Question

The calculated spin only magnetic moment of $C{o}^{2+}$ ion is

• A. $4.90\text{BM}$
• B. $5.92\text{BM}$
• C. $2.84\text{BM}$
• D. $3.87\text{BM}$

Answer 1

The correct option is D $3.87\text{BM}$

Electronic configuration of $Co\to \left[Ar\right]3d^{7}4s^2$
Electronic configuration of $C{o}^{2+}\to \left[Ar\right]3d^7$

Number of unpaired $e^{-}=3$
Spin only magnetic moment $=\sqrt{n(n+2)}\text{BM}$
$=\sqrt{3(3+2)}$
$=\sqrt{15}\text{BM}$
$=3.87\text{BM}$