JEE Main · 2024 · 30 Jan 2024 · Shift 1 · d and f Block Elements

Diamagnetic Lanthanoid ions are:

Answer: (B)

Solution

Ce : [Xe] 4 f^{1} 5 d^{1} 6 s^{2} \Rightarrow C e^{4 +} : [Xe] 4 f^{0}

— no unpaired electrons, diamagnetic.

La : [Xe] 4 f^{0} 5 d^{1} 6 s^{2} \Rightarrow L a^{3 +} : [Xe] 4 f^{0}

— also diamagnetic.

N d^{3 +}

(

4 f^{3}

) and

E u^{3 +}

(

4 f^{6}

) both carry unpaired electrons, so the diamagnetic pair is

L a^{3 +}

and

C e^{4 +}

JEE Main · 2024 · 30 Jan 2024 · Shift 1 · Single correct option