Question

a process that changes one or more substances into new substances is a
physical change
dissolving process
phase change
chemical change
a piece of metal placed in acid produces bubbles of gas. what evidence shows that a chemical reaction occurred?

Explanation:

A chemical change (or chemical reaction) transforms substances into new ones. Physical change (like phase change) doesn't create new substances. Dissolving is a physical process. Gas production (bubbles) is a sign of chemical reaction as new gas substance forms.

Answer:

First question: Chemical change. Second question: Bubbles of gas (new substance) formed.