Suppose that in any Bohr atom or ion, orbits are only in even numbers like 2, 4, 6, .... The maximum — Atomic Structure Chemistry Question

💡 Solution & Explanation

Visible region corresponds to the Balmer series, which ends at $n=2$. To emit maximum wavelength, the transition must be from the nearest permitted higher energy level. Since only even numbers are allowed, the transition is from $n=4$ to $n=2$. $\frac{1}{\lambda} = R\left(\frac{1}{2^2} - \frac{1}{4^2}\right) = R\left(\frac{1}{4} - \frac{1}{16}\right) = \frac{3R}{16}$. Thus, $\lambda = \frac{16}{3R}$. Therefore, correct answer is D.