Which of the following phrases best describes a chemical change?

• A. Water freezing to form ice
• B. Salt dissolving in water
• C. Breaking a glass bottle
• D. Iron rusting when exposed to air

Answer: (D)

Verified step by step guidance

1. Understand the definition of a chemical change: it involves the formation of one or more new substances with different chemical properties and compositions from the original substances.
2. Analyze each option to determine if a new substance is formed:
3. Water freezing to form ice is a physical change because the chemical composition of H\_2O remains the same; only the state changes from liquid to solid.
4. Salt dissolving in water is also a physical change because the salt dissociates into ions but no new chemical substances are formed; the process is reversible.
5. Breaking a glass bottle is a physical change since the glass is only physically broken into smaller pieces without altering its chemical composition.
6. Iron rusting when exposed to air is a chemical change because iron reacts with oxygen and moisture to form a new substance, iron oxide (rust), which has different properties from iron.