Question

Assertion (A) The positively charged nucleus of an atom has a radius of almost $10^{-15}m$.
Reason (R) In $\alpha$-particle scattering experiment, the distance of closest approach for $\alpha$-particles is $\approx 10^{-15} m$.

• A. Both assertion and reason are true and reason is the correct explanation of assertion
• B. Both assertion and reason are true but reason is not the correct explanation of assertion
• C. Assertion is true but reason is false
• D. Both assertion and reason are false

Answer 1

Answer: (A)

In $\alpha$-particle scattering experiment, Rutherford found a small number of $\alpha$-particles which were scattered back through an angle approaching to $180^{\circ}$. This is possible only if the positive charges are connected at the centre or nucleus of the atom.