Chemical Engineering Thermodynamics 1000+ MCQ with answer for SSC CPO

1. If the vapour pressure at two temperatures of a solid phase in equilibrium with its liquid phase are known, then the latent heat of fusion can be calculated by the
A. Maxwell's equation
B. Clausius-Clapeyron Equation
C. Van Laar equation
D. Nernst Heat Theorem
Answer : B

2. A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
A. Zero
B. Positive
C. Negative
D. None of these
Answer : C

3. If the heat of solution of an ideal gas in a liquid is negative, then its solubility at a given partial pressure varies with the temperature as
A. Solubility increases as temperature increases
B. Solubility increases as temperature decreases
C. Solubility is independent of temperature
D. Solubility increases or decreases with temperature depending on the Gibbs free energy change of solution
Answer : B

4. C_v is given by
A. (?E/?T)_V
B. (?E/?V)_T
C. (?E/?P)_V
D. (?V/?T)_P
Answer : A

5. The intensive properties are
A. Molar volume, density, viscosity and boiling point
B. Refractive index and surface tension
C. Both (A) and (B)
D. None of these
Answer : C

6. If an ideal solution is formed by mixing two pure liquids in any proportion, then the __________ of mixing is zero
A. Enthalpy
B. Volume
C. Both 'a' & 'b'
D. Neither 'a' nor 'b'
Answer : C

7. Refrigeration capacity of a household refrigerator may be round about __________ tons.
A. 0.15
B. 1.5
C. 4.5
D. 6.5
Answer : A

8. The third law of thermodynamics states that the
A. Heat capacity of a crystalline solid is zero at absolute zero temperature
B. Heat transfer from low temperature to high temperature source is not possible without external work
C. Gases having same reduced properties behaves similarly
D. None of these
Answer : A

9. 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

10. Gibbs free energy of mixing at constant pressure and temperature is always
A. 0
B. ?
C. + ve
D. - ve
Answer : D

11. In a P-V diagram (for an ideal gas), an isothermal curve will coincide within adiabatic curve (through a point), when
A. C_p < C_v
B. C_p = C_v
C. C_p > C_v
D. C ? C_v
Answer : B

12. Pick out the wrong statement.
A. Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom
B. The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state
C. There is an increase in entropy, when a spontaneous change occurs in an isolated system
D. At absolute zero temperature, the heat capacity for many pure crystalline substances is zero
Answer : B

13. If we increase the pressure on a substance (which is at its triple point), then the triple point
A. Increases
B. Decreases
C. Remains unchanged
D. May increase or decrease; depends on the substance
Answer : C

14. Gibbs free energy (G) is represented by, G = H - TS, whereas Helmholtz free energy, (A) is given by, A = E - TS. Which of the following is the Gibbs-Helmholtz equation?
A. [?(G/T)/?T] = - (H/T₂)
B. [?(A/T)/?T]_V = - E/T₂
C. Both (A) and (B)
D. Neither (A) nor (B)
Answer : C

15. Joule-Thomson experiment is
A. Isobaric
B. Adiabatic
C. Isenthalpic
D. Both (B) & (C)
Answer : D

16. Partial molar free energy of an element A in solution is same as its
A. Chemical potential
B. Activity
C. Fugacity
D. Activity co-efficient
Answer : A

17. For an ideal liquid solution, which of the following is unity?
A. Activity
B. Fugacity
C. Activity co-efficient
D. Fugacity co-efficient
Answer : C

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

19. The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition.
A. Internal energy
B. Enthalpy
C. Gibbs free energy
D. Helmholtz free energy
Answer : C

20. The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called the __________ temperature.
A. Critical
B. Boyle
C. Inversion
D. Reduced
Answer : B

21. High __________ is an undesirable property for a good refrigerant.
A. Specific heat
B. Latent heat of vaporisation
C. Viscosity
D. Specific vapor volume
Answer : C

22. The unit of fugacity is the same as that of the
A. Pressure
B. Temperature
C. Volume
D. Molar concentration
Answer : A

23. 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

24. 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

25. Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the
A. Two temperatures only
B. Pressure of working fluid
C. Mass of the working fluid
D. Mass and pressure both of the working fluid
Answer : A

26. The standard state of a gas (at a given temperature) is the state in which fugacity is equal to
A. Unity
B. Activity
C. Both (A) & (B)
D. Neither (A) nor (B)
Answer : C

27. The principle applied in liquefaction of gases is
A. Adiabatic expansion
B. Joule-Thomson effect
C. Both (A) and (B)
D. Neither (A) nor (B)
Answer : C

28. Which of the following is not affected by temperature changes?
A. Fugacity
B. Activity co-efficient
C. Free energy
D. None of these
Answer : D

