Chemistry - Salt Analysis Question with Solution | TestHub

Paragraph: The reaction of ${\mathrm{K}}_3\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$ with freshly prepared ${\mathrm{FeSO}}_4$ solution produces a dark blue precipitate called Turnbull's blue. Reaction of ${\mathrm{K}}_4\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$ with the ${\mathrm{FeSO}}_4$ solution in complete absence of air produces a white precipitate $\mathbf{X}$, which turns blue in air. Mixing the ${\mathrm{FeSO}}_4$ solution with ${\mathrm{NaNO}}_3$, followed by a slow addition of concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ through the side of the test tube produces a brown ring.