Question

the basic unit of matter that cannot be broken down further by chemical means 8 points neutron proton atom electron the transformation of one or more substances into one or more new substances with different properties; also known as a chemical change 8 points combustion reaction chemical reaction chemical constant physical change a substance that takes part in a chemical reaction; found on the left - hand side of the arrow in a chemical equation * 9 points reactant element atom catalyst

Explanation:

1. An atom is the basic unit of matter that cannot be broken down further by chemical means. Neutrons, protons, and electrons are sub - atomic particles.
2. A chemical reaction is the transformation of one or more substances into one or more new substances with different properties, also known as a chemical change. Combustion is a type of chemical reaction, a chemical constant is a different concept, and a physical change does not result in new substances.
3. Reactants are substances that take part in a chemical reaction and are found on the left - hand side of the arrow in a chemical equation. Elements and atoms are more fundamental units, and a catalyst is not a reactant in the traditional sense as it is not consumed in the reaction.

Answer:

1. C. atom
2. B. chemical reaction
3. A. reactant