A define amount of impure sample of `P_(4)O_(6)` is treated with `20 mL` of `XM KMnO_(4)` in acidic medium to produce `H_(3) PO_(4)` and `MnCl_(2). 20mL` of same `KMnO_(4)` on treatement with `0.2M FeSO_(4)` requires exctly `10 mL` of `FeSO_(4)` solution. What is amount of pure `P_(4) O_(6)`? If `1g` sample is taken calculate `%` purity of `P_(4)O_(6)`.
