What is the co-ordination number of metal in $[Fe(C_2O_4)_3]^{3-}$?

Six

The correct answer is Option (3) → Six
The ligand oxalate (C₂O₄²⁻) is a bidentate ligand, meaning it donates two donor atoms (two oxygen atoms) to the metal ion.

In the complex [Fe(C₂O₄)₃]³⁻:

• Number of oxalate ligands = 3

• Each oxalate ligand forms 2 coordinate bonds with Fe.

Total coordinate bonds with Fe
= 3 × 2
= 6

Therefore, the coordination number of iron is 6.