On complete reaction of FeCl$$_3$$ with oxalic acid in aqueous solution containing KOH, resulted in the formation of product A. The secondary valency of Fe in the product A is ________. (Round off to the Nearest Integer).

When $$\text{FeCl}_3$$ reacts with oxalic acid ($$\text{H}_2\text{C}_2\text{O}_4$$) in the presence of KOH, the iron(III) forms a complex with oxalate ions. The oxalic acid is first neutralized by KOH to produce potassium oxalate, and then the oxalate ions coordinate with $$\text{Fe}^{3+}$$.

Iron(III) has a coordination number of 6 in most of its complexes. Each oxalate ion ($$\text{C}_2\text{O}_4^{2-}$$) is a bidentate ligand, occupying two coordination sites. Three oxalate ions therefore occupy all six coordination sites, forming the complex $$[\text{Fe}(\text{C}_2\text{O}_4)_3]^{3-}$$, which exists as the potassium salt $$\text{K}_3[\text{Fe}(\text{C}_2\text{O}_4)_3]$$.

In Werner's theory, the secondary valency corresponds to the coordination number — the number of ligand atoms directly bonded to the metal ion. Since three bidentate oxalate ligands contribute a total of 6 donor atoms around $$\text{Fe}^{3+}$$, the secondary valency is 6.

The answer is 6.