Question

The basicity of HCl is ___

Answer 1

The basicity of an acid is defined as the no. of ionizable hydrogen $H^{+}$ ions present in one molecule of the acid. Whereas, the acidity of a base is defined as the no. of ionizable hydrogen ions $O{H}^{-}$ present in one molecule of that base.

One molecule of HCl releases one hydronium ion in aqueous solution. Hence, its basicity is one.