Question

The trend of basicity of lanthanoid hydroxides:

• A. increases across the lanthanoid series
• B. decreases across the lanthanoid series
• C. first increases and then decreases
• D. first decreases and then increases

Answer 1

The correct option is B decreases across the lanthanoid series

On moving from left to right in the lanthanoid series, size of the elements decreases thereby increasing the polarising power of the cation thus covalent character of M—OH bond increases and hence the basicity of lanthanoid hydroxides decreases.