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

1. 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

2. Refrigeration cycle
A. Violates second law of thermodynamics
B. Involves transfer of heat from low temperature to high temperature
C. Both (A) and (B)
D. Neither (A) nor (B)
Answer : B

3. 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

4. Which of the following identities can be most easily used to verify steam table data for superheated steam?
A. (?T/?V)_S = (?p/?S)_V
B. (?T/?P)_S = (?V/?S)_P
C. (?P/?T)_V = (?S/?V)_T
D. (?V/?T)_P = -(?S/?P)_T
Answer : D

5. Activity co-efficient is a measure of the
A. Departure from ideal solution behaviour
B. Departure of gas phase from ideal gas law
C. Vapour pressure of liquid
D. None of these
Answer : A

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

7. A system undergoes a change from a given initial state to a given final state either by an irreversible process or by a reversible process, then (where, ? S₁ and ? S_R are the entropy changes of the system for the irreversible and reversible processes respectively)
A. ? S₁ is always < ? S_R
B. ? S₁ is sometimes > ? S_R
C. ? S₁ is always > ? S_R
D. ? S₁ is always = ? S_R
Answer : C

8. The free energy change for a chemical reaction is given by (where, K = equilibrium constant)
A. RT ln K
B. -RT ln K
C. -R ln K
D. T ln K
Answer : B

9. 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

10. __________ law of thermodynamics ascertains the direction of a particular spontaneous process.
A. Zeroth
B. First
C. Second
D. Third
Answer : C

11. Entropy of an ideal gas depends upon its
A. Pressure
B. Temperature
C. Both (A) & (B)
D. Neither (A) nor (B)
Answer : C

12. 1m3 of an ideal gas at 500 K and 1000 kPa expands reversibly to 5 times its initial volume in an insulated container. If the specific heat capacity (at constant pressure) of the gas is 21 J/mole . K, the final temperature will be
A. 35 K
B. 174 K
C. 274 K
D. 154 K
Answer : C

13. Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process.
A. Equilibrium
B. Adiabatic
C. Steady
D. Unsteady
Answer : D

14. The necessary and sufficient condition for equilibrium between two phases is
A. The concentration of each component should be same in the two phases
B. The temperature of each phase should be same
C. The pressure should be same in the two phases
D. The chemical potential of each component should be same in the two phases
Answer : D

15. Specific volume of an ideal gas is
A. Equal to its density
B. The reciprocal of its density
C. Proportional to pressure
D. None of these
Answer : B

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

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

18. 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

19. Chemical potential (an intensive property) of a substance is a force that drives the chemical system to equilibrium and is equal to its partial molar properties. The ratio of chemical potential to free energy of a pure substance at constant temperature and pressure is
A. 0
B. 1
C. ?
D. None of these
Answer : B

20. Those solutions in which there is no volume change upon mixing the components in the liquid state and which, when diluted do not undergo any heat change (i.e. heat of dilution is zero), are called __________ solutions.
A. Ideal
B. Real
C. Isotonic
D. None of these
Answer : A

21. 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

22. A gas performs the maximum work, when it expands
A. Non-uniformly
B. Adiabatically
C. Isobarically
D. Isothermally
Answer : C

23. The work done in an adiabatic change in a particular gas depends upon changes in the __________ only.
A. Temperature
B. Specific heat
C. Volume
D. Pressure
Answer : A

24. 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

25. Entropy, which is a measure of the disorder of a system, is:
A. Independent of pressure
B. Independent of temperature
C. Zero at absolute zero temperature for a perfect crystalline substance
D. All (A), (B) & (C)
Answer : C

26. The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise.
A. Increases
B. Decreases
C. Remains unchanged
D. Decreases linearly
Answer : A

27. Which of the following is Virial equation of state?
A. (p + a/V²)(V - b) = nRT
B. PV = nRT
C. PV = A + B/V + C/V² + D/V³ + ...
D. None of these
Answer : C

28. Heat requirement for decomposition of a compound into its elements is __________ that is evolved during the formation of that compound from its elements.
A. The same
B. Less than
C. Greater than
D. Different than
Answer : A

29. Boyle's law for gases states that
A. P ? 1/V, when temperature is constant
B. P ? 1/V, when temperature & mass of the gas remain constant
C. P ? V, at constant temperature & mass of the gas
D. P/V = constant, for any gas
Answer : B

