Ответ:

Объяснение:

1)

Mr(K2SО4) = Ar(K) * 2 +  Ar(S) + Ar(O) * 4= 39 * 2 + 32+ 16 * 4 = 174г/моль

w(K) = m(K2)/Mr(K2SO4)  * 100% = 78/174 *100% = 44,8%  

w(S) = m(S)/Mr(K2SO4)  * 100% = 32/174 *100% = 18,4%  

w(O)= (m(O4) : Mr(K2SO4)) * 100% = 64/174* 100% = 36,8%

2)

Mr(H3PO4) = Ar(H) *3 + Ar(P) +Ar(O) *4 = 3 + 31 + 16 * 4 = 98 г/моль

w(Н) = m(Н3)/Mr(Н3РО4)  * 100% = 3/98 *100% = 3%  

w(Р) = m(Р)/Mr(Н3РO4)  * 100% = 31/98 *100% = 31,6%  

w(O)= (m(O4) : Mr(Н3РО4)) * 100% = 64/98* 100% = 65,4%

3)

Mr(КCl) = Ar(K) + Ar(Cl) = 39 + 35 = 74 г/моль

w(K) = m(K)/Mr(KCl)  * 100% = 39/74 *100% = 52,7%  

w(Cl) = m(Cl)/Mr(KCl)  * 100% = 35/74 *100% = 47,3%