Final answer:
Al(OH)₃ and CaF₂ solubility is affected by the pH of their solutions because these compounds are salts of weak acids or bases which can react with changes in H+ concentration.
Step-by-step explanation:
The question is about how lowering the pH of a solution would affect the solubility of certain compounds. Compounds like Al(OH)₃ and CaF₂ are affected by pH because they are salts of weak acids or bases, which can interact with excess H+ or OH- ions in solution. For instance, Al(OH)₃ will become more soluble in acidic conditions (lower pH) because the excess H+ ions will react with the OH- ions, forming water and thereby shifting the equilibrium to form more Al3+ ions. Similarly, CaF₂ will also become more soluble in acidic conditions as the fluoride ions will form HF with excess H+, decreasing the concentration of F- and shifting the equilibrium to dissolve more solid.