1. chemical reactions occur when new products are formed, ie. product is different to reactant(s). u can tell a chem reaction has occured if theres colour change, gas (ie bubbles) produced, energy released (ie. heat, light, etc), and many other things but cant rmb off the top of my head
phys reactions are when product = reactant, eg. liquid water to steam. its H20 --> H20. no change in product/reactant, only change in states
3. a phys property is like colour, texture.. something u can see, feel, etc
