Which statement reflects the second law of thermodynamics?

• A. Every energy transfer or transformation increases the entropy of the universe.
• B. Energy cannot be created or destroyed.
• C. Entropy decreases in spontaneous processes.
• D. Heat can flow from cold to hot spontaneously.

Answer: (A)

The second law is about entropy and irreversibility. In real energy transfers or transformations, the total entropy of the universe tends to increase because energy spreads into more possible microstates and becomes more dispersed. Saying that every energy transfer or transformation increases the entropy of the universe captures that overall tendency: real processes are not perfectly reversible, so entropy rises.

The other ideas don’t fit as well: the conservation of energy describes the first law, not the second; entropy decreasing in spontaneous processes would violate the second law; heat flowing from cold to hot on its own contradicts the natural direction of spontaneous heat flow unless external work is applied.