8.8: Calculate the ‘spin only’ magnetic moment of M2+(aq)(aq) ion (Z = 27) 

Z = 27
[Ar] 3d74s2
∴M2+=Ar3d7
3d7=      
i.e., 3 unpaired electrons
∴n=3
⇒n(n+2)=μ
⇒3(3+2)=μ
⇒15=μ
μ≈4BM