Q. The pair of lanthanoid ions which are diamagnetic is
A) $Gd^{3+}$ and $Eu^{3+}$
B) $Pm^{3+}$ and $Sm^{3+}$
C) $Ce^{4+}$ and $Yb^{2+}$
D) $Ce^{3+}$ and $Eu^{2+}$
Explanation
[Solution by Claude - not from source] $Ce^{4+}$ is $4f^0$ and $Yb^{2+}$ is $4f^{14}$: both have no unpaired electrons. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.