The formula (total valence electron/8) given for hybridization is applicable or not? if not find the limitations and solution for this with example.

It is difficult to find hybridization of complex ions with this formula. so it is easy to find by using below formula1/2{No:of valence electron in central atom+ Monovalent atom attached to central metal atom+anionic charge-cationic charge}

Example NH3

Central atom valence electron is 5

Monovalent Hydrogen atom is 3

cationic or anionic charge is 0

then 1/2(5+3)=4,which says NH3 is sp3 hybridized