Test for Fe2+ ion in salt using potassium hexacyanidoferrate(III) It's given in my book that $\ce{Fe^3+}$ ion reacts with potassium hexacyanidoferrate(III) to give brown colour.
$$\ce{Fe^3+ + [Fe(CN)6]^3- -&gt; Fe[Fe(CN)6]}$$
Both the reactants have the same oxidation states.

My question is, can I use the same test for $\ce{Fe^2+}$?

First, the hexacyanidoferrate(III) will oxidize $\ce{Fe^2+}$ to $\ce{Fe^3+}$ like this:
$$\ce{Fe^2+ + [Fe(CN)6]^3- -&gt; Fe^3+ + [Fe(CN)6]^4-}$$
Then the reaction will continue to give brown colour.
$\ce{Fe^2+}$ is oxidised to $\ce{Fe^3+}$ while $\ce{[Fe(CN)_6]^{3-}}$ is reduced to $\ce{[Fe(CN)_6]^{4-}}$. These then form the prussian blue precipitate.