Question

Is combustion a physical or chemical change? Why?

Answer 1

Chemical.

Explanation:

Look at the chemical make-up of the substances after the change, and compare them with the chemical make-up before the change. Is it different?

When ice melts, the chemical makeup before is `H_2O(s)` and after is `H_2O(l)`. The physical state has changed, but the chemical make-up is the same. Thats a physical change.

Combustion, however.....start with carbon, and oxygen `C(s) + O_2(g)`, and end up with carbon dioxide `CO_2(g)` a completely different molecule - that's a chemical change.

(Don't get sucked into the "physical changes are reversible, chemical changes aren't" nonsense....you'll eventually regret it if you do!)