Question

Chemistry of lanthanides ($ \text{Ln} $) is dominated by +3 oxidation state. Which of the following is incorrect?

• A. \( \text{Ln} (III) \) compounds are generally colourless
• B. Ionic size of \( \text{Ln} (III) \) decreases with increasing atomic number
• C. Due to large size of \( \text{Ln} (III) \) ions, the bonding in their compounds is ionic
• D. \( \text{Ln} (III) \) hydroxides are basic in character

Hint:

Lanthanides in the +3 oxidation state are typically coloured due to electron transitions in their f-orbitals.

Answer 1

The Correct Option is A

The \( \text{Ln} (III) \) compounds are usually coloured due to f-electron transitions. Therefore, the statement that \( \text{Ln} (III) \) compounds are generally colourless is incorrect. Other statements are correct regarding the properties of lanthanides.