Which of the following scenarios most likely involves a chemical change?

• A. Breaking a glass window
• B. Ice melting into liquid water
• C. Salt dissolving in water
• D. Iron rusting when exposed to air

Answer: (D)

Verified step by step guidance

1. Understand the difference between physical and chemical changes. A physical change affects the form of a substance but not its chemical composition, while a chemical change results in the formation of one or more new substances with different properties.
2. Analyze each scenario to determine if the substance's chemical identity changes: Breaking a glass window changes only the shape (physical change), ice melting changes the state from solid to liquid but remains H2O (physical change), salt dissolving in water separates ions but does not change their chemical identity (physical change).
3. Consider the scenario of iron rusting. This involves iron reacting with oxygen in the air to form iron oxide, a new substance with different chemical properties, indicating a chemical change.
4. Recognize that rusting is an example of oxidation, a common chemical reaction where a metal reacts with oxygen to form an oxide, confirming the chemical nature of the change.
5. Conclude that among the given options, iron rusting when exposed to air is the scenario that most likely involves a chemical change.