3 physical changes:
1. Ice melting involves a change from a solid to a liquid and the substances maintain the properties of water because the molecules never change.
2. Water boiling is a physical change as water molecules vibrate faster, they enter the gas phase and become water vapor.
3. Rubbing alcohol left uncovered will evaporate quickly into the air. It turns to a gas but maintains the properties of alcohol.
4 chemical changes:
iron rusting (iron oxide forms)gasoline burning (water vapor and carbon dioxide form)eggs cooking (fluid protein molecules uncoil and crosslink to form a network)bread rising (yeast converts carbohydrates into carbon dioxide gas)
