Which of the following would best be classified as an ionic solid? Mg(s) Br2(s) CO2(s) RbCl(s) SiC(s)

The best classified as an ionic solid among the given options is RbCl(s).

Here's why:

Ionic solids are composed of positive and negative ions held together by electrostatic forces. The key characteristic of ionic solids is that they contain ions.

1. Mg(s) - This is a metallic solid, not an ionic solid.
2. Br2(s) - This is a molecular solid, not an ionic solid.
3. CO2(s) - This is also a molecular solid, not an ionic solid.
4. RbCl(s) - This is an ionic solid. It is composed of Rb+ (Rubidium ions) and Cl- (Chloride ions).
5. SiC(s) - This is a network covalent solid, not an ionic solid.

So, RbCl(s) is the best answer.