Chemical Engineering Thermodynamics MCQ Solved Paper for XAT

1. Which of the following is a thermodynamic property of a system?
A. Concentration
B. Mass
C. Temperature
D. Entropy
Answer : D

2. 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

3. Pick out the correct statement.
A. Compression ratio of an Otto engine is comparatively higher than a diesel engine
B. Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio
C. Otto engine efficiency decreases with the rise in compression ratio, due to decrease in work produced per quantity of heat
D. Diesel engine normally operates at lower compression ratio than an Otto engine for an equal output of work
Answer : B

4. For organic compounds, group contribution method can be used for the estimation of
A. Critical properties
B. Specific gravity
C. Specific volume
D. Thermal conductivity
Answer : A

5. 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

6. In an ideal gas mixture, fugacity of a species is equal to its
A. Vapor pressure
B. Partial pressure
C. Chemical potential
D. None of these
Answer : B

7. 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

8. A solute distributes itself between two nonmiscible solvents in contact with each other in such a way that, at a constant temperature, the ratio of its concentrations in two layers is constant, irrespective of its total amount. This is
A. The distribution law
B. Followed from Margules equation
C. A corollary of Henry's law
D. None of these
Answer : A

9. The internal energy of a gas obeying P (V - b) RT (where, b is a positive constant and has a constant C_v), depends upon its
A. Pressure
B. Volume
C. Temperature
D. All (A), (B) & (C)
Answer : C

10. 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

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

12. Which of the following is an undesirable characteristic of a refrigerant?
A. It should be non-explosive
B. It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils
C. Its vapor pressure at the condenser temperature should be very high
D. None of these
Answer : B

13. A solid is transformed into vapour without going to the liquid phase at
A. Triple point
B. Boiling point
C. Below triple point
D. Always
Answer : A

14. Third law of thermodynamics is helpful in
A. Prediction of the extent of a chemical reaction
B. Calculating absolute entropies of substances at different temperature
C. Evaluating entropy changes of chemical reaction
D. Both (B) and (C)
Answer : D

15. 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

16. __________ decreases during adiabatic throttling of a perfect gas.
A. Entropy
B. Temperature
C. Enthalpy
D. Pressure
Answer : D

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

18. 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

19. Which of the following equations is obtained on combining 1st and 2nd law of thermodynamics, for a system of constant mass?
A. dE = Tds - PdV
B. dQ = C_vdT + PdV
C. dQ = C_pdT + Vdp
D. Tds = dE - PdV
Answer : A

20. The molar excess Gibbs free energy, g^E, for a binary liquid mixture at T and P is given by, (g^E/RT) = A . x₁. x₂, where A is a constant. The corresponding equation for ln y₁, where y₁ is the activity co-efficient of component 1, is
A. A . x₂²
B. Ax₁
C. Ax₂
D. Ax₁²
Answer : A

21. The first law of thermodynamics is a restatement of the law of conservation of
A. Mass
B. Energy
C. Momentum
D. None of these
Answer : B

22. Which of the following is not a common refrigerant?
A. Freon-12
B. Ethylene
C. Ammonia
D. Carbon dioxide
Answer : B

23. The heat capacities for the ideal gas state depend upon the
A. Pressure
B. Temperature
C. Both (A) & (B)
D. Neither (A) nor (B)
Answer : B

24. Work done in case of free expansion is
A. Indeterminate
B. Zero
C. Negative
D. None of these
Answer : B

25. Melting of wax is accompanied with __________ in entropy.
A. Increase
B. Decrease
C. No change
D. None of these
Answer : A

26. Degrees of freedom at triple point will be
A. 0
B. 1
C. 2
D. 3
Answer : A

27. To obtain integrated form of Clausius-Clapeyron equation, ln (P₂/P₁) = (?H_V/R) (1/T₁ - 1/T₂) from the exact Clapeyron equation, it is assumed that the
A. Volume of the liquid phase is negligible compared to that of vapour phase
B. Vapour phase behaves as an ideal gas
C. Heat of vaporisation is independent of temperature
D. All (A), (B) & (C)
Answer : D

