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

1. Pick out the wrong statement.
A. A refrigeration cycle violates the second law of thermodynamics
B. Refrigeration cycle is normally represented by a temperature vs. entropy plot
C. In a refrigerator, work required decreases as the temperature of the refrigerator and the temperature at which heat is rejected increases
D. One ton of refrigeration is equivalent to the rate of heat absorption equal to 3.53 kW
Answer : A

2. Translational kinetic energy of molecules of an ideal gas is proportional to (where, T = absolute temperature of the gas)
A. T
B. ?T
C. T²
D. 1/?T
Answer : A

3. Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.
A. Isothermal
B. Adiabatic
C. Isentropic
D. None of these
Answer : A

4. The relation connecting the fugacities of various components in a solution with one another and to composition at constant temperature and pressure is called the __________ equation.
A. Gibbs-Duhem
B. Van Laar
C. Gibbs-Helmholtz
D. Margules
Answer : A

5. 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

6. 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

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

8. If two pure liquid constituents are mixed in any proportion to give an ideal solution, there is no change in
A. Volume
B. Enthalpy
C. Both (A) & (B)
D. Neither (A) nor (B)
Answer : C

9. The gas law (PV = RT) is true for an __________ change.
A. Isothermal
B. Adiabatic
C. Both (A) & (B)
D. Neither (A) nor (B)
Answer : C

10. The following heat engine produces power of 100,000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is
A. 100,000 kW
B. 160,000 kW
C. 200,000 kW
D. 320,000 kW
Answer : D

11. In a reversible process
A. Tds = dE + dW
B. dE - dW = Tds
C. dW - dE = Tds
D. Tds - dW + dE >0
Answer : A

12. 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

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

14. As the time is passing, entropy of the universe
A. Is increasing
B. Is decreasing
C. Remain constant
D. Data insufficient, can't be predicted
Answer : A

15. The root mean square speed of molecules of a gas is equal to (where, m = mass of the molecule K = Boltzmanns constant, T = absolute temperature)
A. ?(2KT/m)
B. ?(3KT/m)
C. ?(6KT/m)
D. 3KT/m
Answer : B

16. 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

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

18. The energy of activation of exothermic reaction is
A. Zero
B. Negative
C. Very large compared to that for endothermic reaction
D. Not possible to predict
Answer : D

19. Pick out the wrong statement.
A. The conversion for a gas phase reaction increases with decrease in pressure, if there is an increase in volume accompanying the reaction
B. With increase in temperature, the equilibrium constant increases for an exothermic reaction
C. The equilibrium constant of a reaction depends upon temperature only
D. The conversion for a gas phase reaction increases with increase in pressure, if there is a decrease in volume accompanying the reaction
Answer : B

20. When liquid and vapour phase of multi-component system are in equilibrium (at a given temperature and pressure), then chemical potential of each component is
A. Same in both the phases
B. Zero in both the phases
C. More in vapour phase
D. More in liqid phase
Answer : A

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

22. Internal energy of an element at 1 atm and 25° C is __________ kcal/kg.mole.
A. 0
B. 273
C. 25
D. None of these
Answer : A

23. In the reaction, H₂ +I₂ ? 2HI, addition of an inert gas will
A. Increase the partial pressure of H₂
B. Increase the partial pressure of I₂
C. Increase the total pressure and hence shift the equilibrium towards the right
D. Not affect the equilibrium conditions
Answer : D

24. 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

25. Which is not constant for an ideal gas?
A. (?P/?V)_T
B. (?V/?T)_P
C. (?P/?V)_V
D. All (A), (B) & (C)
Answer : A

26. Free energy change of mixing two liquid substances is a function of the
A. Concentration of the constituents only
B. Quantities of the constituents only
C. Temperature only
D. All (A), (B) and (C)
Answer : D

27. 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

28. At the critical point of a substance
A. The surface tension vanishes
B. Liquid and vapour have the same density
C. There is no distinction between liquid and vapour phases
D. All (A), (B) and (C)
Answer : D

29. Fugacity is most helpful in
A. Representing actual behaviour of real gases
B. Representing actual behaviour of ideal gases
C. The study of chemical equilibria involving gases at atmospheric pressure
D. None of these
Answer : A

30. For any system, what is the minimum number of degrees of freedom?
A. 0
B. 1
C. 2
D. 3
Answer : A

31. When a gas is subjected to adiabatic expansion, it gets cooled due to
A. Decrease in velocity
B. Decrease in temperature
C. Decrease in kinetic energy
D. Energy spent in doing work
Answer : D

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

33. 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

34. In a homogeneous solution, the activity coefficient of a component depends upon the
A. Pressure
B. Composition
C. Temperature
D. All (A), (B) and (C)
Answer : D

35. Standard temperature and pressure (S.T.P.) is
A. 0°C and 750 mm Hg
B. 15°C and 750 mm Hg
C. 0°C and 1 kgf/cm2
D. 15°C and 1 kgf/cm2
Answer : A

36. Gibbs free energy at constant pressure and temperature under equilibrium conditions is
A. ?
B. 0
C. Maximum
D. Minimum
Answer : D

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

38. 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

39. Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature.
A. Infinity
B. Minus infinity
C. Zero
D. None of these
Answer : B

40. If two gases have same reduced temperature and reduced pressure, then they will have the same
A. Volume
B. Mass
C. Critical temperature
D. None of these
Answer : D

41. 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

42. The efficiency of a Carnot heat engine operating between absolute temperatures T₁ and T₂ (when, T₁ > T₂) is given by (T₁ - T₂)/T1. The co-efficient of performance (C.O.P.) of a Carnot heat pump operating between T₁ and T₂ is given by
A. T₁/(T₁-T₂)
B. T₂/(T₁-T₂)
C. T₁/T₂
D. T₂/R₁
Answer : A

43. In the equation, PVⁿ = constant, if the value of n = 1, then it represents a reversible __________ process.
A. Isothermal
B. Isobaric
C. Polytropic
D. Adiabatic
Answer : A

44. Entropy is a measure of the __________ of a system.
A. Disorder
B. Orderly behaviour
C. Temperature changes only
D. None of these
Answer : A

45. Compound having large heat of formation is
A. More stable
B. Less stable
C. Not at all stable (like nascent O2)
D. Either more or less stable; depends on the compound
Answer : A

46. Chemical potential of ith component of a system is given by
A. ?_i = (?F/?n_i)_{T, P, ni}
B. ?_i = (?A/?n_i)_{T, P, ni}
C. ?_i = (?F/?n_i)_{T, P}
D. ?_i = (?A/?n_i)_{T, P}
Answer : A

47. For water at 300°C, it has a vapour pressure 8592.7 kPa and fugacity 6738.9 kPa Under these conditions, one mole of water in liquid phase has a volume of 25.28 cm3 and that in vapour phase in 391.1 cm3.Fugacity of water (in kPa) at 9000 kPa will be
A. 6738.9
B. 6753.5
C. 7058.3
D. 9000
Answer : B

48. Isotherm on an enthalpy-concentration diagram, for an ideal solution will be a
A. Straight line
B. Sine curve
C. Parabola
D. Hyperbola
Answer : A

49. Equation which relates pressure, volume and temperature of a gas is called the
A. Equation of state
B. Gibbs Duhem equation
C. Ideal gas equation
D. None of these
Answer : A

50. Which of the following is not correct for a reversible adiabatic process?
A. TV^?-1 = constant
B. p^1-?.T^Y = constant
C. PV^? = constant
D. None of these
Answer : D