Barium lies in the second group of the periodic table. Elements in this group have two valence shell electrons. These elements have a tendency to produce cations since it is easier to lose the two electrons than to gain six. Now, out of the options, chlorine forms an anion. It is an element from group 7, meaning it exhibits a valency of -1. Therefore, in order to bond with Barium, two Chlorine atoms will be needed. The second option is correct.
