pH and Solubility Practice Test

The solubility stays the same because changing pH affects only the rate of dissolving, not the equilibrium solubility.

The solubility increases because $\text{H}^+$ reacts with $\text{F}^-$ to form HF, lowering $[\text{F}^-]$ and shifting dissolution toward products.

The solubility stays the same because fluoride is the conjugate base of a strong acid and therefore cannot react with $\text{H}^+$.

The solubility decreases because strong acids always decrease the solubility of ionic solids by increasing ionic strength.

The solubility decreases because $\text{H}^+$ is a common ion with $\text{CaF}_2$ and suppresses dissolution by the common-ion effect.