The oxidation state of chromium in the final product formed by reaction between KI and acidified potassium dichromate solution is

The reaction is:

${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7+7{\mathrm{H}}_2{\mathrm{SO}}_4+6\mathrm{KI}\to {\mathrm{Cr}}_2{\left({\mathrm{SO}}_4\right)}_3+7{\mathrm{H}}_2\mathrm{O}+3{\mathrm{I}}_2+4{\mathrm{K}}_2{\mathrm{SO}}_4$

Cr in Cr₂(SO₄)₃ is +3 oxidation state.

$$\begin{gathered} 2\left(\mathrm{Oxidation} \mathrm{state} \mathrm{of} \mathrm{Cr}\right)+3(\mathrm{oxidation} \mathrm{state} \mathrm{of} {\mathrm{SO}}_4^{3-})=0 \\ 2\left(\mathrm{Oxidation} \mathrm{state} \mathrm{of} \mathrm{Cr}\right)+3(-2)=0 \\ \mathrm{Oxidation} \mathrm{state} \mathrm{of} \mathrm{Cr}=+3 \end{gathered}$$