Which postulate of Dalton's Atomic Theory was proven wrong by the discovery of subatomic particles?

The correct option is: Matter consists of indivisible atoms.

Explanation:

John Dalton proposed his Atomic Theory in 1808, which laid the foundation for modern chemistry. One of the main postulates of his theory was that matter is made up of extremely small, indivisible particles called atoms (which cannot be divided or destroyed).

However, towards the late 19th and early 20th centuries, scientists discovered subatomic particles inside the atom:

1. Electrons (discovered by J.J. Thomson in 1897)

2. Protons (discovered by Ernest Rutherford / E. Goldstein)

3. Neutrons (discovered by James Chadwick in 1932)

The discovery of these subatomic particles proved that an atom is not indivisible, but rather composed of even smaller fundamental particles. Therefore, the postulate stating that "Matter consists of indivisible atoms" was proven to be incorrect.