Solve this following
Question:

On complete reaction of $\mathrm{FeCl}_{3}$ with oxalic acid in aqueous solution containing $\mathrm{KOH}$, resulted in the formation of product A. The secondary valency of Fe in the product $A$ is

(Round off to the Nearest Integer).

Solution:

$\mathrm{Fe}^{3+}+3 \mathrm{~K}^{+}+3 \mathrm{C}_{2} \mathrm{O}_{4}{ }^{2-} \rightarrow \mathrm{K}_{3}\left[\mathrm{Fe}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]$

Secondary valency of $\mathrm{Fe}$ in ‘ $\mathrm{A}^{\prime}$ is 6 .