JEE Main - Second law of thermodynamics spontaneity and Gibbs free energy Online Test (MCQ Quiz)

1. Which of the following statements correctly defines spontaneity for a process?

A) A process that occurs only when external work is done on the system. B) A process that occurs without the need for continuous external intervention. C) A process that is reversible under all conditions. D) A process that always leads to an increase in the entropy of the surroundings.

2. The second law of thermodynamics states that for any spontaneous process:

A) The total energy of the universe decreases. B) The total entropy of the universe increases. C) The total entropy of the universe remains constant. D) The total enthalpy of the universe decreases.

3. Which thermodynamic quantity is defined as a measure of the disorder or randomness of a system?

A) Enthalpy B) Gibbs Free Energy C) Entropy D) Internal Energy

4. For an isolated system, a spontaneous process is characterized by:

A) ΔS_system > 0 B) ΔS_system < 0 C) ΔS_system = 0 D) ΔH_system < 0

5. What is the mathematical expression for the change in Gibbs free energy (ΔG) at constant temperature and pressure?

A) ΔG = ΔH - TΔS B) ΔG = ΔS - TΔH C) ΔG = TΔS - ΔH D) ΔG = ΔH + TΔS

6. A process is spontaneous at constant temperature and pressure if:

A) ΔG > 0 B) ΔG < 0 C) ΔG = 0 D) ΔH < 0

7. If ΔG = 0 for a process at constant temperature and pressure, the system is:

A) Non-spontaneous B) Spontaneous C) At equilibrium D) Exothermic

8. For a process to be spontaneous at constant temperature and pressure, the term TΔS must be:

A) Less than ΔH B) Greater than ΔH C) Equal to ΔH D) Less than ΔS

9. An exothermic process (ΔH < 0) is always spontaneous if:

A) ΔS < 0 B) ΔS = 0 C) ΔS > 0 D) TΔS < |ΔH|

10. An endothermic process (ΔH > 0) can be spontaneous if:

A) TΔS is sufficiently negative. B) TΔS is sufficiently large and positive. C) TΔS is equal to ΔH. D) TΔS is zero.

11. Which factor primarily determines the spontaneity of a process at constant temperature and pressure?

A) The change in enthalpy alone. B) The change in entropy alone. C) The change in internal energy alone. D) The combined effect of enthalpy and entropy changes.

12. The units of Gibbs free energy are typically:

A) Joules per Kelvin (J/K) B) Joules (J) C) Joules per mole (J/mol) D) Kilojoules per mole (kJ/mol)

13. The temperature at which a reversible phase transition occurs (e.g., melting, boiling) is characterized by:

A) ΔG > 0 B) ΔG < 0 C) ΔG = 0 D) ΔH = 0

14. Consider the reaction N2(g) + 3H2(g) <=> 2NH3(g). If this reaction is exothermic (ΔH < 0) and involves a decrease in the number of moles of gas, how does temperature affect its spontaneity?

A) Spontaneity increases with increasing temperature. B) Spontaneity decreases with increasing temperature. C) Spontaneity is independent of temperature. D) Spontaneity is only dependent on pressure.

15. If ΔH > 0 and ΔS < 0 for a process, it is:

A) Spontaneous at all temperatures. B) Non-spontaneous at all temperatures. C) Spontaneous at low temperatures only. D) Spontaneous at high temperatures only.

16. The entropy change (ΔS) for the expansion of an ideal gas into a vacuum is:

A) Zero B) Positive C) Negative D) Cannot be determined

17. The spontaneity of a process is a kinetic concept. True or False?

A) True B) False C) Depends on the process D) Partially true

18. What is the relationship between the change in Gibbs free energy (ΔG) and the equilibrium constant (K) for a reaction at temperature T?

A) ΔG° = -RT ln K B) ΔG° = RT ln K C) ΔG = -RT ln K D) ΔG = RT ln K

19. If ΔG° is negative, the equilibrium constant K will be:

A) Less than 1 B) Equal to 1 C) Greater than 1 D) Zero

20. The standard Gibbs free energy change (ΔG°) refers to conditions where:

A) Reactants and products are at equilibrium. B) Reactants are at 1 atm pressure and products are at 1 atm pressure. C) Reactants and products are in their standard states. D) Temperature is 0 K.

21. For a reversible reaction at equilibrium, the rate of the forward reaction is:

A) Greater than the rate of the reverse reaction. B) Less than the rate of the reverse reaction. C) Equal to the rate of the reverse reaction. D) Zero

22. Which of the following processes would have a significant increase in entropy?

A) Freezing of water B) Condensation of steam C) Dissolving salt in water D) Combustion of methane

23. The entropy of a perfectly crystalline solid at absolute zero (0 K) is theoretically:

A) Maximum B) Zero C) Infinity D) Undefined

24. When a liquid evaporates, the entropy change (ΔS) is:

A) Positive B) Negative C) Zero D) Depends on the liquid

25. Which statement best describes the relationship between enthalpy, entropy, and spontaneity at constant T and P?

A) A decrease in enthalpy and an increase in entropy both favor spontaneity. B) A decrease in enthalpy and a decrease in entropy both favor spontaneity. C) An increase in enthalpy and an increase in entropy both favor spontaneity. D) An increase in enthalpy and a decrease in entropy both favor spontaneity.

