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

Explanation

The consequences of lanthanoid contraction are as follows:
i) Lanthanoid contraction helps in the separation of lanthanoids due to difference in their atomic or ionic radii. ii ) Due to lanthanoid contraction, the basic strength of oxides and hydroxides decreases in the series. iii) Due to lanthanoid contraction the elements of 4d and 5d series have similarity in atomic radii. iv) Lanthanoid contraction results in steady increase in the standard reduction potentials `(E^@)` .