The correct name for N2O3 is nitrogen(iii) oxide.
Explanation: In chemical nomenclature, the name of a compound is determined by the oxidation state of the elements involved. In the case of N2O3, nitrogen has an oxidation state of +3. This is because there are two nitrogen atoms contributing a total of +6 charge, balanced by three oxygen atoms, each with a -2 charge, totaling -6. Therefore, the correct nomenclature uses the Roman numeral (iii) to indicate the oxidation state of nitrogen in this compound. Thus, N2O3 is called nitrogen(iii) oxide.