Answer:
The K energy level or innermost shell of the electron.
Explanation:
The K shell is the innermost shell of an electron and to remove an electron in this shell, it requires the most energy compared to the other shells. An electron can be subdivided into K, L, M, N and so on shells depending on the number of electrons the element possesses. The amount of energy needed to remove electrons from each energy level increasing inwards and this is as a result of the shielding effects of the nucleus of the element. The nucleus shields electrons from been removed from the shells and the distance away from the nucleus by the electrons reduces their staying power. So electrons closer to the nucleus are not easily removed and requires the most energy in case it will be removed.
