The number of moles of KMnO4 that will be needed to react with one mole of sulphite ion in acidic solution is

2KMnO4 +  3H2SO4→ K2SO4+2MnSO4+3H2O+5OSO32−+O →  SO42− × 52KMnO4 +  3H2SO4 +5SO32− → K2SO4 or   +2MnSO4+3H2O+5SO42−2MnO4- +  6H++5SO32− →2Mn2+                                          +5SO42−+3H2O5  moles  of SO32−  required  2  moles  of  MnO4−1  moles  of SO32−  will  be  required  25  moles  of MnO4−