The first ionization energy (KJ/mol) for each group one element are shown

Question

3 Li 520
11 Na 496
19 K 419
37 Rb 403
55 Cs 376

Which statement explains the trend in first ionization energy of group 1 elements?

As a number of valence electrons increases, the amount of energy required to add electron to the atom decreases.
As the number of valence electrons increases, the amount of energy required to remove an electron from the atom decreases.
As the distance between the nucleus and the outermost electrons increases, the amount of energy required to add an electron to the atom decreases.
As the distance between the nucleus and the outermost electrons increases, the amount of energy required to remove an electron from the atom decreases.

Answer 1

As the number of valence electrons increases, the amount of energy required to remove an electron from the atom decreases. This is evidenced by the trend in first ionization energy for group 1 elements, where the ionization energy decreases as you move down the group and the number of valence electrons increases.