Redox Reactions

When \(3.92 \mathrm{~g}\) of Mohr salt is dissolved in \(100 \mathrm{~mL}\) of water, and titrated against \(\mathrm{KMnO}_4\) solution, \(20 \mathrm{~mL}\) of this solution required \(18 \mathrm{~mL}\) of \(\mathrm{KMnO}_4\) for complete oxidation. The strength of \(\mathrm{KMnO}_4\) is:
[Molar mass of Mohr salt is \(392 \mathrm{~g} \mathrm{~mol}^{-1}\) and \(\mathrm{KMnO}_4\) is \(158 \mathrm{~g} \mathrm{~mol}^{-1}\)]