To form a word, say the word, 'to', you need one 't' and one 'o'. If you don't have exactly these two letters, you cannot form the word 'to'. Similarly, Dalton's theory said that chemical compounds are formed from an exact combination of atoms.

Just like 1 't' and 1 'o' combine to form one 'to', \(1 \, \mathrm{gm}\) of Hydrogen and \(8 \, \mathrm{gm}\) of Oxygen combine to form \(9 \, \mathrm{gm}\) of Water.
If we combine \(3 \, \mathrm{gm}\) of Hydrogen and \(8 \, \mathrm{gm}\) of Oxygen, what do we get?
  • \(9 \, \mathrm{gm}\) of Water only
  • \(18 \, \mathrm{gm}\) of Water only
  • \(9 \, \mathrm{gm}\) of Water and \(2 \, \mathrm{gm}\) of Hydrogen
  • Nothing