Ответ 1)―А, 2)―Г, 3)―Б, 4)―В
1) m(Mg):m(O)=Ar(Mg):Ar(O)=24:16=3:2
2) m(H):m(S):m(O)=2•Ar(H):Ar(S):4•Ar(O)=2•1:32:4•16=2:32:64=1:16:32
3) m(Fe):m(O)=2•Ar(Fe):3•Ar(O)=2•56:3•16=112:48=7:3
4) m(Cu):m(S):m(O)=Ar(Cu):Ar(S):4•Ar(O)=64:32:4•16=64:32:64=2:1:2