Question

which would show an example of how physical changes are reversible? cutting a gold bar in two pieces and then putting the pieces next to each other burning a match and then relighting it melting tin and then cooling it into a mold combining sodium and chlorine to make the new material of table salt

Explanation:

Physical changes involve changes in state or form without altering the chemical composition. Melting tin (changing from solid to liquid) and then cooling it back to a solid in a mold is a physical change that is reversible. Cutting a gold - bar and putting pieces together is not truly a reversible change in the sense of the original state. Burning a match is a chemical change. Combining sodium and chlorine is a chemical reaction forming a new compound.

Answer:

melting tin and then cooling it into a mold