Which of the following lists includes common indicators that a chemical reaction has occurred?

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

Answer: (C)

Verified step by step guidance

1. Step 1: Understand that a chemical reaction involves the making or breaking of chemical bonds, resulting in new substances with different properties.
2. Step 2: Identify common indicators of chemical reactions, which typically include observable changes such as change in color, formation of a gas (bubbling), formation of a precipitate (solid), change in temperature (exothermic or endothermic), and change in odor.
3. Step 3: Recognize that physical changes like evaporation, condensation, sublimation, deposition, expansion, melting, boiling, dissolving, and freezing do not produce new substances and thus are not indicators of chemical reactions.
4. Step 4: Note that changes in mass, pressure, volume, or density can be related to physical changes or experimental conditions but are not definitive indicators of a chemical reaction by themselves.
5. Step 5: Conclude that the list containing 'change in color, formation of a gas, formation of a precipitate, change in temperature, change in odor' correctly represents common indicators that a chemical reaction has occurred.