CAT - Chemical Engineering Thermodynamics 1000+ MCQ [Solved] PDF Download

1. The rate at which a substance reacts is proportional to its active mass and the rate of a chemical reaction is proportional to the product of active masses of the reacting substances. This is the
A. Lewis-Randall rule
B. Statement of Van't Hoff Equation
C. Le-Chatelier's principle
D. None of these
Answer : D

2. Dry ice is
A. Moisture free ice
B. Solid helium
C. Solid carbon dioxide
D. None of these
Answer : C

3. 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

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

5. __________ calorimeter is normally used for measuring the dryness fraction of steam, when it is very low.
A. Bucket
B. Throttling
C. Separating
D. A combination of separating & throttling
Answer : D

6. 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

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

8. 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

9. 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

10. 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

11. 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

12. Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.).
A. Entropy
B. Internal energy
C. Enthalpy
D. Gibbs free energy
Answer : D

13. An ideal liquid refrigerant should
A. Not have a sub-atmospheric vapour pressure at the temperature in the refrigerator coils
B. Not have unduly high vapour pressure at the condenser temperature
C. Both (A) and (B)
D. Have low specific heat
Answer : C

14. Consider the reaction, C + O₂ ? CO₂; ?H = - 94 kcal. What will be the value of ?H for the reaction CO₂ ? C + O₂?
A. -94 kcal
B. +94 kcal
C. > 94 kcal
D. < -94 kcal
Answer : B

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

16. 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

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

18. Critical solution temperature (or the consolute temperature) for partially miscible liquids (e.g., phenol-water) is the minimum temperature at which
A. A homogeneous solution (say of phenol water) is formed
B. Mutual solubility of the two liquids shows a decreasing trend
C. Two liquids are completely separated into two layers
D. None of these
Answer : A

19. Out of the following refrigeration cycles, which one has maximum COP?
A. Air cycle
B. Carnot cycle
C. Ordinary vapor compression cycle
D. Vapor compression with a reversible expansion engine
Answer : B

20. 4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is
A. 4 J
B. ?
C. 0
D. 8 J
Answer : C

21. 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

22. At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole.
A. 72
B. 92
C. 142
D. 192
Answer : B

23. Melting of ice exemplifies a/an
A. Adiabatic process
B. Endothermic reaction
C. Exothermic reaction
D. Process involving a chemical reaction
Answer : B

24. Which of the following non-flow reversible compression processes require maximum work?
A. Adiabatic process
B. Isothermal process
C. Isobaric process
D. All require same work
Answer : A

25. Boiling of liquid is accompanied with increase in the
A. Vapor pressure
B. Specific Gibbs free energy
C. Specific entropy
D. All (A), (B) and (C)
Answer : A

26. What is the value of maximum COP in case of absorption refrigeration, if refrigeration provided is at temperature, T_R (where, T₁ and T₂ are source & surrounding temperatures respectively.)?
A. T_R/(T₂ - T_R) × (T₁ - T₂)/T₁
B. T_R/(T₂ - T_R) × T₁/(T₁ - T₂)
C. T_R/(T₁ - T_R) × (T₁ - T₂)/T₁
D. None of these
Answer : A

27. 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

28. Which one is true for a throttling process?
A. A gas may have more than one inversion temperatures
B. The inversion temperature is different for different gases
C. The inversion temperature is same for all gases
D. The inversion temperature is the temperature at which Joule-Thomson co-efficient is infinity
Answer : B

29. When dilute aqueous solutions of two salts are mixed, the process is associated with
A. Decrease in temperature
B. Increase in temperature
C. No change in temperature
D. Change in temperature which is a function of composition
Answer : B

30. PV? = Constant (where, ? = Cp/Cv) is valid for a/an __________ process.
A. Isothermal
B. Isentropic
C. Isobaric
D. Adiabatic
Answer : D

31. Specific/molar Gibbs free energy for a pure substance does not change during
A. Sublimation
B. Vaporisation
C. Melting
D. Either (A), (B) or (C)
Answer : D

32. 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

33. 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

34. There is a change in __________ during the phase transition.
A. Volume
B. Pressure
C. Temperature
D. All a, b & c
Answer : A

35. Choose the condition that must be specified in order to liquify CO₂ (triple point for CO₂ is - 57°C and 5.2 atm).
A. Pressure must be kept below 5.2 atm
B. Temperature must be kept above - 57°C
C. Pressure must be kept below 5.2 atm. and temperature must be kept above 57°C
D. Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively
Answer : D

36. A gas shows deviation from ideal behaviour at
A. Low pressure and high temperature
B. Low pressure and low temperature
C. Low temperature and high pressure
D. High temperature and high pressure
Answer : C

37. __________ Equation predicts the activity coefficient from experimental data.
A. Lewis-Randall
B. Margules
C. Van Laar
D. Both (B) & (C)
Answer : D

38. 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

39. In an ideal refrigeration cycle, the change in internal energy of the fluid is
A. +ve
B. -ve
C. 0
D. Either of the above three; depends on the nature of refrigerant
Answer : C

40. Entropy of a substance remains constant during a/an __________ change.
A. Reversible isothermal
B. Irreversible isothermal
C. Reversible adiabatic
D. None of these
Answer : C

41. What happens in a reversible adiabatic expansion process?
A. Heating takes place
B. Cooling takes place
C. Pressure is constant
D. Temperature is constant
Answer : B

42. Sublimation temperature of dry ice (solid CO₂) is __________ °C.
A. -273
B. 0
C. -78
D. 5
Answer : C

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

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. 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

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

47. Steam undergoes isentropic expansion in a turbine from 5000 kPa and 400°C (entropy = 6.65 kJ/kg K) to 150 kPa) (entropy of saturated liquid = 1.4336 kJ/kg. K, entropy of saturated vapour = 7.2234 kJ/kg. K) The exit condition of steam is
A. Superheated vapour
B. Partially condensed vapour with quality of 0.9
C. Saturated vapour
D. Partially condensed vapour with quality of 0.1
Answer : A

48. Mollier diagram is a plot of
A. Temperature vs. enthalpy
B. Temperature vs. enthalpy
C. Entropy vs. enthalpy
D. Temperature vs. internal energy
Answer : C

49. Rotary lime kiln is an example of a/an __________ system.
A. Closed
B. Open
C. Isolated
D. Non-thermodynamic
Answer : B

50. For an isothermal process, the internal energy of a gas
A. Increases
B. Decreases
C. Remains unchanged
D. Data insufficient, can't be predicted
Answer : C