Question

which of these are signs that a chemical reaction has taken place? select one: change in temperature production of a gas or solid product production of light all of the above change of color

Explanation:

• A change in temperature can occur during an exothermic (heat - releasing) or endothermic (heat - absorbing) chemical reaction.
• Production of a gas (effervescence) or a solid (precipitate) indicates new substances are formed, which is a sign of a chemical reaction.
• Production of light (such as in combustion reactions) shows a chemical change.
• A change of color often implies a chemical reaction as new substances with different electronic structures (which affect color) are formed.

Answer:

All of the above.