Answer
The first ionization energy and nuclear charge are directly proportional.
Work Step by Step
The first ionization energy and nuclear charge are directly proportional.
As the nuclear charge increases, valence electrons are tightly held towards the nucleus and it is difficult to remove the valence electron and hence ionization energy increases.
Similarly, as the nuclear charge decreases, the valence electrons are loosely held by the nucleus and it is easy to remove the valence electron and hence ionization energy decreases.
