Who conducted X-ray spectroscopic study of a large number of elements and showed that the frequency of X-rays emitted by an element is related to the atomic number, Z, rather than the atomic mass?

Explanation

Henry Moseley investigated characteristic X-ray spectra and showed the fundamental importance of atomic number. For a specified spectral series, √ν is approximately linear in Z after allowing for screening. This supported ordering the periodic table by atomic number rather than atomic weight.