Fantastic! \(9 \, \mathrm{gm}\) of water contains only \(1 \, \mathrm{gm}\) of Hydrogen. So, we cannot get \(2 \, \mathrm{gm}\) of Hydrogen from it.
We have two laws: the Law of Conservation of Mass, and the Law of Constant Proportions. These are observations of how Nature behaves. But, we need to explain why Nature behaves like this.

John Dalton came up with one explanation. He said that all matter was composed of extremely tiny particles called Atoms. These atoms were indivisible. They had their own mass and couldn't be created or destroyed.
According to Dalton's theory, could we take a Hydrogen atom and convert it to an Oxygen atom?
  • Yes
  • No