JEE Chemistry 2025 Question with Solution

Given: The reaction is

Find: The number of optical isomers shown by complex $A$.

From the reaction, the complex formed is potassium ferrioxalate:

So the coordination entity is

This is of the type

where $AA$ is a symmetrical bidentate ligand, here oxalate $(C_2O_4)^{2-}$.

Such octahedral $[M(AA)_3]$ complexes are chiral and exist as two non-superimposable mirror images, the $\Delta$ and $\Lambda$ forms.

Therefore, the number of optical isomers is $2$.

Given: The product formed from $FeCl_3$, $KOH$, and $H_2C_2O_4$ is an iron oxalate complex.

Find: How many optical isomers it exhibits.

The reaction forms potassium ferrioxalate:

In $[Fe(C_2O_4)_3]^{3-}$, each oxalate ligand is bidentate, so three oxalate ligands occupy all six coordination positions around iron.

Hence the complex belongs to the octahedral $[M(AA)_3]$ category. This category shows optical isomerism because the ligand arrangement has no plane of symmetry.

So there are exactly two enantiomeric forms:

• $\Delta$ form
• $\Lambda$ form

Therefore, the required numerical answer is $2$.