Chemistry - Carbonyl compounds Question with Solution | TestHub

${\mathrm{C}}_2{\mathrm{O}}_4^{2-}$is a symmetrical bidentate ligand so it can be used for chelate complex formation.
Pyridine,$\mathrm{N}{\mathrm{H}}_2-\stackrel{+}{\mathrm{N}}{\mathrm{H}}_3$are monodentate ligands so can not form chelate complex.
$\mathrm{S}\mathrm{C}{\mathrm{N}}^{-}$is an ambidentate ligand so only one site can be used at a time so no chelate complex is possible.