Respuesta :
I believe the answer is the last one; they are made of metals and non metal ions. Binary ionic compounds are ionic compounds that contain only two elements, one is the cation and the other is the anion. They are neutrally charged compounds made up of bonded ions, a cation an an anion. For example sodium chloride; contains Na+ (a cation with a +1) combines with Cl- (an anion with a -1 charge) to make sodium chloride.
Compounds with very different electronegativities AND metals and non metals.
