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NEET Chemistry QUESTION #7410
Question 1
Which of the following lanthanoid ions is diamagnetic? (Atomic numbers: Ce = 58, Sm = 62, Yb = 70)
  • \(\text{Yb}^{2+}\)✔️
  • \(\text{Ce}^{2+}\)
  • \(\text{Sm}^{2+}\)
  • \(\text{Eu}^{2+}\)
Correct Answer Explanation
Diamagnetic means all electrons are paired (no unpaired electrons).

\(\text{Yb}^{2+}\): Yb (Z=70) = [Xe] 4f¹⁴ 6s². Yb²⁺ = [Xe] 4f¹⁴ → completely filled f subshell → all electrons paired → diamagnetic

Ce²⁺ = [Xe]4f², Sm²⁺ = [Xe]4f⁶, Eu²⁺ = [Xe]4f⁷ — all have unpaired f-electrons and are paramagnetic.