Chapter 31 - Atomic Physics - Problems and Conceptual Exercises - Page 1113: 34

a) greater than b) I

(a) We know that the de Broglie wavelength of an electron in $n=2$. The Bohr orbit of hydrogen is greater than the de Broglie wavelength of an electron in the $n=1$ Bohr orbit of hydrogen. (b) We know that the best explanation is option (I) -- that is, the de Broglie wavelength in the nth state is $\frac{2\pi}{rh}$, where $r$ is proportional to $n_2$. Therefore, the wavelength increases with increasing $n$, and is greater for $n=2$ than $n=1$.