Second law of thermodynamics and reversibility - One Line Questions

1. If a process is reversible, then the change in entropy of the universe is: — = 0
2. The mathematical expression for the Clausius inequality for any process is: — ∮ dQ/T ≤ 0
3. The maximum possible efficiency of a heat engine operating between two temperatures T_H (hot reservoir) and T_C (cold reservoir) is given by: — 1 - (T_C / T_H)
4. A heat engine operates between 500 K and 300 K. Its maximum possible efficiency is: — 40%
5. A refrigerator is a device that moves heat from a colder region to a hotter region. According to the Second Law, this process requires: — External work input.
6. Which of the following is an example of a process that increases the entropy of the universe? — The free expansion of a gas into a vacuum.
7. According to the Second Law of Thermodynamics, the entropy of an isolated system: — Always increases or remains constant
8. The change in entropy of a system during an irreversible process is: — Always greater than the heat added divided by temperature.
9. The total entropy change for a reversible process involving a system and its surroundings is: — Always zero
10. Friction in a mechanical system leads to an increase in: — Entropy
11. Which of the following is a direct consequence of the Second Law of Thermodynamics? — The universe tends towards maximum entropy
12. In any irreversible process, the entropy of the universe: — Increases
13. For a reversible process, the change in entropy is given by: — dS = dQ/T
14. Which of the following statements best describes the Second Law of Thermodynamics? — In any real process, the total entropy of an isolated system will always increase over time.
15. The Second Law of Thermodynamics is fundamentally about the directionality of processes and the concept of: — Entropy increase
16. Which of the following is a measure of the unavailability of energy to do work? — Entropy
17. Which of the following implies that it is impossible to achieve 100% efficiency in converting heat into work in a cyclic process? — Second Law of Thermodynamics
18. The second law of thermodynamics implies that: — It is impossible to transfer heat from a cold body to a hot body without external work.
19. Which statement best describes the relationship between entropy and irreversibility? — Irreversible processes always increase the total entropy of the universe.
20. Which of the following processes is irreversible? — Free expansion of a gas.
21. The Clausius statement of the Second Law of Thermodynamics states that: — It is impossible to construct a device which operates in a cycle and produces no effect other than the transfer of heat from a colder body to a hotter body.
22. The Kelvin-Planck statement of the Second Law of Thermodynamics states that: — It is impossible to construct a device which operates in a cycle and produces no effect other than the extraction of heat from a single reservoir and the performance of an equivalent amount of work.
23. A system is in thermodynamic equilibrium if: — Mechanical, thermal, and chemical equilibrium exist simultaneously.
24. Which of the following is a necessary condition for a process to be reversible? — The driving force must be infinitesimally larger than the opposing force.
25. A process is said to be reversible if: — It can be reversed by an infinitesimal change in a condition.
26. The term 'entropy' was introduced by: — Rudolf Clausius
27. Which of the following is NOT a statement of the Second Law of Thermodynamics? — Joule's law
28. In a reversible adiabatic process, the change in entropy is: — Zero
29. Carnot's theorem states that no engine operating between two heat reservoirs can be more efficient than a: — Carnot engine
30. The Carnot efficiency is the maximum theoretical efficiency for a heat engine operating between two temperatures. This maximum efficiency is achieved by a: — Hypothetical reversible engine
31. If a process occurs such that the entropy of the system decreases, but the entropy of the surroundings increases by a larger amount, the process is: — Irreversible and spontaneous
32. The process of mixing two different gases at the same temperature and pressure is: — Irreversible
33. The Carnot cycle is an example of a: — Reversible cycle
34. A process that can be reversed by an infinitesimal change in conditions is called: — Reversible
35. The efficiency of a real heat engine is always less than that of a Carnot engine operating between the same temperatures because: — Real processes are irreversible.
36. Which statement is true for a cyclic process? — The change in internal energy is always zero.
37. The concept of entropy is most closely associated with: — The degree of disorder or randomness in a system
38. Which of the following phenomena is a direct manifestation of the Second Law of Thermodynamics? — The flow of heat from a hotter body to a colder body.
39. The total entropy of an isolated system can never decrease. This is a statement of: — The Second Law of Thermodynamics
40. Which of the following is a condition for a process to be reversible? — The process is carried out infinitesimally slowly, maintaining equilibrium.
41. Which of the following conditions must be met for a process to be considered reversible? — The process must occur infinitely slowly, with the system always in equilibrium.
42. Which of the following conditions is necessary for a process to be reversible? — The system must be in equilibrium with its surroundings at all times.
43. The second law of thermodynamics places a fundamental limit on: — The efficiency of converting heat into work.
44. Which statement is true for any irreversible process? — The total entropy change of the system and surroundings is positive.
45. Which statement about reversible processes is correct? — They can be reversed by an infinitesimal change in conditions, restoring both system and surroundings to their original states.
46. Which statement is incorrect regarding reversible processes? — They always increase the total entropy.
47. For a heat engine, the coefficient of performance (COP) is defined as: — Work output / Heat input
48. The statement 'Heat cannot spontaneously flow from a colder body to a hotter body' is equivalent to which law? — Second Law of Thermodynamics
49. For a spontaneous process in an isolated system, the change in entropy (ΔS) must be: — ΔS > 0
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