Question

which statement is the best description of a chemical reaction?
the combustion of a substance
forming or breaking bonds
mixing two substances
the decomposition of particles

Explanation:

A chemical reaction involves the making and breaking of chemical bonds to transform substances. Combustion is a type of reaction, mixing may not always be a chemical reaction, and decomposition of particles is too vague. Forming or breaking bonds best describes the essence of a chemical reaction.

Answer:

forming or breaking bonds