What is NOT a characteristic of a chemical reaction?

In a chemical reaction, various observable changes occur as reactants transform into products. These changes can include color changes, the formation of gas, and the creation of solids, all of which are indicative of new substances being formed.

The absence of mass change is not a characteristic of a chemical reaction because, according to the law of conservation of mass, mass is neither created nor destroyed in a closed system. In a typical chemical reaction, the total mass of the reactants will equal the total mass of the products. This principle indicates that while the appearance and state of matter may change during a reaction, the overall mass remains constant. Thus, the notion that there would be no mass change during a chemical reaction contradicts this foundational scientific principle.