We can tell when a chemical reaction occurs by looking at the result. If the matter changes identity rather
than just form, then a (4). has occurred.

Calcium chloride +gold(1) oxide—>

Can someone me with questions 12 and 13 plz.

What do electromagnetic waves carry? how are they produced through which media can they move? where do they transfer energy? what do they not transfer? what do mechanical waves carry? how are they produced? through which media can they move? where do they transfer energy? what do they not transfer?