A student performed an investigation into the solubility of compounds containing the polyatomic ion sulfite (SO32-) and recorded the data shown above. Which of the following solubility rules would be supported by this data? The majority of sulfite compounds are insoluble with the metals of group 2 being exceptions to this rule. Sulfite compounds are typically insoluble, but alkali metals are an exception to this. Most sulfite compounds are soluble with the only exceptions being compounds of Sr+2 and Ca+2 cations. All sulfite compounds are insoluble, and this student made an experimental error.