The radius of the second orbit of H-atom is equal to the radius of — Atomic Structure Chemistry Question

💡 Solution & Explanation

Radius $r \propto \frac{n^2}{Z}$. For H second orbit, $n=2, Z=1$, so $r \propto \frac{2^2}{1} = 4$. For Be$^{3+}$ fourth orbit, $n=4, Z=4$, so $r \propto \frac{4^2}{4} = 4$. The radii are equal. Therefore, correct answer is D.