Which of the following is an example of a physical change in matter?

Melting an ice cube is indeed an example of a physical change in matter because it involves a transition from solid to liquid without altering the chemical composition of water. When ice melts, it changes its state due to the addition of heat, but the molecular structure of H2O remains the same throughout the process. This is characteristic of physical changes, which involve changes in state or appearance but do not result in the creation of a new substance.

In contrast, the other options represent chemical changes where the original substances undergo a transformation into different substances with distinct properties. For instance, combustion of wood involves a reaction with oxygen that produces ash, carbon dioxide, and water, fundamentally altering the wood. Rusting of iron is a reaction with oxygen and moisture that creates iron oxide, a completely different material from the original iron. Similarly, tarnishing of silver refers to a reaction with sulfur compounds in the air that produces silver sulfide, changing the original bright surface of silver to a dull appearance.