1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution The lower the Ksp, the more insoluble. Therefore, I chose B since strontium and barium carbonates have the lowest Ksp. However, the question asks which carbonate will precipitate and I know that all carbonates are insoluble. Can someone explain to me what did I think wrong? Cheers!