In Na2O, what is the oxidation state of oxygen?

In Na₂O oxidation state of O is -2.

Explanation

The oxidation state of an atom (sometimes also referred to as the oxidation number) in a chemical compound gives insight into the number of electrons lost it and, therefore, describes the extent of oxidation of the atom.

 Na₂O

O is more electronegative than Na, hence, Na is given +1 oxidation state and O shows oxidation state as given below

Let us assume that the oxidation state of oxygen in Na₂O is x

2(+1)+ (x)=0

+2 +x= 0

x=-2

In Na₂O oxidation state of O is -2.