Answer
These results are consistent with the law of multiple proportions.
Work Step by Step
In sulphur dioxide : mass of $O_{2}$ per gram of sulphur = 3.49/3.50 $\approx$ 1
In sulphur trioxide : mass of $O_{2}$ per gram of sulphur = 6.75/4.50 = 1.5
Ratio of mass of $O_{2}$ per gram of sulphur in sulphur trioxide and sulphur dioxide = 1.5 / 1 = 3 : 2 ,
which is a ratio of small whole numbers.
Thus, these results are consistent with the law of multiple proportions
