Question

What is the oxidation number for `Ba`?

Answer 1

Barium typically displays a `+II` oxidation state in its compounds.

Explanation:

Barium salts, `BaX_2`, clearly have an oxidation state of `+II`. Neutral barium metal, of course has a `0` oxidation state, as it has neither donated nor accepted electrons.

That barium takes a `+II` oxidation state, is entirely consistent with its position in Group 2 of the Periodic Table, i.e. 2 valence electrons, which the metal LOSES when it forms an ionic compound.