What are the oxidation numbers for these elements?

S in H2So3


S in MgSo4


and S in K2S....





My answers were 3-,4+, and 2-, but I don't know if they are right. so if someone wants to figure them out and see if i got them wrong, i'd be grate-full. oh' and if i did, can u explain why.What are the oxidation numbers for these elements?
My answers were:


S in H2SO3 is 4+





S in MgSO4 is 6+





and S in K2S is 2-





For the first one, hydrogen has an oxidation number of 1+ per atom. There are 2 hydrogen atoms in that compound so the overall charge of hydrogen is 2+. The oxidation number of oxygen is 2- per atom, and having 3 atoms of oxygen the overall charge of oxygen is 6- so combine the charges. +2+-6 is equal to -4 which is the combined charge of hydrogen and oxygen, and you know that all compounds have to be neutral in charge (charge of 0), so add +4 to -4 to get 0, which tells you that sulfur has an oxidation number of 4+


Do the same thing for the rest and you will figure it out =)What are the oxidation numbers for these elements?
H2SO3, S=+4,


becuase H=+1, O=-2, S has to be +4 so +2(H)+4(S)-6(O)=0





MgSO4, S=+6,


becasue Mg=+1, +2+6-8=0





The last one is correct