A sample of pyrolusite `(MnO_2)` weighs 0.5 g. To its solution, 0.6674 g of `As_2O_3` and dilute, acid are added. After the reaction has ceased, arsenic `(As^(3+))` in `As_2O_3` is titrated with `45mL` of `(M)/(10)` `KMnO_4` solution. Calculate the percentage of `MnO_2` in pyrolusite. (Atomic weight of As is 74.9 and that of Mn is 55.)

Options

A. 0.6225
B. 0.68
C. 0.673
D. 0.666

Answer

A