26. The Gibbs free energy is a state function. This means:

A) Its value depends on the path taken. B) Its value depends only on the initial and final states. C) It is always zero for a spontaneous process. D) It is always negative for a spontaneous process.

27. For a process occurring at constant volume and temperature, the spontaneity is determined by the change in:

A) Gibbs free energy B) Helmholtz free energy C) Enthalpy D) Entropy

28. The Helmholtz free energy (A) is defined as:

A) A = H - TS B) A = U - TS C) A = G - TS D) A = U + PV

29. A process is spontaneous at constant volume and temperature if:

A) ΔA > 0 B) ΔA < 0 C) ΔA = 0 D) ΔU < 0

30. The difference between Gibbs free energy (G) and Helmholtz free energy (A) is:

A) PV B) PV/T C) T/PV D) U

31. In the equation ΔG = ΔH - TΔS, the term TΔS represents:

A) The energy released by the system. B) The energy absorbed by the system. C) The energy available to do non-expansion work. D) The energy associated with the change in disorder.

32. Consider the dissolution of a solute in a solvent. If ΔH > 0 (endothermic) and the process is spontaneous, then it must be that:

A) ΔS is negative and large. B) ΔS is positive and large. C) ΔS is zero. D) ΔH is equal to TΔS.

33. The second law of thermodynamics is often called the law of:

A) Conservation of Energy B) Conservation of Mass C) Increasing Entropy D) Conservation of Momentum

34. For a process to be irreversible, the total entropy change of the universe (ΔS_universe) is:

A) ΔS_universe = 0 B) ΔS_universe < 0 C) ΔS_universe > 0 D) ΔS_universe = ΔS_system

35. Which of the following is NOT a state function?

A) Enthalpy B) Entropy C) Gibbs Free Energy D) Work

36. The spontaneity of a reaction is determined by the sign of ΔG. What does a positive ΔG indicate?

A) The reaction is spontaneous in the forward direction. B) The reaction is spontaneous in the reverse direction. C) The reaction is at equilibrium. D) The reaction is exothermic.

37. Which of the following is a measure of the maximum amount of work that can be extracted from a thermodynamic system at constant temperature and pressure?

A) Enthalpy (ΔH) B) Entropy (ΔS) C) Gibbs Free Energy (ΔG) D) Internal Energy (ΔU)

38. For the reaction A(g) <=> B(g), if ΔH is negative and ΔS is positive, the reaction is:

A) Spontaneous at all temperatures. B) Non-spontaneous at all temperatures. C) Spontaneous only at high temperatures. D) Spontaneous only at low temperatures.

39. The entropy of a system tends to increase when:

A) The system is cooled. B) The number of particles decreases. C) The system becomes more ordered. D) The number of possible microstates increases.

40. Which statement about the Gibbs free energy is correct?

A) It is a measure of the total energy of a system. B) It is a measure of the disorder of a system. C) It represents the energy available to do useful work. D) It is always positive for spontaneous processes.

41. In the context of the second law of thermodynamics, the 'universe' is defined as:

A) All of space and time. B) The system plus its surroundings. C) Only the system being studied. D) Only the surroundings of the system.

42. Consider the melting of ice at 25°C. This process is spontaneous. What can be said about ΔH and ΔS for this process?

A) ΔH > 0, ΔS > 0 B) ΔH < 0, ΔS < 0 C) ΔH > 0, ΔS < 0 D) ΔH < 0, ΔS > 0

43. The relationship ΔG = ΔH - TΔS is valid for processes occurring at:

A) Constant volume only. B) Constant pressure only. C) Constant temperature only. D) Constant temperature and pressure.

44. If a reaction has a very large positive equilibrium constant (K >> 1), then the standard Gibbs free energy change (ΔG°) will be:

A) Large and positive. B) Large and negative. C) Close to zero. D) Equal to zero.

45. Which of the following is a consequence of the second law of thermodynamics?

A) Energy can be created but not destroyed. B) The total entropy of an isolated system never decreases. C) The enthalpy of the universe is constant. D) All processes are reversible.

46. For a reversible adiabatic process, the change in entropy of the universe is:

A) Positive B) Negative C) Zero D) Cannot be determined

47. What is the term 'TΔS' in the Gibbs free energy equation related to?

A) The change in internal energy. B) The energy that is unavailable to do useful work due to disorder. C) The total energy change of the system. D) The change in enthalpy.

48. If a process is spontaneous, the entropy of the universe must:

A) Increase B) Decrease C) Remain constant D) Be zero

49. The Gibbs free energy change for a reaction at non-standard conditions can be calculated using the equation:

A) ΔG = ΔH° - TΔS° B) ΔG° = -RT ln K C) ΔG = ΔG° + RT ln Q D) ΔG = TΔS - ΔH

50. A process that is spontaneous at a given temperature and pressure will have a Gibbs free energy change (ΔG) that is:

A) Positive B) Negative C) Zero D) Dependent on the enthalpy change only.

Second law of thermodynamics spontaneity and Gibbs free energy - Online Test

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