basic anhydrides....?

Question

Which oxides are basic anhydrides??
Na2O
BaO
ZnO

thanks!

Answer 1

A basic anhydride is a compound that is formed after you remove water from a basic solution. It basically means: which of the choices will produce a base if you add water (H2O)?

Na2O + H2O -> 2NaOH
BaO + H2O -> Ba(OH)2
ZnO + H2O -> (I don't know this one)

But I think the rule is, add a metal oxide to water and you get a base. So the answer would be whichever of these oxides has a metal on it.

Answer 2

The first two.
ZnO is amphoteric.