Question

What must be done to be certain that a chemical change has taken place?
a. Check for the production of bubbles before and after the change.
b. Demonstrate that a release of energy occurred after the change.
c. Check the composition of the sample before and after the change.
d. Demonstrate that energy was absorbed by the reactants after the change.

Answer 1

Answer:

c. Check the composition of the sample before and after the change.

Explanation:

In a chemical change there is change in the chemical composition. So the chemical composition of the reactants is different than the chemical composition of the products. During a chemical change the bonds in the reactants are broken and new bonds are formed in the products.