Question

Which of the following pair of transition metal ions have the same calculated values of magnetic moment?

• A. $Ti^{2+}$ and $V^{2+}$
• B. $Fe^{2+}$ and $Cu^{2+}$
• C. $Cr^{2+}$ and $Fe^{2+}$
• D. $CO^{2+}$ and $Ti^{2+}$

Answer 1

Answer: (C)

$Cr^{2+} (Z=24): $
$[Ar]3d^{4} 4s^{0}; $ four unpaired electrons
$Fe^{2+} (Z=26): $
$[Ar]3d^{6} 4s^{0}; $ four unpaired electrons
$Cr^{2+}$ and $Fe^{2+}$ have same number of unpaired electrons hence they have the same value of magnetic moment.