M(Mn(ClO3)3)=(54.938)+(35.45x3)+(15.999x9)
M(Mn(ClO3)3)=305.279 g/mol
Sulfur forms compounds in oxidation states −2 (sulfide, S2−), +4 (sulfite, SO32−), and +6 (sulfate, SO42−). I don't know what type of ion but hope this helps!! :)
Multiply amount in grams by the relative atomic mass of magnesium then multiply by avagodro constant (6.02*10^23)