Question

Assertion: The discovery of sub-atomic particles led to the failure of Dalton’s atomic theory.
Reason: An atom is made up of protons, neutrons and electrons.

• A. Assertion and reason are correct, but reason is not the correct explanation.
• B. Both assertion and reason are correct, and reason is the correct explanation.
• C. Assertion and reason, both are wrong.
• D. Assertion is wrong, but the reason is correct.

Answer 1

The correct option is B Both assertion and reason are correct, and reason is the correct explanation.

$\bullet$ One of the postulates of Dalton's atomic theory states that 'atoms are indivisible and indestructible'.

$\bullet$ The discovery of sub-atomic particles led to the failure of Dalton’s atomic theory as an atom can be further subdivided into protons, neutrons and electrons.

$\bullet$ Hence, both assertion and reason are correct and reason is the correct explanation of assertion.