Question

Of the following elements, which one has the lowest first ionization energy?
boron carbon aluminum silicon

Answer 1

Not absolutely correct in the short order but enough to make a guess depending on limited information. You should be familiar with this at the latest after your first college chemistry course.

Answer 2

Answer:

Boron

Explanation:

Because it has a complete 2s orbital and therefore, an increased shielding of the 2s orbital will reduce the ionisation energy.