Q. Which of the following lanthanoid ions is diamagnetic ? (At. No. Ce = 58, Sm = 62, Eu = 63, Yb = 70)
A) Ce²⁺
B) Sm²⁺
C) Eu²⁺
D) Yb²⁺
Explanation
[Solution from source] Yb (Z = 70) is [Xe]4f¹⁴6s², so Yb²⁺ is 4f¹⁴ with every electron paired: diamagnetic. Ce²⁺ (4f²), Sm²⁺ (4f⁶) and Eu²⁺ (4f⁷) all have unpaired f electrons. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.