30. 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

31. Clausius-Clapeyron Equation gives accurate result, when the
A. Vapour pressure is relatively low and the temperature does not vary over wide limits
B. Vapour obeys the ideal gas law and the latent heat of vaporisation is constant
C. Volume in the liquid state is negligible compared with that in the vapour state
D. All (A), (B) and (C)
Answer : D

32. During a reversible isothermal expansion of an ideal gas, the entropy change is
A. +ve
B. 0
C. -ve
D. ?
Answer : A

33. Which of the following represents the Virial equation of state?
A. T = [RT/(V- b)] - [a/?T. V(V + b)]
B. PV/RT = 1 + (B/V) + (C/V²) + ……
C. n₁u₂ + ?₂?₁ = 0
D. None of these
Answer : B

34. At __________ point, all the three phases (i.e. solid, liquid and gas) co-exist.
A. Eutectic
B. Triple
C. Plait
D. Critical
Answer : B

35. The chemical potential of a component (?i) of a phase is the amount by which its capacity for doing all work, barring work of expansion is increased per unit amount of substance added for an infinitesimal addition at constant temperature and pressure. It is given by
A. (?E/?n_i)_{S, v, nj}
B. (?G/?n_i)_{T, P, nj} = (?A/?ni) _{T, v, nj}
C. (?H/?n_i)_{S, P, nj}
D. All (A), (B) and (C)
Answer : D

36. 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

37. The internal energy of an ideal gas is a function of its __________ only.
A. Molecular size
B. Volume
C. Pressure
D. Temperature
Answer : D

38. Gibbs-Duhem equation
A. States that n₁d?₁ + n₂d?₂ + ....n_jd?_j = 0, for a system of definite composition at constant temperature and pressure
B. Applies only to binary systems
C. Finds no application in gas-liquid equilibria involved in distillation
D. None of these
Answer : A

39. 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

40. The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.
A. Lowest
B. Highest
C. Average
D. None of these
Answer : A

41. An isolated system can exchange __________ with its surroundings.
A. Matter
B. Energy
C. Neither matter nor energy
D. Both matter and energy
Answer : C

42. Work done in an adiabatic process between two states depends on the
A. Rate of heat transmission
B. Initial state only
C. End states only
D. None of these
Answer : C

43. If different processes are used to bring about the same chemical reaction, the enthalpy change is same for all of them. This is __________ law.
A. Hess's
B. Kirchoff's
C. Lavoisier and Laplace
D. None of these
Answer : A

44. Work done is a
A. Property of the system
B. Path function
C. Point function
D. State description of a system
Answer : B

45. A reasonably general expression for vapourliquid phase equilibrium at low to moderate pressure is ?_i y_i P = Y_i x_if_i° where, ? is a vapor fugacity component, Y_i is the liquid activity co-efficient and f_i° is the fugacity of the pure component i. the K_i value (Y_i = K_i x_i) is therefore, in general a function of
A. Temperature only
B. Temperature and pressure only
C. Temperature, pressure and liquid composition x_i only
D. Temperature, pressure, liquid composition x_i and vapour composition yi
Answer : C

46. The thermodynamic law, PV^y = constant, is not applicable in case of
A. Ideal compression of air
B. Free expansion of an ideal gas
C. Adiabatic expansion of steam in a turbine
D. Adiabatic compression of a perfect gas
Answer : B

47. Pick out the correct statement:
A. In an isothermal system, irreversible work is more than reversible work
B. Under reversible conditions, the adiabatic work is less than isothermal work
C. Heat, work, enthalpy and entropy are all 'state functions'
D. Matter and energy cannot be exchanged with the surroundings in a closed system
Answer : B

48. 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

49. Which of the following is not a unit of the equilibrium constant K_p? (where, ?x = number of moles of products number of moles of reactants)
A. (atm)^?x, when ?x is negative
B. (atm)^?x, when ?x is positive
C. Dimensionless, when ?x = 0
D. (atm)^?x2, when ?x > 0
Answer : D

50. The necessary condition for phase equilibrium in a multiphase system of N components is that the
A. Chemical potentials of a given component should be equal in all phases
B. Chemical potentials of all components should be same in a particular phase
C. Sum of the chemical potentials of any given component in all the phases should be the same
D. None of these
Answer : A