When a substance changes states, such as when it melts from a solid to a liquid, what type of change is occurring?

• A. A chemical change
• B. An irreversible change
• C. A nuclear change
• D. A physical change

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 new substances with different properties.
2. Recognize that changes in state (such as melting, freezing, boiling, or condensation) involve a change in the physical form of the substance without altering its chemical identity.
3. Note that melting from a solid to a liquid involves breaking intermolecular forces but does not break or form chemical bonds within the molecules themselves.
4. Identify that because the substance remains chemically the same before and after melting, this process is classified as a physical change.
5. Conclude that the correct classification for a substance melting from solid to liquid is a physical change, not a chemical, nuclear, or irreversible change.