d and f Block Elements Part 2

A first row transition metal with highest enthalpy of atomisation, upon reaction with oxygen at high temperature forms oxides of formula M2On (where n=3,4,5 ). The 'spin-only' magnetic moment value of the amphoteric oxide from the above oxides is ______ BM
(near integer)
(Given atomic number: Sc:21,Ti:22,V:23, Cr:24,Mn:25,Fe:26,Co:27,Ni:28,Cu:29, Zn:30)