Respuesta :
Answer: Option (b) is the correct answer.
Explanation:
According to Afbau's principle, an electron enters the orbital with lowest energy first and subsequent electrons are fed in the order of increasing energies.
Copper is the element which has atomic number 29. It is a transition metal and atomic number of an atom determines the number of electrons present in an atom.
So, the stable electronic configuration of copper is as follows.
[tex]1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{10}[/tex].