among halides of group 16 why hexafluoride are only stable halide
Hexafluoride are most stable because most of the group -16 element(except Oxygen) can achieve the maximum oxidation state of +6 in hexafluoride. Cl, Br and I dose not form the hexahalides because they does not bring about the contraction of d-orbital in central atom to bring about the better overlap of Central atom with halogens. So only hexafluorides of group-16 elements are well known.