Ответ:

Объяснение:

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

W(Na) = Ar(Na) *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%