28. During Joule-Thomson expansion of gases
A. Enthalpy remains constant
B. Entropy remains constant
C. Temperature remains constant
D. None of these
Answer : A

29. 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

30. Heating of water under atmospheric pressure is an __________ process.
A. Isochoric
B. Isobaric
C. Adiabatic
D. Isothermal
Answer : B

31. The ratio of equilibrium constants (Kp2/Kp1) at two different temperatures is given by
A. (R/?H) (1/T₁ - 1/T₂)
B. (?H/R) (1/T₁ - 1/T₂)
C. (?H/R) (1/T₂ - 1/T₁)
D. (1/R) (1/T₁ - 1/T₂)
Answer : B

32. Trouton's ratio is given by (where ?b, = molal heat of vaporisation of a substance at its normal boiling point, kcal/kmol Tb = normal boiling point, °K)
A. ?b/Tb
B. Tb/?b
C. ?(?b/Tb)
D. ?(Tb/?b)
Answer : A

33. For an incompressible fluid, the __________ is a function of both pressure as well as temperature.
A. Internal energy
B. Enthalpy
C. Entropy
D. All (A), (B) & (C)
Answer : B

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

35. Pick out the wrong statement
A. Phase rule variables are intensive properties
B. Heat and work are both state function
C. The work done by expansion of a gas in vacuum is zero
D. C_P and C_V are state function
Answer : B

36. 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

37. 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

38. 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

39. It is desired to bring about a certain change in the state of a system by performing work on the system under adiabatic conditions.
A. The amount of work needed is path dependent
B. Work alone cannot bring out such a change of state
C. The amount of work needed is independent of path
D. More information is needed to conclude anything about the path dependence or otherwise of the work needed
Answer : A

40. High pressure steam is expanded adiabatically and reversibly through a well insulated turbine, which produces some shaft work. If the enthalpy change and entropy change across the turbine are represented by ?H and ?S respectively for this process:
A. ? H = 0 and ?S = 0
B. ? H ? 0 and ?S = 0
C. ? H ? 0 and ?S ? 0
D. ? H = 0 and ?S ? 0
Answer : B

41. During the phase transition, __________ changes.
A. Pressure
B. Volume
C. Temperature
D. All (A), (B) and (C)
Answer : B

42. Entropy change for an irreversible isolated system is
A. ?
B. 0
C. < 0
D. > 0
Answer : D

43. 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

44. The four properties of a system viz. P, V, T, S are related by __________ equation.
A. Gibbs-Duhem
B. Gibbs-Helmholtz
C. Maxwell's
D. None of these
Answer : C

45. For a given substance at a specified temperature, activity is __________ to fugacity.
A. Directly proportional
B. Inversely proportional
C. Equal
D. None of these
Answer : A

46. A cylinder contains 640 gm of liquid oxygen. The volume occupied (in litres) by the oxygen, when it is released and brought to standard conditions (0°C, 760 mm Hg) will be __________ litres.
A. 448
B. 224
C. 22.4
D. Data insufficient; can't be computed
Answer : A

47. The second law of thermodynamics states that
A. The energy change of a system undergoing any reversible process is zero
B. It is not possible to transfer heat from a lower temperature to a higher temperature
C. The total energy of system and surrounding remains the same
D. None of the above
Answer : D

48. First law of thermodynamics is mathematically stated as
A. dQ = dE + dW
B. dQ = dE - dW
C. dE = dQ + dW
D. dW = dQ + dE
Answer : A

49. A domestic refrigerator has a/an __________ cooled condenser.
A. Water
B. Air
C. Evaporative
D. Gas
Answer : B

50. Which of the following liquid metals has the highest thermal conductivity?
A. Molten sodium
B. Molten lead
C. Mercury
D. Molten potassium
Answer : A