Which term describes a change in matter that produces one or more new substances?

• A. Physical change
• B. Chemical change
• C. Phase change
• D. Reversible change

Answer: (B)

A change that results in new substances forming is a chemical change. This happens when bonds break and new bonds form, reconfiguring the atoms into substances with different properties. Examples include burning wood, which turns into ash and gases, or iron rusting to form iron oxide.

In contrast, a physical change only alters form, size, or state without changing the actual substance. Melting ice to liquid water changes appearance and state, but still results in water molecules; no new substance is created. A phase change is a type of physical change focused specifically on changing state (solid, liquid, gas) rather than composition. Reversibility describes whether a change can be undone, and while some physical changes are reversible and some chemical changes can be reversed under certain conditions, reversibility by itself does not define whether new substances are produced.