Question

I. A chemical change breaks bonds, forms new substances and is irreversible.

II. Reordering the intermolecular forces is indicative of a chemical change.

III. During a physical change the substance remains the same, no bonds are broken, and the process is reversible.

IV. Permanently altering the makeup of the substance is characteristic of a physical change.

Which conclusion(s) best elaborate(s) on the difference(s) between a chemical change and a physical change?
Responses

A I & III
I & III

B II & IVII & IV

C III & IIIII & II

D IV & I

Answer 1

Answer: A (I & III).

Explanation:
- I describes a chemical change correctly in that chemical bonds are broken and new substances form (note: not all chemical reactions are absolutely irreversible — some are reversible/equilibria — but the statement captures the key distinction).
- III correctly describes a physical change: the identity of the substance remains the same, chemical bonds are not broken, and physical changes are often reversible.

II is wrong because reordering intermolecular forces (e.g., melting, evaporation) is a physical change, not a chemical one. IV is wrong because permanently altering the makeup of a substance describes a chemical change, not a physical change.