Which of these characteristics is a physical property of water?

The characteristic that indicates a physical property of water is its expansion when it freezes. This phenomenon occurs due to the unique molecular structure of water. As water freezes, the molecules arrange themselves into a crystalline lattice that is more spacious than in its liquid state, resulting in an increase in volume. This behavior is significant because it causes ice to float on water, which has important ecological implications for aquatic life in colder climates.

Understanding this property is critical in various contexts, including environmental science and funeral service practices where knowledge of water properties can come into play, such as in the embalming fluid composition and how it interacts with body tissues.

The characteristic of changing boiling point is also significant, but it relates more to conditions rather than being a fixed physical property. Conducting electricity typically pertains to ionic substances rather than pure water, and high density would imply a higher mass per unit volume than water actually possesses at standard temperature and pressure. Thus, the expansion of water upon freezing stands out as a fundamental physical property that is vital for understanding water's behavior in both natural and practical applications.