Which of the following best describes what happens during a chemical change?

• A. New substances with different chemical properties are formed.
• B. The physical state of a substance changes, but its chemical identity remains the same.
• C. Energy is always absorbed without any change in composition.
• D. The substance only changes its shape or size.

Answer: (A)

Verified step by step guidance

1. Understand that a chemical change involves a transformation where the original substances are converted into new substances with different chemical properties and compositions.
2. Recognize that during a chemical change, bonds between atoms are broken and new bonds are formed, resulting in substances that have different chemical identities than the starting materials.
3. Contrast this with physical changes, where the substance may change its physical state (like solid to liquid) or shape, but its chemical identity remains unchanged.
4. Note that energy changes (absorption or release) can occur in both chemical and physical changes, so energy absorption alone does not define a chemical change.
5. Conclude that the best description of a chemical change is the formation of new substances with different chemical properties.