Which of the following best describes the difference between a chemical change and a physical change?

• A. A chemical change involves only changes in temperature, while a physical change involves changes in color.
• B. A chemical change is always reversible, while 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 composition of a substance.
• D. A chemical change only affects the state of matter, while a physical change creates new substances.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the definitions of chemical and physical changes. A chemical change involves a process where the original substances transform into new substances with different chemical properties and compositions.
2. Step 2: Recognize that a physical change affects only the physical properties of a substance, such as its state, shape, or color, but does not change its chemical identity or composition.
3. Step 3: Evaluate the options given by comparing them to these definitions. For example, changes in temperature or color alone do not necessarily indicate a chemical change, as they can occur in physical changes as well.
4. Step 4: Note that reversibility is not a definitive criterion because some chemical changes can be reversible and some physical changes can be irreversible.
5. Step 5: Conclude that the best description is the one stating that a chemical change results in new substances with different chemical properties, whereas a physical change does not alter the chemical composition of the substance.