2.0 g of a metal burnt in oxygen gave 3.2 of its oxide. 1.42 g of the same metal heated in steam gave 2.27 g of its oxide. Which law is shown by this data?

Let M represent the mass of metal and O represent the mass of Oxygen.

In the first case, that is,

2.0 g of a metal burnt in oxygen gave 3.2 of its oxide.

$$\begin{gathered} RatioofM:O=2.0:3.2 \\ =0.625 \end{gathered}$$

In the second case, that is,

1.42 g of the same metal heated in steam gave 2.27 g of its oxide.

$$\begin{gathered} RatioofM:O=1.42:2.27 \\ =0.625 \end{gathered}$$

The ratio of the mass of metal and Oxygen is the same in both cases.

Hence, this data represents the “Law of Definite Proportions” or “Law of Constant Proportions" and it states that chemical compounds are made up of elements that are present in a fixed ratio by mass.