Which statement best describes the third law of thermodynamics?

The third law of thermodynamics states that as the temperature of a perfect crystal approaches absolute zero, the entropy, or disorder, of the system approaches a constant minimum. Specifically, for a perfect crystal, that value is zero. This principle highlights the relationship between temperature and entropy, indicating that perfectly ordered states exist at absolute zero, where molecular motion is minimal.

In contrast, the other statements may relate to thermodynamic principles but do not accurately encapsulate the third law. For instance, the idea that energy cannot be created or destroyed reflects the first law of thermodynamics, while the notion that heat flows from hot to cold relates to the second law. The statement about energy systems tending toward equilibrium also pertains more to general thermodynamic behavior without being specific to the third law. The correct understanding of the third law emphasizes the unique behavior of entropy in perfectly ordered systems at absolute zero, which is key in thermodynamic studies.