1/2 - 3/7 = 7/14 - 6/14 = 1/14
It would be MnSO4
The (II) lets you know it’s the form with a 2+ charge and Sulfate has a 2- charge
These will cancel out making it plain MnSO4
If it was manganese (iii) sulfide the answer would be Mn2(SO4)3
If a metal is less reactive than carbon, it can be extracted from its oxide by heating with carbon. The carbon displaces the metal from the compound, and removes the oxygen from the oxide. This leaves the metal.
