Question

Cu Kα radiation of wavelength 1.5418 A˚, is generated by which of the following transition?

(a) 1s→2p

(b) 3s→1s

(c) 2s→4s

(d) 2p→1s

This question was addressed to me by my school principal while I was bunking the class.

My doubt stems from Sources of Background Radiation Fluorescence in chapter X-Ray Diffraction of Solid State Chemistry

Answer 1

Correct choice is (d) 2p→1s

To explain I would say: 2p→1s electronic transition generates the Cu Kα radiation of wavelength 1.5418 A˚ and in order to create a vacant 1slevel in the first place, 1s→∞ ionization potential is needed and this energy difference corresponds to a wavelength for copper of1.3804 A˚.