Question 7
Why does the first ionization energy decrease as you go down a group?
The right answer is the one marked above.
Going down a group, the number of energy levels increases. The outermost electrons are therefore further from the nucleus, the attraction on them is weaker, and removing one is easier — so less energy is needed.
The proton count actually rises going down a group, not falls. It is the extra distance that wins out: the outer electrons are further away, and that matters more than the extra positive charge in the nucleus.