Which of the following best describes how further studies supported Joseph Proust's discovery about proportion of elements in water?

Max Planck discovered the Planck's constant.

John Dalton proposed that matter is made of tiny particles.

James Chadwick discovered neutral particles in the nucleus of the atom.

Niels Bohr determined that electrons inhabit distinct energy levels.

Answer is: John Dalton proposed that matter is made of tiny particles.

Proust's law or law of constant composition said that a given chemical compound always contains its component elements in fixed ratio and does not depend on method of preparation.

Water (H₂O) is made of two hydrogen atoms and one oxygen atom:

m (H) : m (O) = 2·1 : 16 = 1: 8.

Dalton said that matter is composed of atoms and atoms of different elements can join to form chemical compound.