JEE Main · 2024 · Shift-ImediumDNF-038

Diamagnetic Lanthanoid ions are:

d & f-Block Elements · Class 12 · JEE Main Previous Year Question

Question

Options

a
$\text{Nd}^{3+}$ and $\text{Eu}^{3+}$
b
$\text{La}^{3+}$ and $\text{Ce}^{4+}$
✓
c
$\text{Nd}^{3+}$ and $\text{Ce}^{4+}$
d
$\text{Lu}^{3+}$ and $\text{Eu}^{3+}$

Correct Answerb

$\text{La}^{3+}$ and $\text{Ce}^{4+}$

Detailed Solution

Diamagnetic = all electrons paired = $4f^0$ or $4f^{14}$

| Ion | Z | Config | 4f electrons | Magnetic | |-----|---|--------|--------------|----------| | $\text{La}^{3+}$ | 57 | [Xe] | $4f^0$ | Diamagnetic ✓ | | $\text{Ce}^{4+}$ | 58 | [Xe] | $4f^0$ | Diamagnetic ✓ | | $\text{Nd}^{3+}$ | 60 | [Xe] $4f^3$ | $4f^3$ | Paramagnetic ✗ | | $\text{Eu}^{3+}$ | 63 | [Xe] $4f^6$ | $4f^6$ | Paramagnetic ✗ | | $\text{Lu}^{3+}$ | 71 | [Xe] $4f^{14}$ | $4f^{14}$ | Diamagnetic ✓ |

Option (2): Both $\text{La}^{3+}$ ( $4f^0$ ) and $\text{Ce}^{4+}$ ( $4f^0$ ) are diamagnetic. ✓

Answer: Option (2) — $\text{La}^{3+}$ and $\text{Ce}^{4+}$

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