Question

which scenario is an example of a physical change?
wood is burned in a campfire and is turned into ash and smoke.
a piece of metal is left in the rain and forms rust.
lead is melted into a liquid to form pellets.
yeast turns sugar into energy, water, and carbon dioxide gas.

Explanation:

A physical change alters the form of a substance but not its chemical identity, with no new substance formed.

• Burning wood creates new substances (ash, smoke) = chemical change.
• Rusting forms new iron oxide = chemical change.
• Melting lead only changes its state from solid to liquid (and back to solid for pellets); lead remains lead, no new substance = physical change.
• Yeast breaking down sugar creates new substances (energy, water, CO₂) = chemical change.

Answer:

Lead is melted into a liquid to form pellets.