Which of the following cannot be circumference of an orbit in H-atom? ( = radius of the first orbit) — Atomic Structure Chemistry Question

💡 Solution & Explanation

Circumference $C = 2\pi r_n = 2\pi (r_0 n^2) = 2\pi r_0 n^2$. For integer $n=1$, $C=2\pi r_0$. For $n=2$, $C=8\pi r_0$. For $n=3$, $C=18\pi r_0$. $4\pi r_0$ would require $n^2=2$, which implies non-integer $n$, so it cannot be a valid circumference. Therefore, correct answer is B.