Pyrolusite is the main ore of manganese in which it is present asIts 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)Qsample containing MnO_(2)is treated with HCl liberating Cl_(2) The Cl_(2) is passed into a solution of KI and 30cm^(3) ofhypo is required to titrate the liberated iodine. What is the percentage of MnO_(2) in the sample ?