(a) $[\mathrm{Fe}(\mathrm{CN})_6]^{3}$ - hexacyanoferrate (III) ion hybridization $-d^{2} s p^{3}$(b) Ambidentate ligand can bond through different atoms to form different coordination compounds. e.g. $\mathrm{NO}_2^{-}$can bind to the central atom or ion at either the nitrogen atom or one of the oxygen atom. Chelating ligand : If the ligands with two or more electron donor groups positioned in such a way that they form five or six membered ring with central metal ion are called chelating ligands. e.g. ethane -1, 2-diamine (en)