Zr(Z=40) and Hf(Z=72) have similar atomic and ionic radii because of:

Zr and Hf have same atomic and ionic radii because

Zr and Hf have almost equal atomic and ionic radii because of (a) lanthanoid contraction (b) diagonal relationship (c) actinoid contraction (d) belonging to the same group

Why do Zr(Z = 40) and Hf(Z = 72) have comparable atomic radii ?

How would you account for the following? (l) Transition metals exhibit variable oxidation states. (ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii. (iii) Transition metals and their compounds act as catalyst.