29. The equilibrium constant for a chemical reaction at two different temperatures is given by
A. Kp₂/Kp₁ = - (?H/R) (1/T₂ - 1/T₁)
B. Kp₂/Kp₁ = (?H/R) (1/T₂ - 1/T₁)
C. Kp₂/Kp₁ = ?H (1/T₂ - 1/T₁)
D. Kp₂/Kp₁ = - (1/R) (1/T₂ - 1/T₁)
Answer : A

30. The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same.
A. Kinematic viscosity
B. Work
C. Temperature
D. None of these
Answer : D

31. When a gas in a vessel expands, its internal energy decreases. The process involved is
A. Reversible
B. Irreversible
C. Isothermal
D. Adiabatic
Answer : A

32. Compressibility factor of a gas is
A. Not a function of its pressure
B. Not a function of its nature
C. Not a function of its temperature
D. Unity, if it follows PV = nRT
Answer : A

33. PV^y = constant, holds good for an isentropic process, which is
A. Reversible and isothermal
B. Isothermal and irreversible
C. Reversible and adiabatic
D. Adiabatic and irreversible
Answer : C

34. Efficiency of a Carnot engine working between temperatures T₁ and T₂ (T₁ < T) is
A. (T₂ - T₁)/T₂
B. (T₂ - T₁)/T₁
C. (T₁ - T₂)/T₂
D. (T₁ - T₂)/T₁
Answer : A

35. The internal energy of an ideal gas does not change in a reversible __________ process.
A. Isothermal
B. Adiabatic
C. Isobaric
D. Isometric
Answer : A

36. A refrigeration cycle is a reversed heat engine. Which of the following has the maximum value of the co-efficient of performance (COP) for a given refrigeration effect?
A. Vapor compression cycle using expansion valve
B. Air refrigeration cycle
C. Vapor compression cycle using expansion engine
D. Carnot refrigeration cycle
Answer : D

37. Which of the following decreases with increase in pressure?
A. Melting point of ice
B. Melting point of wax
C. Boiling point of liquids
D. None of these
Answer : A

38. On a P-V diagram of an ideal gas, suppose a reversible adiabatic line intersects a reversible isothermal line at point A. Then at a point A, the slope of the reversible adiabatic line (?P/?V)_s and the slope of the reversible isothermal line (?P/ ?V)_T are related as (where, y = C_p/C_v)
A. (?P/?V)_S = (?P/?V)_T
B. (?P/?V)_S = [(?P/?V)_T]^Y
C. (?P/?V)_S = y(?P/?V)_T
D. (?P/?V)_S = 1/y(?P/?V)_T
Answer : C

39. Free energy
A. Decreases in all spontaneous (or irreversible) processes
B. Change during a spontaneous process has a negative value
C. Remains unchanged in reversible processes carried at constant temperature and pressure
D. All (A), (B) and (C)
Answer : D

40. As the temperature is lowered towards the absolute zero, the value of the quantity (??F/?T) approaches
A. Zero
B. Unity
C. Infinity
D. None of these
Answer : A

41. For an exothermic reaction
A. Only enthalpy change (?H) is negative
B. Only internal energy change (?E) is negative
C. Both ?H and ?E are negative
D. Enthalpy change is zero
Answer : C

42. For an ideal gas, the internal energy depends upon its __________ only.
A. Molecular size
B. Temperature
C. Volume
D. Pressure
Answer : B

43. For a spontaneous process, free energy
A. Is zero
B. Increases
C. Decreases whereas the entropy increases
D. And entropy both decrease
Answer : C

44. If the internal energy of an ideal gas decreases by the same amount as the work done by the system, then the
A. Process must be isobaric
B. Temperature must decrease
C. Process must be adiabatic
D. Both (B) and (C)
Answer : D

45. C_p of a gas at its critical temperature and pressure
A. Becomes zero
B. Becomes infinity
C. Equals 1 kcal/kmol °K
D. Equals 0.24 kcal/kmol °K
Answer : B

46. The ammonia synthesis reaction represented by N₂ + 3H₂ ? 2NH₃; ?H = - 22.4 kcal, is
A. Endothermic
B. Exothermic
C. Isothermal
D. Adiabatic
Answer : B

47. After throttling, gas temperature
A. Decreases
B. Increases
C. Remain same
D. May increase or decrease; depends on the nature of the gas
Answer : A

48. Grams of butane (C₄H₁₀) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
A. 580
B. 640
C. 1160
D. Data insufficient; can't be computed
Answer : C

49. In an irreversible process
A. Tds = dE - dW = 0
B. dE - dW - Tds = 0
C. Tds - dE + dW < 0
D. Tds - dT + dW < 0
Answer : C

50. Fundamental principle of refrigeration is based on the __________ law of thermodynamics.
A. Zeroth
B. First
C. Second
D. Third
Answer : C