Write consequences of Lanthanoid contraction. Why Zr and Hf exhibit siumilar properties ?

Why Zr and Hf exhibit similar properties ?

Write any two consequences of lanthanoids contraction.

Why Zr and Hf show similar chemical properties ?

What are the main consequences of lanthanoid contraction ?

How does lanthanoid contraction affect the physical and chemical properties of the elements of lanthanoid series ?