Answer: A solid forms when two liquids are mixed.
Explanation:
A physical reaction is defined as the reaction in which a change in shape, size takes place. No new substance gets formed in these reactions.
A chemical reaction is defined as the reaction in which a change in chemical composition takes place. A new substance is formed in these reactions.
1. A solid dissolves in liquid: Only the phase of the solid changes to aqueous and no new substance is formed, thus is a physical change.
2. A solid forms when two liquids are mixed: two liquids can forma solid only on chemical combination and formation of new substance.
3. A solid melts to a liquid when it is heated: Only the phase of the solid changes to liquid, no new substance is formed, thus is a physical change.
4. A solid metal changes shape: Only the shape of the solid changes, thus is a physical change.
