3) Mr(HNO₃) = 1 * 1 + 1 * 14 + 3 * 16 = 63

ω(H) = 1 * 1 / 63 = 0.02 или 2%

ω(N) = 1 * 14 / 63 = 0.22 или 22%

ω(O) = 3 * 16 / 63 = 0.76 или 76%

4) Mr(MnSO₄) = 1 * 55 + 1 * 32 + 4 * 16 = 151

ω(Mn) = 1 * 55 / 151 = 0.36 или 36%

ω(S) = 1 * 32 / 151 = 0.22 или 22%

ω(O) = 4 * 16 / 151 = 0.42 или 42%

5) Mr(K₂SO₄) = 2 * 39 + 1 * 32 + 4 * 16 = 174

ω(K) = 2 * 39 / 174 = 0.45 или 45%

ω(S) = 1 * 32 / 174 = 0.18 или 18%

ω(O) = 4 * 16 / 174 = 0.37 или 37%

6) Mr(FeSO₄) = 1 * 56 + 1 * 32 + 4 * 16 = 152

ω(Fe) = 1 * 56 / 152 = 0.37 или 37%

ω(S) = 1 * 32 / 152 = 0.21 или 21%

ω(O) = 4 * 16 / 152 = 0.42 или 42%

7) Mr(Fe₂(SO₄)₃) = 2 * 56 + 3 * 32 + 12 * 16 = 400

ω(Fe) = 2 * 56 / 400 = 0.28 или 28%

ω(S) = 3 * 32 / 400 = 0.24 или 24%

ω(O) = 12 * 16 / 400 = 0.48 или 48%

8) Mr(H₃PO₄) = 3 * 1 + 1 * 31 + 4 * 16 = 98

ω(H) = 3 * 1 / 98 = 0.03 или 3%

ω(P) = 1 * 31 / 98 = 0.32 или 32%

ω(O) = 4 * 16 / 98 = 0.65 или 65%

9) Mr(CuSO₄) = 1 * 64 + 1 * 32 + 4 * 16 = 160

ω(Cu) = 1 * 64 / 160 = 0.4 или 40%

ω(S) = 1 * 32 / 160 = 0.2 или 20%

ω(O) = 4 * 16 / 160 = 0.4 или 40%