Chemical reactions - The transformation of chemical substance into a new chemical substance by making and breaking of bonds between different atoms is known as Chemical Reaction. Signs of a chemical reaction These factors denote that a chemical reaction has taken place- change of state of substance, change of color of substance,evolution of heat, absorption of heat, evolution of gas and evolution of light. Chemical Equation: The representation of chemical reaction by means of symbols of substances in the form of formulae is called chemical equation. E.g. - H 2 + O 2 ⇒ H 2 O Balanced Chemical Equation: A balanced chemical equation has number atoms of each element equal on both left and right sides of the reaction. *No...