Any compound that contains a metal ion and a polyatomic ion would work. Polyatomic ions are covalently bonded non-metals that have some overall charge. Examples of common polyatomic ions include OH⁻ (hydroxide), NH₄⁺ (ammonium), and NO₃⁻ (nitrate). So answers to this question can be something like KOH (potassium hydroxide), but really, anything works if it contains a metal ion and a polyatomic ion.
