Question

which energy level requires the most energy to remove an electron?

Answer 1

The innermost shell because it has the lowest distance from the nucleus and the level of energy of electron depends directly on the nucleus charge and depends inversely on the distance from the charge. Therefore, here charge on nucleus remaining same distance is lowest on innermost shell.

Answer 2

The innermost shell.
because it has the lowest distance from the nucleus and the level of energy of electron depends directly on the nucleus charge and depends inversely on the distance from the charge.Therefore, here charge on nucleus remaining same distance is lowest on innermost shell.