n a chemical reaction, delta H represents the sum of the heats of formation, commonly measured in kilojoules per mol (kJ/mol), of the products minus the sum of those of the reactants. The letter H in this form is equal to a thermodynamic quantity called enthalpy, representing the total heat content of a system.
The answer that would best complete the given statement above is the term ATOM. <span>The smallest unit which maintains the physical properties of a compound is an ATOM. But for a compound, it would be molecule. Hope this answers your question.</span>
