The magnitude of the change in oxidising power of the MnO_4^- / Mn^2+ couple is x × 10^-4 V, if the H^+ concentration is decreased from 1 M to 10^-4…

The magnitude of the change in oxidising power of the $\displaystyle \mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+}$ couple is $\displaystyle x \times 10^{-4} \mathrm{~V}$, if the $\displaystyle \mathrm{H}^{+}$ concentration is decreased from $\displaystyle 1$ M to $\displaystyle 10^{-4} \mathrm{M}$ at $\displaystyle 25$°C. (Assume concentration of $\displaystyle \mathrm{MnO}_4^{-}$ and $\displaystyle \mathrm{Mn}^{2+}$ to be same on change in $\displaystyle \mathrm{H}^{+}$ concentration). The value of $\displaystyle x$ is \_\_\_\_. (Rounded off to the nearest integer) $$\left[\text { Given }: \frac{2.303 \mathrm{RT}}{\mathrm{~F}}=0.059\right] $$