Which of the following lists includes five common signs that a chemical change has occurred?

• A. Change in shape, melting, boiling, dissolving, and freezing
• B. Color change, formation of a precipitate, evolution of a gas, temperature change, and production of light
• C. Increase in mass, decrease in volume, change in density, change in pressure, and formation of crystals
• D. Evaporation, condensation, sublimation, deposition, and expansion

Answer: (B)

Verified step by step guidance

1. Understand the difference between physical and chemical changes. Physical changes affect the form of a substance but not its chemical composition, while chemical changes result in the formation of new substances with different properties.
2. Identify common signs of chemical changes, which typically include indicators such as color change, formation of a precipitate (solid), evolution of a gas (bubbling or fizzing), temperature change (exothermic or endothermic reactions), and production of light (such as in combustion).
3. Review each list provided in the problem and classify the changes as physical or chemical. For example, melting, boiling, dissolving, and freezing are physical changes because they involve changes in state or form without altering chemical identity.
4. Recognize that the list containing 'color change, formation of a precipitate, evolution of a gas, temperature change, and production of light' corresponds to common signs of chemical changes.
5. Conclude that the correct list includes these five signs because they indicate that a chemical reaction has occurred, producing new substances or energy changes.