Question

The pair of Lanthanoid ions which are diamagnetic is

• A. Ce⁴⁺ and Yb²⁺
• B. Ce³⁺ and Eu²⁺
• C. Gd³⁺ and Eu³⁺
• D. Pm³⁺ and Sm³⁺

Answer 1

The Correct Option is A

1. Diamagnetic ions have no unpaired electrons. 

2. $Ce^{4+}$ ([Xe]) has no unpaired electrons. 

3. $Yb^{2+}$ ([Xe]$4f^{14}$) has fully paired 4$f$-orbitals.

Answer 2

Step 1: Identify Diamagnetic Ions

Diamagnetic ions are those that do not have unpaired electrons, meaning their electron configuration is fully paired.

Step 2: Examine the Given Ions

• Ce³⁺: Has 1 unpaired electron, so it is paramagnetic.
• Eu²⁺: Has 7 unpaired electrons, so it is paramagnetic.
• Gd³⁺: Has 7 unpaired electrons, so it is paramagnetic.
• Eu³⁺: Has no unpaired electrons, so it is diamagnetic.
• Ce⁴⁺: Has no unpaired electrons, so it is diamagnetic.
• Yb²⁺: Has no unpaired electrons, so it is diamagnetic.

Step 3: Conclusion

The correct answer is:

Option (1): Ce⁴⁺ and Yb²⁺ are diamagnetic.