Which of the following is an example of a chemical change?

Iron rusting is a prime example of a chemical change because it involves a reaction between iron and oxygen in the presence of moisture, resulting in the formation of iron oxide, commonly known as rust. This process alters the chemical composition of the original material (iron), leading to the creation of a new substance that has different properties from the starting material.

In contrast, melting ice is a physical change, as it simply involves a phase transition from solid to liquid without changing the chemical structure of the water molecules. Similarly, breaking glass and mixing sugar in water also represent physical changes. Breaking glass changes the shape and size of the glass but does not alter its chemical composition, while mixing sugar in water creates a solution, but both the sugar and water retain their original chemical identities throughout the process.