What is the formula of following coordination compound:

Potassium trioxalatoaluminate(III)

$K_3[Al(C_2O_4)_3]$

The correct answer is Option (1) → $K_3[Al(C_2O_4)_3]$

Core Concept:

Oxalate ($C_2O_4^{2-}$) is a bidentate ligand with $-2$ charge. Aluminium is in $+3$ oxidation state.

Stepwise Calculation:

Let charge on complex $= x$

$Al^{3+} + 3(C_2O_4)^{2-}$

$= +3 + 3(-2)$

$= +3 - 6$

$= -3$

So complex ion $= [Al(C_2O_4)_3]^{3-}$.

To neutralise:

$3 K^+$ needed.

Final formula $= K_3[Al(C_2O_4)_3]$.