Question

What do these changes have in common? :

using a large magnet to remove pieces of iron from a junkyard, crushing a mineral into powder
Select all that apply
1)both conserve mass
2)both are caused by cooling
3)both are caused by heating
4)both are only physical changes

Answer 1

4, because you are not altering the chemical makeup of the substances by doing these things. Hopes this helps! :)