The correct answer is neon
The formula unit of compounds formed depends on the valency of the combining ions.
The formula unit is the smallest unit of an ionic substance that gives us a picture of the ratio in which ions are combined in the ionic compound.
Usually, the formula unit is written based on the valency of the ions.
For the ions listed;
Li+ and 02- forms Li2O
Mg2+ and S2- forms MgS
A13+ and CI- forms AlCl3
Na+ and N3- forms Na3N
Learn more: brainly.com/question/9743981
B. It keeps the warm inside
