Answer;
-Chlorine
Explanation;
-A monatomic ion is an ion consisting of exactly one atom. If it has more than one atom, then it is called polyatomic. If it has two atoms it is diatomic, three atoms, it is triatomic, and so forth.
-Potassium, sulfur and Xenon are all examples of monoatomic ions.
-Chlorine on the other hand is diatomic, meaning, it has two atoms, and that is why its formula is Cl2. Chlorine is a molecular compound in group 7, each of its molecule has two atoms.
