What is the coordination number of central metal ion in $\left[\mathrm{Fe}\left(\mathrm{C}_2 \mathrm{O}_4\right)_3\right]^{3-}$ ?

What is EAN of Cu in $\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}$ ?

Find the total number of moles of donor atoms present in one mole trioxalatocobaltate(III) ion.

Identify the number of donor atoms in EDTA molecule that form coordinate bond with central metal atom or ion in a complex.