Which is not proof that a chemical change has occurred?

a. the color changes

B. a precipitate forms

C. the substance melts

D. bubbles are produced

C

Explanation:

When a substance undergoes a chemical change, the chemical properties of the substance changes, and it usually combines with another substance or forms products that form a precipitate.

When a substance melts, there is not any actual chemical change to the substance. Yes, there is a physical change that alters the physical properties of the substance, but no chemical change happens.

A colour change can occur because of two substances interacting, and in this interaction, the substances chemically alter each other.

A precipitate being formed and bubbles being produces is a result of chemical changes that result in the chemicals producing products in a different state than what they originally came in.

the substance melts

Choice C

Explanation:

A chemical change refers a process by which one substance changes into a new substance with different properties with the formation of one or more new substances.

Color change, formation of a precipitate and production of bubbles all indicate the occurrence of a chemical change. On the other hand, melting is purely a physical change since no new substance is formed and the process can easily be reversed through freezing.