Question

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

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

Answer 1

Answer: (B)

Due to poor shielding effect of $f$ subshell ionic radius of $Ln ^{-3}$ decreases as atomic number increases. If an element has unpaired electron then it shows colour. lanthanum are basic in nature Their' s compounds are predominantly ionic due to large size of cation.