Which of the following statements about ionization energy is true? a. ionization energy is the amount of energy used to add an electron to an atom. b. elements toward the bottom of a group periodic table generally have higher ionization energies than elements at the top of the group. c. in a period, elements farther to the right generally have lower ionization energies than elements on the left. d. potassium has a lower ionization energy than sodium.

D. Potassium has a lower ionization energy than sodium

Ionization energy = amount of energy it takes for an atom to LOSE an electron (so A is proven wrong already)

Why B and C are wrong: Ionization energy increases the closer the electrons are to the nucleus, so ionization energy increases as you go up and to the right on your periodic table. I remember that Fluorine (top right element on periodic table that is not a noble gas, those guys are weird) has the highest ionization energy.