In the Rutherford scattering experiment, the number of alpha particles scattered at an angle is 36 p — Atomic Structure Chemistry Question

💡 Solution & Explanation

The number of scattered particles $N(\theta) \propto \frac{1}{\sin^4(\theta/2)}$. For $60^\circ$, $N_{60} \propto \frac{1}{\sin^4(30^\circ)} = \frac{1}{(1/2)^4} = 16$. For $90^\circ$, $N_{90} \propto \frac{1}{\sin^4(45^\circ)} = \frac{1}{(1/\sqrt{2})^4} = 4$. So $N_{90} / N_{60} = 4 / 16 = 1/4$. Thus, $N_{90} = 36 / 4 = 9$. Therefore, correct answer is B.