Question

The composition of sulphur trioxide is $40\%$ sulphur and $60\%$ oxygen. The composition of sulphur dioxide is $50\%$ sulphur and $50\%$ oxygen. This illustrates:

• A. Law of conservation of energy
• B. Law of multiple proportion
• C. Law of reciprocal proportion
• D. None of the above

Answer 1

The correct option is B Law of multiple proportion

Let us assume the amount of sulphur trioxide and sulphur dioxide be $100g$.

Therefore, mass of sulphur in sulphur trioxide = $40g$
Mass of oxygen in sulphur trioxide = $60g$

Similarly, mass of sulphur in sulphur dioxide = $50g$
mass of oxygen in sulphur dioixde $=50g$

Mass of $O$ that combines with $40g$ sulphur in
sulphur dioxide $=\frac{40\times 50}{50}$
= $40g$
In the question, the ratio of masses of $O$ that combines with the fixed mass of $S$, (40 g) is 60 : 40 or 3: 2 which is a whole number ratio. Hence this illustrates law of multiple proportions.