Which of the following best describes a chemical change?

• A. A process that only alters the physical state of a substance without changing its chemical composition.
• B. A process that involves only a change in temperature but no change in substance.
• C. A process in which substances are transformed into new substances with different chemical properties.
• D. A change that can always be reversed by simple physical means.

Answer: (C)

Verified step by step guidance

1. Understand the definition of a chemical change: it involves the transformation of substances into new substances with different chemical properties and compositions.
2. Recognize that physical changes only affect physical properties such as state, shape, or temperature, without altering the chemical identity of the substance.
3. Identify that a chemical change results in the formation of new substances, which is often accompanied by observable signs such as color change, gas production, or formation of a precipitate.
4. Note that chemical changes are generally not easily reversible by simple physical means, unlike physical changes which can often be reversed.
5. Compare the given options and select the one that describes the formation of new substances with different chemical properties, as this best fits the definition of a chemical change.