Number of colourless lanthanoid ions among the following is \_\_\_\_. $\mathrm{Eu}^{3+}, \mathrm{Lu}^{3+}, \mathrm{Nd}^{3+}, \mathrm{La}^{3+}, \mathrm{Sm}^{3+}$

JEE Main · 2024 · 09 Apr 2024 · Shift 1 · d and f Block Elements

Number of colourless lanthanoid ions among the following is ____.

Eu^{3 +}, Lu^{3 +}, Nd^{3 +}, La^{3 +}, Sm^{3 +}

Answer: 2

Colourless lanthanoid ions have

f^{0}

f^{14}

(no unpaired f-electrons capable of d–d/f–f colour):

L a^{3 +}

(

4 f^{0}

) and

L u^{3 +}

(

4 f^{14}

) — total 2. (

N d^{3 +}, S m^{3 +}, E u^{3 +}

are coloured.)

JEE Main · 2024 · 09 Apr 2024 · Shift 1 · Integer answer