Verified answer

Ответ:

Объяснение:

Mr(B2O3) = 11*2 + 16*3 = 70

W(B) = Ar(B) *n / Mr(B2O3)  *100% = 11*2 / 70  *100% = 31%

W(O) = Ar(O) *n / Mr(B2O3)  *100% = 16*3 / 70  *100% = 69%