Among the oxides CrO , Cr ₂ O ₃ and CrO ₃ , the amphoteric oxide dissolves in aqueous alkali to form a complex anion. The spin-only magnetic moment of the central metal ion in this complex anion is :

Step-by-step solution

The given oxides of chromium are CrO , Cr ₂ O ₃ and CrO ₃ . The acidic character of transition metal oxides increases with the increase in oxidation state. CrO (oxidation state +2 ) is basic. Cr ₂ O ₃ (oxidation state +3 ) is amphoteric. CrO ₃ (oxidation state +6 ) is acidic. The amphoteric oxide Cr ₂ O ₃ dissolves in aqueous alkali to form the chromite ion, [ Cr ( OH )₆]³⁻ or CrO ₂^- . In this complex anion, the oxidation state of chromium remains +3 . The electronic configuration of Cr is [ Ar ] 3 d ^5 4 s ^1 . T