Question

which scenarios are definite signs that a chemical reaction has occurred? (select all that apply) two liquids are mixed together and release a light. blue and yellow paint mix to make green paint. a piece of iron begins to rust. water is heated and releases a gas.

Explanation:

• When two liquids mix and release light, it indicates a chemical reaction as new substances are formed with energy release.
• Rusting of iron is a chemical reaction (oxidation) where iron reacts with oxygen and moisture to form iron oxide.
• Mixing blue and yellow paint is a physical change (color mixing, no new substance).
• Heating water to release gas (steam) is a physical change (phase change, no new substance).

Answer:

• Two liquids are mixed together and release a light.
• A piece of iron begins to rust.