Although zirconium belongs to 4d transition series and hafnium to 5d transition series even then they show similar physical and chemical properties because............. .

1. Both belong to d-block

2. Both have same number of electrons

3. Both have similar atomic radius

4. Both belong to the same group of the Periodic Table

Due to lanthanoide contraction, Zr and Hf possess nearly same atomic and ionic radii ie. Zr = 160 pm and Hf = 159 pm, Zr4+ = 79 pm and Hf4+ = 78 pm. Therefore, these two elements show similar properties (physical and chemical properties).