What is the coordination number of $Fe$ in $[Fe(CO)_5]$ and $[Fe(C_2O_4)_3]^{3-}$ respectively?

5 and 6

The correct answer is Option (4) → 5 and 6

1. [Fe(CO)₅]

• CO is a monodentate ligand → donates 1 pair of electrons.
• There are 5 CO ligands.

Coordination number = 5

2. [Fe(C₂O₄)₃]³⁻

• C₂O₄²⁻ (oxalate) is a bidentate ligand → donates 2 pairs.
• There are 3 oxalate ligands.

Coordination number = 3 × 2 = 6