The coordination number (CN) and oxidation state (OS) of Co in $[Co(C_2O_4)_3]^{3-}$ is ...........

CN 6 and OS +3 respectively

The correct answer is Option (2) → CN 6 and OS +3 respectively

Let's solve this step by step.

We are given the complex: [Co(C₂O₄)₃]³⁻

Determine the oxidation state (OS) of Co:

• Let the oxidation state of Co = x
• Oxalate ion (C₂O₄²⁻) has a charge of -2. There are 3 oxalate ions.
• Overall charge of complex = -3

$x + 3(-2) = -3$

$x - 6 = -3$

$x = +3$

✅ So, OS = +3

Determine the coordination number (CN):

• Oxalate (C₂O₄²⁻) is bidentate, meaning each ligand binds through 2 donor atoms.
• There are 3 oxalate ligands, so total coordination = 3 × 2 = 6

✅ So, CN = 6

Answer:
CN 6 and OS +3 respectively ✅