Question

Which of the following statements is correct about the stability of the complexes of lanthanoids?

• A. Stability of complexes increases as the size of lanthanoid decreases.
• B. Stability of complexes decreases as the size of lanthanoid decreases.
• C. Lanthanoids do not form complexes.
• D. All the complexes of lanthanoids have same stability.

Answer 1

The correct option is A Stability of complexes increases as the size of lanthanoid decreases.

As the size of lanthanoid decreases, stability of complexes increases because (i) as size $\downarrow$es, covalent character increases (ii) $La\to Lu$, size $\downarrow$es stability of oxo salts also decreases (iii) stability of complexes increases.