Chemistry - Atomic Structure Question with Solution | TestHub

$\sqrt{\ell (\ell +1)}h/2\pi =\sqrt{5}h/\pi =\sqrt{20}h/2\pi$, so $\ell (\ell +1)=20$ and $\ell =4$ (a g electron).

n must be greater than $\ell$, so n is at least 5.

Bohr angular momentum = $nh/(2\pi ):n=5$ gives $5h/(2\pi )$.

The other options correspond to $n=2$, 3 and 4, which are all below 5.

Answer: (D).