Acid + Active metal ==> Salt + Hydrogen

eg. Hydrochloric acid + magnesium ==> Magnesiium chloride + hydrogen gas

   2HCl(aq) + Mg(s) ==+ MgCl₂(aq) + H₂(g)

All active metals are above 0.00 V (the hydrogen half cell) in the standard reduction table. Eg. Zn, Mg, Fe, etc.