The lanthanide contraction is responsible for the fact that

Options

A. Zr and Yt have about the same radius
B. Zr and Nb have smaller oxidation state
C. Zr and Hf have about the same radius
D. Zr and Zn have the same oxidation state.

Answer

C

Explanation

The elements of second and third transiation series resembles more in properties than the elements of first and second transition series. It is due to lanthanide contraction. So, due to lanthanide contraction Zr and Hf have the same radius and also known as twins.