Ответ:
Mr (NaNO3) = Ar (Na) + Ar (N) + Ar (O) * 3 = 23 + 14 + 16 * 3 = 85
W (Na) = Ar (Na) / Mr (NaNO3) = 23 / 85 = 0.2706 = 27.06%
W (N) = Ar (N) / Mr (NaNO3) = 14 / 85 = 0.1647 = 16.47%
W (O) = (Ar (O) * 3) / Mr (NaNO3) = 48 / 85 = 0.5647 = 56.47%
Ответ: W (Na) = 27.06%; W (N) = 16.47%; W (O) = 56.47%