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

1. The activity of an ideal gas is numerically __________ its pressure.
A. More than
B. Less than
C. Equal to
D. Data insufficient, can't be predicted
Answer : C

2. Internal energy is equal to the heat absorbed in case of a/an __________ process.
A. Constant volume
B. Polytropic
C. Adiabatic
D. Constant pressure
Answer : A

3. A large iceberg melts at the base, but not at the top, because of the reason that
A. Ice at the base contains impurities which lowers its melting point
B. Due to the high pressure at the base, its melting point reduces
C. The iceberg remains in a warmer condition at the base
D. All (A), (B) and (C)
Answer : B

4. Heat of formation of an element in its standard state is
A. 0
B. < 0
C. > 0
D. A function of pressure
Answer : A

5. Henry's law is closely obeyed by a gas, when its __________ is extremely high.
A. Pressure
B. Solubility
C. Temperature
D. None of these
Answer : D

6. 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

7. A refrigerator works on the principle of __________ law of thermodynamics.
A. Zeroth
B. First
C. Second
D. Third
Answer : C

8. 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

9. (?T/?P)H is the mathematical expression for
A. Specific heat at constant pressure (C_p)
B. Specific heat at constant volume (C_v)
C. Joule-Thompson co-efficient
D. None of these
Answer : C

10. The expression for entropy change given by, ?S = - nR ln (P₂/P₁), holds good for
A. Expansion of a real gas
B. Reversible isothermal volume change
C. Heating of an ideal gas
D. Cooling of a real gas
Answer : B

11. 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

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

13. The work done in isothermal compression compared to that in adiabatic compression will be
A. Less
B. More
C. Same
D. More or less depending upon the extent of work done
Answer : B

14. Pick out the extensive property out of the following.
A. Surface tension
B. Free energy
C. Specific heat
D. Refractive index
Answer : B

15. A two stage compressor is used to compress an ideal gas. The gas is cooled to the initial temperature after each stage. The intermediate pressure for the minimum total work requirement should be equal to the __________ mean of P₁ and P₂. (where, P₁ and P₂ are initial and final pressures respectively)
A. Logarithmic
B. Arithmetic
C. Geometric
D. Harmonic
Answer : C

16. Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in
A. Increased COP
B. Same COP
C. Decreased COP
D. Increased or decreased COP; depending upon the type of refrigerant
Answer : A

17. With increase in compression ratio, the efficiency of the otto engine
A. Increases
B. Decreases
C. Remain constant
D. Increases linearly
Answer : A

18. The freezing point of a liquid decreases when the pressure is increased, if the liquid __________ while freezing.
A. Contracts
B. Expands
C. Does not change in volume
D. Either (A), (B) or (C)
Answer : A

19. Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?
A. Freon
B. Liquid sulphur dioxide
C. Methyl chloride
D. Ammonia
Answer : A

20. 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

21. 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

22. Degree of freedom of the system ice-watervapour will be
A. 0
B. 1
C. 2
D. 3
Answer : A

23. 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

24. In the reaction, C + O₂ ? CO₂; ?H = - 94 kcal. What is the heat content (enthalpy) of O₂?
A. -94 kcal
B. > -94 kcal
C. < - 94 kcal
D. Zero
Answer : D

25. Pick out the correct statement.
A. A real gas on expansion in vacuum gets heated up
B. An ideal gas on expansion in vacuum gets cooled
C. An ideal gas on expansion in vacuum gets heated up
D. A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected
Answer : D

26. In Joule-Thomson porous plug experiment, the
A. Enthalpy does not remain constant
B. Entire apparatus is exposed to surroundings
C. Temperature remains constant
D. None of these
Answer : D

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

28. Pick out the wrong statement.
A. A closed system does not permit exchange of mass with its surroundings but may permit exchange of energy.
B. An open system permits exchange of both mass and energy with its surroundings
C. The term microstate is used to characterise an individual, whereas macro-state is used to designate a group of micro-states with common characteristics
D. None of the above
Answer : D

29. The extensive properties are
A. Volume, mass and number of moles
B. Free energy, entropy and enthalpy
C. Both (A) and (B)
D. None of these
Answer : C

30. Pick out the wrong statement.
A. The net change in entropy in any reversible cycle is always zero
B. The entropy of the system as a whole in an irreversible process increases
C. The entropy of the universe tends to a maximum
D. The entropy of a substance does not remain constant during a reversible adiabatic change
Answer : D

31. The chemical potential of any constituent of an ideal solution depends on the __________ of the solution.
A. Temperature
B. Pressure
C. Composition
D. All (A), (B) and (C)
Answer : D

32. 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

33. Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.
A. Reaction mechanism
B. Calculation of rates
C. Energy transformation from one form to another
D. None of these
Answer : C

34. Enthalpy changes over a constant pressure path are always zero for __________ gas.
A. Any
B. A perfect
C. An easily liquefiable
D. A real
Answer : B

35. Out of the following refrigeration cycles, which one has the minimum COP (Co-efficient of performance)?
A. Air cycle
B. Carnot cycle
C. Ordinary vapour compression cycle
D. Vapour compression with a reversible expansion engine
Answer : A

36. COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
A. 0.5
B. 3.5
C. 4.5
D. 8.5
Answer : B

37. When a gas is expanded from high pressure region to low pressure region; temperature change occurs. This phenomenon is related to the
A. Gibbs-Duhem equation
B. Gibbs-Helmholtz equation
C. Third law of thermodynamics
D. Joule-Thomson effect
Answer : D

38. For a constant pressure reversible process, the enthalpy change (?H) of the system is
A. C_v.dT
B. C_p.dT
C. ? C_p.dT
D. ? C_v.dT
Answer : C

39. Which is not a refrigerant?
A. SO₂
B. NH₃
C. CCl₂F₂
D. C₂H₄Cl₂
Answer : D

40. Fugacity co-efficient of a substance is the ratio of its fugacity to
A. Mole fraction
B. Activity
C. Pressure
D. Activity co-efficient
Answer : C

41. Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is
A. 1
B. 2
C. 3
D. 4
Answer : B

42. With increase in pressure (above atmospheric pressure), the C_p of a gas
A. Increases
B. Decreases
C. Remains unchanged
D. First decreases and then increases
Answer : A

43. The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are
A. Zero
B. One
C. Two
D. Three
Answer : B

44. What is the value of ln y (where y = activity co-efficient) for ideal gases?
A. Zero
B. Unity
C. Infinity
D. Negative
Answer : A

45. For an ideal gas, the chemical potential is given by
A. RT d ln P
B. R d ln P
C. R d ln f
D. None of these
Answer : A

46. An isentropic process is carried out at constant
A. Volume
B. Pressure
C. Temperature
D. All (A), (B) and (C)
Answer : A

47. 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

48. The equation, C_p - C_v = R, is true for __________ gas.
A. No
B. Any real
C. Only ideal
D. Both (B) and (C)
Answer : C

49. If heat contents of CH₄, C₂H₄ and C₃H₈ are -17.9, 12.5 and -24.8 kcal/mole respectively, than ?H for the reaction CH₄(g) + C₂H₄(g) ? C₃H₈(g) will be __________ Kcal.
A. -19.4
B. -30.2
C. 55.2
D. -55.2
Answer : A

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