3.91
Answer : B

41. Pick out the undesirable property for a good refrigerant.
A. High thermal conductivity
B. Low freezing point
C. Large latent heat of vaporisation
D. High viscosity
Answer : D

42. The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is
A. 0
B. +ve
C. -ve
D. ?
Answer : B

43. Which of the following behaves most closely like an ideal gas?
A. He
B. N₂
C. O₂
D. H₂
Answer : A

44. Generation of heat by friction is an example of a/an __________ change.
A. Isothermal
B. Irreversible
C. Adiabatic
D. Reversible
Answer : B

45. Extensive properties of a thermodynamic system depend upon the __________ of the system.
A. Specific volume
B. Temperature
C. Mass
D. Pressure
Answer : C

46. Pick out the wrong statement.
A. Enthalpies of all elements in their standard states are assumed to be zero
B. Combustion reactions are never endothermic in nature
C. Heat of reaction at constant volume is equal to the change in internal energy
D. Clausius-Clapeyron equation is not applicable to melting process
Answer : D

47. Number of degrees of freedom for a three phase system in equilibrium comprising of three nonreacting chemical species is
A. 2
B. 0
C. 1
D. 3
Answer : A

48. With increase in temperature, the internal energy of a substance
A. Increases
B. Decreases
C. Remains unchanged
D. May increase or decrease; depends on the substance
Answer : A

49. Which of the following is not an intensive property?
A. Volume
B. Density
C. Temperature
D. Pressure
Answer : A

50. In an ideal solution, the activity of a component equals its
A. Mole fraction
B. Fugacity at the same temperature and pressure
C. Partial pressure
D. None of these
Answer : A