Assertion : E^ for Mn^ 3+ / Mn^ 2+ is more positive than Cr^ 3+ /...

It is known that the value of $E^{{}^{\circ}}$ becomes more negative down the series. As the chromium is present below in electrochemical series than $\mathrm{Mn}$, so $\mathrm{Mn}$ has more positive $E^{{}^{\circ}}$ value than $\mathrm{Cr}$. $$\begin{array}{ll}\mathrm{Mn} \rightarrow3 d⁵ 4 s², \mathrm{Mn}^{2+} \rightarrow3 d⁵ 4 s⁰ \\ \mathrm{Cr} \rightarrow3 d⁵ 4 s¹, \mathrm{Cr}^{2+} \rightarrow3 d⁴ 4 s⁰ \end{array}$$ For elimination of one electron from $\mathrm{Mn}^{2+}$, more energy is required due to its stable configuration. That is why third ionization energy of $\mathrm{Mn}$ is larger than $\mathrm{Cr}$.