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

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Step 1: Analyze electronic configurations La 3+ : [Xe]4f 0 (No unpaired electrons, colourless). Lu 3+ : [Xe]4f 14 (No unpaired electrons, colourless). Nd 3+ : [Xe]4f 3 (Unpaired electrons, coloured). Sm 3+ : [Xe]4f 5 (Unpaired electrons, coloured). Eu 3+ : [Xe]4f 6 (Unpaired electrons, coloured). Step 2: Count colourless ions Lanthanide ions that are colourless: La 3+ and Lu 3+ . Final Answer: 2.

Number of colourless lanthanoid ions among the following is ____.
\[ \text{Eu}^{3+}, \, \text{Lu}^{3+}, \, \text{Nd}^{3+}, \, \text{La}^{3+}, \, \text{Sm}^{3+} \]

Correct Answer: 2

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Top Questions on The Lanthanoids

Questions Asked in JEE Main exam

Number of colourless lanthanoid ions among the following is ____.\[ \text{Eu}^{3+}, \, \text{Lu}^{3+}, \, \text{Nd}^{3+}, \, \text{La}^{3+}, \, \text{Sm}^{3+} \]

Correct Answer: 2

Solution and Explanation

Top Questions on The Lanthanoids

Questions Asked in JEE Main exam

Number of colourless lanthanoid ions among the following is ____.
\[ \text{Eu}^{3+}, \, \text{Lu}^{3+}, \, \text{Nd}^{3+}, \, \text{La}^{3+}, \, \text{Sm}^{3+} \]