Question

10 g of an oxide of X contains 5.0 g of X while 8.0 g of another oxide of the same species contains 3.2 g of X. Which law is indicated in this data?

• A. Law of multiple proportions
• B. Law of conservation of mass
• C. Law of constant proportions
• D. Law of reciprocal proportions

Answer 1

The correct option is A Law of multiple proportions

In the 1st oxide, the amount of X = 5 g and the amount of oxygen = 5 g
In the 2nd oxide, the amount of X = 3.2 g and the amount of oxygen = 4.8 g
On fixing the mass of X at 5 g,
The amount of oxygen required in the 2nd oxide = $\frac{4.8}{3.2}\times 5=7.5\text{g}$
According to the law of multiple proportions, when we fix one element the other element will bear a simple ratio in both the compounds. Hence ratio of amount of oxygen used in both compounds is $5:7.5$ or $2:3$, hence illustrating the law.