Abnormal Properties Of Hf

Abnormal Factors

Abnormal secretion of thyroxine produces

Cretinism is due to abnormal secretion of :

The properties of Zr and Hf are similar because

Why Zr and Hf or Nb and Ta exhibit similar properties? Or Zirconium (atomic number40) and hafnium number 72) occur together in minerals and they exhibit similar properties. Give reasons.