Question

The magnetic moment of $M^{x+}$ (atomic number = 25) is $\sqrt{15}$ BM. Then, the oxidation number $x$ of $M$ is :

• A. 3
• B. 4
• C. 2
• D. 1

Answer 1

The correct option is B 4

The electronic configuration of $M^{x+}(Z=25)$ is :

$1s^2,2s^2,2p^6,3s^2,3p^6,3s^5,4s^2$

Magnetic moment $=\sqrt{n(n+2)}$ BM

$=\sqrt{5(5+2)}$ BM $=\sqrt{35}$ BM

Given, magnetic moment = $\sqrt{15}$ BM $=\sqrt{3(3+2)}$ BM

Hence, unpaired electrons $=3$

$\therefore$ The oxidation number $x$ is $7-3=$ $4$.

Hence, the correct option is B.