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Answer the following.
Though Zr (Z = 40) belongs to 4d transition series and Hf (Z = 72) belongs to 5d transition series…
Though $\text{Zr}$ ($Z = 40$) belongs to 4d transition series and $\text{Hf}$ ($Z = 72$) belongs to 5d transition series, yet the two cannot be separated easily.
Answer
Answer
Because of lanthanoid contraction: the poor shielding by $4f$ electrons makes the radius of Hf almost equal to that of Zr, so their chemical properties are very similar.