Which of the following best describes a physical change?

A physical change is characterized by a transformation in the form or appearance of a substance without altering its chemical composition. Melting ice into water serves as a prime example of this concept, as it involves a change in state from solid to liquid due to the addition of heat. However, the molecular structure of water remains the same; H2O does not change into a different chemical substance.

On the other hand, breaking a chemical bond represents a chemical change, as it involves altering the composition of the substance. Rust forming on iron is another example of a chemical change, where iron reacts with oxygen to form iron oxide, fundamentally changing the material. Similarly, burning wood leads to combustion, resulting in new substances like carbon dioxide, ash, and other gases, which signifies a chemical change as well. Thus, the process of melting ice exemplifies a physical change as it retains the same molecular structure before and after the transformation.