The pair of lanthanoid ions which are diamagnetic is
- Ce4+ and Yb2+
- Ce3+ and Eu2+
- Gd3+ and Eu3+
- Pm3+ and Sm3+
Answer
(1) Ce4+ and Yb2+
Solution
Diamagnetic ions have no unpaired electrons (4f0 or 4f14).
Ce4+: 4f0; Yb2+: 4f14 both diamagnetic.
Ce3+ 4f1, Eu2+ 4f7, Gd3+ 4f7, Eu3+ 4f6, Pm3+ 4f4, Sm3+ 4f5 are all paramagnetic.
Answer: (1)