Question

Zr and Hf have almost equal atomic and ionic radii because of:

• A. diagonal relationship.
• B. lanthanoid contraction.
• C. actinoid contraction.
• D. belonging to the same group.

Answer 1

The correct option is B lanthanoid contraction.

This is because of poor screening effect by 4f electrons,which lead to the lanthanoid contraction.Hence,is the reason of $Zn$ and $Hf$ have almost equal atomic size.