(આપેલ : પરમાણુ કમાંક : $Ti : 22, V : 23, Cr : 24, Co : 27$)
No. of unpaired $\mathrm{e}^{-}$in $\mathrm{Co}^{+3}\left[3 \mathrm{~d}^6\right]=4$
Hence $\mu=\sqrt{n(n+2)}=\sqrt{24} B M$
Nearest integer $=5$
(At. nos. $Mn = 25, Fe = 26, Co = 27, Ni = 28$)