A general impression exists that mass-energy interconversion takes place only in nuclear reaction and never in chemical reaction. This is strictly speaking, incorrect. Explain?

Einstein's mass-energy relation: E = m c2
The Einstein mass energy relation holds good not only for nuclear reactions, but also for chemical reactions.
In any chemical reaction, the totalmass of products is slightly smaller than the total mass of reactants.
In general, this small change in mass is negligible and not considered under macroscopic point of view.
But, in microscopic point of view, this small change in mass is also considerable, which produces an equivalent of energy as per Einstein's mass-energy relation. Example: Burning of coal