1. The problem statement, all variables and given/known data Number 12. Ignore the scribbling and the circled answers. http://i.minus.com/i17OAHo9PELaW.jpg [Broken] 2. Relevant equations The periodic table trend of acid/base behavior says that oxides of elements on the right of the periodic table will behave as acids in water. It says that oxides of elements on the left of the periodic table will behave as bases in water (metal hydroxides). 3. The attempt at a solution I know that SO3 and P4O10 will dissolve in water to form a strong and weak acid, respectively. The metal oxide MgO will form a metal hydroxide. However, I'm not sure what happens to Bi2O3. It's definitely on the right side of the periodic table, so I would expect it to form an acid. However, according to Wikipedia, it is insoluble in water. We were not taught exceptions in class (at least to the periodic trend of acid/base behavior). What would your take be on this question?