H₂S contains 97 .11% sulphur; 

SO₂ contains 50% oxygen and H₂O contains 11 .11% hydrogen. Thus, it follows;

H₂S: 5.89 g H combines with :94.11 g S 

Hence,1 g H combines with = 16 gS

SO₂ : 50 g O combine with = 50 gS

Hence, 1 g O combines with = 1 gS

H₂O : 11.11 g H combines with = 88.89 g O

1 g H combine with = 8 g O

In the two compounds H₂S and H₂O, the weights of S and O that combines with the fixed weight of 1g. of H are with ratio of 16:8 or 2:1 (Ratio 1)

In SO₂, the ratio of weight of S and O is 1:1 (Ratio II)

Ratio (I) and (II) $\frac{2}{1}$ and $\frac{1}{1}$ are 2:1 and this is in accordance  with the  law  of reciprocal proportion.