What happens when a metal is added to an acid?
It produces H and some other products(s) depending on what metal and what acid you used. You also forgot that you add acid. You aren't supposed to add metal, you are supposed to add the acid for safety.
Depends on the metal and the acid.
Depending on the acid it can "eat through the metal"(Melts a hole) while some acids are not strong enough to eat through metal. If I might ask, what kind of acid?