Ответ:

Объяснение: Mr(NaHCO3) = 23 + 1 + 12 + 16*3 =84

W(Na) = Ar(Nа) *n / Mr(NaHCO3)  *100% = 23 *1 / 84  *100% = 27%

W(H) = Ar(H) *n / Mr(NaHCO3)  *100% = 1*1 / 84  *100% = 1 %

W(C) = Ar(C) *n / Mr(NaHCO3)  *100% = 12 *1 / 84  *100% = 14%

W(O) = Ar(O) *n / Mr(NaHCO3)  *100% = 16*3 / 84  *100% = 58%

Вроде