Question

Which of the following pair of transition metal ions are diamagnetic?

• A. $Ti^{2+}$ and $Mn^{2+}$
• B. $Mn^{2+}$ and $Ni^{2+}$
• C. $V^{2+}$ and $Cr^{2+}$
• D. $Co^{2+}$ and $Ni^{2+}$
• E. $Sc^{3+}$ and $Zn^{2+}$

Hint:

$Sc^{3+}$, $Ti^{4+}$, $Zn^{2+}$, and $Cu^{+}$ are common diamagnetic transition metal ions.

Answer 1

Answer: (E)

Step 1: Concept
Diamagnetic species have no unpaired electrons ($d^0$ or $d^{10}$ configurations).

Step 2: Meaning
Paramagnetic species contain one or more unpaired electrons.

Step 3: Analysis
$Sc^{3+}$ has configuration $[Ar]3d^0$ (0 unpaired). $Zn^{2+}$ has configuration $[Ar]3d^{10}$ (0 unpaired).

Step 4: Conclusion
Both ions have fully filled or empty d-shells, making them diamagnetic.
Final Answer: (E)