Which law states that the entropy of the universe increases in a spontaneous process?

• A. Second Law of Thermodynamics
• B. First Law
• C. Third Law
• D. Zeroth Law

Answer: (A)

Entropy measures how spread out energy is and how many microscopic ways a system can arrange itself. In spontaneous changes, energy tends to disperse, increasing the overall disorder when you include the surroundings. The second law of thermodynamics states that the entropy of the universe does not decrease for a spontaneous process. In practical terms, the total entropy change, combining the system and its surroundings, is positive for spontaneous transformations and zero only for ideal reversible ones. If a process releases heat to the surroundings, the surroundings gain entropy, often making the total increase. The other laws describe different ideas: the first law is about energy conservation, the third law deals with entropy at absolute zero, and the zeroth law defines temperature through thermal equilibrium.