The acid equations
The reactions taking place in each case are given below as balanced chemical equations.
With dilute hydrochloric acid
Mg + 2HCl → MgCl2 + H2
2Al + 6HCl → 2AlCl3 + 3H2
Zn + 2HCl → ZnCl2 + H2
Fe + 2HCl → FeCl2 + H2
One pattern in all four
metal + acid → salt + hydrogen. Every one is a single displacement reaction — the metal displaces the hydrogen in the acid.
The same with other acids
Most metals also react with dilute sulphuric (H2SO4) and dilute nitric (HNO3) acids and give off hydrogen (H2) gas.
Mg + H2SO4 → MgSO4 + H2
Why copper is not in the list
Copper (Cu) does not react with dilute hydrochloric (HCl) acid. So there is no equation for it — because there is no reaction.
The conclusion
The rate at which dilute acids react with metals also varies with the kind of metal.