How do we differentiate between $\mathrm{Fe}^{3+}$ and $\mathrm{Cr}^{3+}$ in group III?
How do we differentiate between $\mathrm{Fe}^{3+}$ and $\mathrm{Cr}^{3+}$ in group III?
by taking excess of $\mathrm{NH}_4 \mathrm{OH}$ solution
by increasing $\mathrm{NH}_4{ }^{+}$ion concentration
by decreasing $\mathrm{OH}^{-}$ion concentration
both (b) and (c)
Solution
$\mathrm{NH}_4^{+}$ions are increased to suppress release of $\mathrm{OH}$ ions, hence solubility product of $\mathrm{Fe}(\mathrm{OH})_3$ is attained. Colour of precipitate is different.