What is an example of a physical change?

Ice melting is indeed an example of a physical change because it involves a change in the state of matter from solid to liquid without altering the chemical composition of the substance. When ice melts, it retains its molecular structure; water remains H₂O whether in solid (ice) or liquid form (water). This transformation can be reversed, as the water can freeze again to become ice.

In contrast, burning wood results in combustion, which is a chemical change that alters the wood's molecular structure and produces new substances such as ash and gases. Similarly, iron rusting is a chemical change that occurs when iron reacts with oxygen and moisture, forming iron oxide. Milk souring represents a chemical change as well, as it involves the growth of bacteria and the production of acids, resulting in a different chemical composition and properties. Understanding the differences between physical and chemical changes is fundamental in studying matter and its interactions.