Question

Which one of the following is a diamagnetic ion ?

• A. $C{o}^{2+}$
• B. $C{u}^{2+}$
• C. $M{n}^2$+
• D. $S{c}^{3+}$

Answer 1

Answer: (D)

$C{o}^{2+}$ (Z = 27) : $[Ar{]}^{18}3d^7$ (3 unpaired electrons)
$C{u}^{2+}$ (Z = 29) : $[Ar{]}^{18}3d^9$ (1 unpaired electrons)
$M{n}^{2+}$ (Z = 25): $[Ar{]}^{18}3d^5$ (5 unpaired electrons)
$S{c}^{3+}$ (Z = 21): $[Ar{]}^{18}3d^0$ (No unpaired electron)
$S{c}^{3+}$ with no unpaired electron will be diamagnetic