Answer:
fourth shell to the second shell
Explanation:
When an electron of an atom moves from a lower energy shell to a higher energy shell (such as 1st shell to the 3rd shell), it absorbs energy through a specific wavelength of electromagnetic wave equivalent to the difference in energy levels of the electron shells.
Conversely, when the electron jumps from a higher electron shell to a lower one (such as in this case) it releases energy, in the form a specific wavelength of electromagnetic wave, equivalent to the difference in energy levels between the two electron shells.
