During a chemical change, what happens to the molecules of a substance?

• A. The molecules remain unchanged, but their physical state may change.
• B. The molecules are rearranged to form new substances with different chemical properties.
• C. The molecules are compressed closer together, but their chemical structure stays the same.
• D. The molecules are only separated without any change in their composition.

Answer: (B)

Verified step by step guidance

1. Understand that a chemical change involves a transformation at the molecular level, where the original substances are converted into new substances.
2. Recall that during a chemical change, the bonds between atoms in the molecules are broken and new bonds are formed, resulting in molecules with different chemical compositions and properties.
3. Recognize that this rearrangement of atoms means the molecules themselves are changed, not just their physical arrangement or state.
4. Contrast this with physical changes, where molecules remain the same but may change their physical state (solid, liquid, gas) or arrangement without altering their chemical structure.
5. Conclude that the correct description of what happens during a chemical change is that molecules are rearranged to form new substances with different chemical properties.