Hello,

Acidity of base is determined for bases containing -OH group and in layman terms acidity of a base is determined as Number of Hydrogen ions it can neutralise. For eg NaOH contains 1 -OH ion and Ca(OH)2 contains 2 -OH ion so NaOH and Ca(OH)2 are monoacidic and diacidic bases respectively as they can neutralise 1 and 2 Hydrogen ions respectively.

Now the Lithium Oxide is a basic oxide as generally most of the metallic oxides are basic in nature, but the concept of acidity isn't applied to such bases. The reason of basic nature of metallic oxides is due to the nature of bonding and not due to presence of OH group.

Thank you.