1. Formation of a gas: If bubbles or a gas are formed during a reaction, this could be a sign that a chemical change has taken place.
2. Color change: If the color of the reactants or products changes, this is evidence that a chemical change has occurred.
3. Temperature change: If the temperature of the system changes, either becoming hotter or cooler, this is an indication that the reaction is exothermic or endothermic, respectively.
4. Formation of a precipitate: If a solid substance forms during a reaction, this could be evidence that a chemical change has occurred.
what are four pieces of evidence that indicate a chemical change may have taken place?
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