Question

Knowing that the chemistry of lanthanoids $\left(Ln\right)$ is dominated by its $+3$ oxidation state, which of the following statements is incorrect?

• A. $Ln\left(III\right)$ hydroxides are mainly basic in character
• B. The ionic sizes of $Ln\left(III\right)$ decrease in general with increasing atomic number
• C. Because of the large size of the $Ln\left(III\right)$ ions the bonding in its compounds is predominantly ionic in character
• D. $Ln\left(III\right)$ compounds are generally colourless

Answer 1

Answer: (D)

$Ln\left(III\right)$ compounds are generally colourless

$Ln\left(III\right)$ compounds are coloured due to the $f-f$ transitions in the lanthanoids but the colour is fainter as compared to the $d-d$ transitions in transition metals.