Which of the following best explains how chemical formulas can be used to distinguish between a chemical change and a physical change?

• A. If the chemical formulas remain the same but the state of matter changes, a chemical change has occurred.
• B. If the chemical formulas of the substances before and after the change are the same, a chemical change has occurred.
• C. Chemical formulas cannot be used to determine whether a change is chemical or physical.
• D. If the chemical formulas of the substances before and after the change are different, a chemical change has occurred.

Answer: (D)

Verified step by step guidance

1. Understand that a chemical change involves the formation of new substances with different chemical formulas, indicating that the original substances have undergone a rearrangement of atoms.
2. Recognize that a physical change affects the state or appearance of a substance but does not alter its chemical formula or composition.
3. Use chemical formulas to compare the substances before and after the change: if the formulas are identical, the change is physical; if the formulas differ, a chemical change has occurred.
4. Note that changes in state of matter (solid, liquid, gas) without changes in chemical formulas represent physical changes, not chemical changes.
5. Conclude that the best way to distinguish between chemical and physical changes using chemical formulas is to check whether the formulas of the substances before and after the change are different, indicating a chemical change.