The metal displaces hydrogen atoms from the acids as hydrogen gas and forms a compound called a salt.
Thus, the reaction of a metal with an acid can be summarised as –
Acid + Metal → Salt + Hydrogen gas
The reaction that takes place can be written as follows.
2 NaOH (aq) + Zn (s) → Na2ZnO2 (s) + H2 (g)
We find again that hydrogen is formed in the reaction. However, such reactions are not possible with all metals