Pyrolusite is the main ore of manganese in which it is present as Its Mn content is determined by reducing it under acidic condition to `Mn^(2+)` with the help of oxalate `(C_(2)O_(4)^(2-))` ion which in turn gets oxidized to `CO_(2)` The analytical determination is carried out by adding a known excess volume of `(C_(2)O_(4)^(2-))` solution to a suspension of the pyrolusite and digesting the mixture on a hot water bath until all the `MnO_(2)` has been reduced. The excess unreacted oxalate solution is then titrated with standardized `KMnO_(4)` solution. Thereby Mn content of ore can be calculated. `KMnO_(4)`solution is also standardized under acidic condition against oxalate ion wherein `MnO_(4)^(-)` ion is reduced to `Mn^(2+)` and `(C_(2)O_(4)^(2-))` ion is oxidized to `CO_(2)`
Q What is the percentage of pure `MnO_(2)` in the above question ?

Options

A. `50.9%`
B. `62.5%`
C. `59.4%`
D. `75.4%`

Answer

C

Explanation

Amount of ferrous ammounium sulphate reacted with pyrolusite`(MnO_(2)=20-3.92=16.08g`
or number of equivalent of `MnO_(2)=(16.08)/(392)=0,041`
`implies x=1.781 therefore %purity=1.781/3xx100=59.4%`