1) Mr(SO2) = Ar(S) + 2*Ar(O) = 32 + 16*2 = 64
ω(Fe) = Ar(S) / Mr(SO2) * 100% = 32 / 64 *100% = 50%
ω(O) = 2*Ar(O) / Mr(SO2) * 100% = 32 / 64 *100% = 50%
2) Mr(KClO3) = Ar(K) + Ar(Cl) + 3*Ar(O) = 39 + 35.5 + 3*16 = 122.5
ω(K) = Ar(K) / Mr(KClO3) * 100% = 39 / 122.5 * 100% = 31.8%
ω(Cl) = Ar(Cl) / Mr(KClO3) * 100% = 35.5 / 122.5 * 100% = 29%
ω(O) = 3*Ar(O) / Mr(KClO3) * 100% = 48 / 122.5 * 100% = 392%