Which is the best evidence that a chemical change has occurred? a. release of energy b. temperature change c. change of state d. formation of a new substance

d

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.