Ответ:

Объяснение:

Mr(K2S) = Ar(K) * 2 + Ar(S) = 39 * 2 + 32 = 110г/моль

w(S) = m(S)/Mr(K2S)  * 100% = 32/110 *100% = 29,1%  

Mr(H2SO4) = 2Ar(H) + Ar(S) + 4Ar(O) = 2 * 1 + 32 + 4 * 16 = 98 г/моль

w(S) = m(S)/Mr(H2SO4) * 100% = 32/98 * 100% = 32,6%

Mr(Fe2(SO4)3 = 2Ar(Fe) + 3(Ar(S) + 4Ar(O)) =  56 * 2 + 3 * (32 + 16 * 4) = 112 + 3 * 96 = 400 г/моль

w(S) = m(S)/Mr(Fe2(SO4)3) * 100% = 32/400 * 100% = 8%

Mr(SO3) = Ar(S) + Ar(O) * 3 = 32 + 16 * 3 = 80 г/моль

w(S) = m(S)/Mr(SO3) * 100% = 32/80 *100% = 40%