Among the following, which element has the lowest ionization energy? question 2 options: cs na cl i

The element with the lowest ionization energy is CESIUM, CS.
Ionization energy is the energy required to remove the most loosely bound electron in an atom of an element. The higher the number of shells in an atom of an element, the lower the ionization energy that will be required to remove the valence electron.

Sorry i dont understand the question can you rephase it?