# Electron Capture - Moseley's law - Calculating frequency

Suppose $Hg(A=197)$ decays to $Au(A=197)$ by electron capture and assume that electron is captured from $K$-shell and an x-ray is emitted. Is the electron captured from $Hg$ or $Au$? I am confused in using the Mosley's equation. Shall I use $Z=79$ or $80$.