If the mass of electron is doubled, the radius of first orbit of H-atom becomes approximately — Atomic Structure Chemistry Question

💡 Solution & Explanation

Radius is inversely proportional to mass ($r \propto \frac{1}{m}$). If mass is doubled, radius becomes half. New radius $= \frac{0.529}{2} = 0.2645 \approx 0.265$ Å. Therefore, correct answer is B.