Which gas is usually liberated when an acid reacts with a metal?

When a metal reacts with an acid then Hydrogen ($H_2$) gas is usually liberated

For example, Zinc ($Zn$) reacts with dil. Hydrochloric acid ($HCl$) to form Zinc chloride ($ZnC{l}_2$) and Hydrogen ($H_2$) gas are products and the chemical reaction is as follows.

$\underset{Zinc}{Zn\left(s\right)}+\underset{Hydrochloricacid}{HCl\left(l\right)}\to \underset{Zincchloride}{ZnC{l}_2\left(s\right)}+\underset{Hydrogen}{H_2\left(g\right)}$