Assertion: A future discovery of subatomic particles led to the failure of Dalton’s atomic theory.
Reason: An atom is made up of electrons, protons and neutrons
Assertion and reason are correct, and Reason is the correct explanation
One of the postulates of Dalton's atomic theory was that 'atoms are indivisible and indestructible'. A future discovery of sub atomic particles led to the failure of Dalton’s atomic theory as an atom can be further subdivided into electrons, protons and neutrons