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?

Henry Moseley

The correct answer is option 3. Henry Moseley.

The scientist 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, is Henry Moseley.

Henry Moseley, an English physicist, conducted groundbreaking research on X-ray spectroscopy in the early 20th century. Through his experiments, Moseley discovered a relationship between the frequencies of X-rays emitted by different elements and their atomic numbers. He demonstrated that the X-ray spectra of elements were better ordered when plotted against atomic number (Z) rather than atomic mass. This work led to the modern understanding of the periodic table and the concept of atomic number as the fundamental property of an element.