Which of the following best describes how a chemical change differs from a physical change?

• A. A chemical change only affects the state of matter, while a physical change alters the chemical composition.
• B. A chemical change is always reversible, whereas a physical change is always irreversible.
• C. A chemical change results in the formation of new substances with different chemical properties, while a physical change does not alter the chemical identity of a substance.
• D. A chemical change involves only changes in temperature, while a physical change involves changes in color.

Answer: (C)

Verified step by step guidance

1. Understand the definitions: A physical change affects the form or state of a substance without changing its chemical identity, while a chemical change results in the formation of one or more new substances with different chemical properties.
2. Identify key characteristics of physical changes, such as changes in state (solid, liquid, gas), shape, or size, which do not involve breaking or forming chemical bonds.
3. Recognize that chemical changes involve breaking old bonds and forming new bonds, leading to substances with different compositions and properties.
4. Evaluate the given options by comparing them to these definitions to determine which statement correctly distinguishes chemical changes from physical changes.
5. Conclude that the correct description is the one stating that chemical changes produce new substances with different chemical properties, whereas physical changes do not alter the chemical identity of the substance.