The pair of lanthanoid ions which are diamagnetic is

The pair of lanthanoid ions which are diamagnetic is
  1. $\mathrm{Ce}^{3+}$ and $\mathrm{Eu}^{2+}$
  2. $\mathrm{Gd}^{3+}$ and $\mathrm{Eu}^{3+}$
  3. $\mathrm{Pm}^{3+}$ and $\mathrm{Sm}^{3+}$
  4. $\mathrm{Ce}^{4+}$ and $\mathrm{Yb}^{2+}$

Solution

Magnetic moment $\mu=\sqrt{n(n+2)}$ $\mathrm{n} \rightarrow$ number of unpaired electron
Hence $\mathrm{Ce}^{4+}$ and $\mathrm{Yb}^{2+}$ are only diamagnetic.

Asked in: NEET 2024

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