(i) From the E° values for $\mathrm{Mn}^{3+}/\mathrm{Mn}^{2+}$ for Cr, Mn and Fe, it is veryclear that $\mathrm{Fe}^{3+}$ is more stable than $\mathrm{Mn}^{3+}$ in an acidic medium, whereas lessstable than Cr3+ because of the higher reduction potential in comparison to$\mathrm{Cr}^{3+}/\mathrm{Cr}^{2+}$ and lower reduction potential than $\mathrm{Mn}^{3+}/\mathrm{Mn}^{2+}$.(ii) Reduction potential for $\mathrm{Mn}^{3+}/\mathrm{Mn}$ is most negative and therefore,it will be most easily oxidised and ease of getting oxidised will be$\mathrm{Mn} > \mathrm{Cr} > \mathrm{Fe}$.