Which of the following is a tridentate ligand?

Ethylenediamine $(en)$ is a:

Number of ambidentate ligands in a representative metal complex $[M(en)(SCN)_4]$ is $[en = \text{ethylenediamine}]$

$[NiCl_4]^{2-}$ and $[Ni(CN)_4]^{2-}$ show similarity in

The sum of the coordination number and the oxidation number of the metal $M$ in the complex $[M(en)_2(C_2O_4)]Cl$ (where $en$ is ethylenediamine) is:

The correct structure of ethylenediaminetetraacetic acid $(EDTA)$ is