A healthy person weighing 50kg contains 2g iron.

Purple no longer exists, which proves that the reflection is complete, that is, FeSO4 is completely oxidized.

This 12ml should be zero. How many moles of potassium permanganate are there at this time?

Then the mass of iron is calculated by ion equation.

2(Mn7+)+ 10(Fe2+)= 10(Fe3+)+2(Mn2+)