Answer : The rules of equalization of chemical reactions are: 1. In a chemical reaction, the reactants have to be written on the left side of the equal or arrow sign and the product on the right side. 2. If there are multiple reactants and multiple products in the reaction, they should be written with the plus sign. 3. The number of atoms of different elements on the left side of the equation and the number of atoms of the same element on the right side must be equal. 4. The physical state of the reactant and the product is written in the first bracket on the right side of the compound. For example , if solid , s ( s), liquid ( l ), gaseous ( g ), aqueous solution ( aq ) .