(a) Define a chemical reaction.

(b) What is a chemical equation?

(c) Why do we need to balance chemical equations?

(a) Any chemical change in matter which involves its transformation into one or more new substances is called a chemical reaction.

(b) A chemical reaction can be represented with the help of symbols or the formulae of the elements and the compounds taking part in the reaction and the product formed, in the form of a chemical equation.

(c) A chemical equation needs to be balanced so as to make the number of atoms of the reactants equal to the number of atoms of the products because a chemical reaction is just a rearrangement of atoms. The atoms themselves are neither created nor destroyed during the course of a chemical reaction.