What are ambidentate ligands? Give an example.

Among the following which are ambidentate ligands

(1) ${{\mathrm{NO}}_2}^{-}$

(2)${\mathrm{C}}_2{{\mathrm{O}}_4}^{2-}$

(3) ${\mathrm{EDTA}}^{4-}$

(4) ${\mathrm{SCN}}^{-}$

Explain the term Ligand.

The sum of coordination number and oxidation number of metal $\mathrm{M}$ in the complex $\left[\mathrm{M}{\left(\mathrm{e}\mathrm{n}\right)}_2\left({\mathrm{C}}_2{\mathrm{O}}_4\right)\right]\mathrm{C}\mathrm{l}$ (Where en is ethylenediamine) is: