Which lead salt will increase in solubility when its saturated solution is acidified?

Question

Lead(II) fluoride(PbF2), lead(II) chloride(PbCl2), lead(II) bromide(PbBr2), or lead(II) iodide(PbI2).

*All of which are slightly soluble in water.

Answer 1

This is the same as asking - which of the halide ions is the strongest base? Or, indeed, which of the hydrohalic acids is the weakest? And the answer is HF.

F- + H2O <----> HF + OH-

Adding an acid will pull this equation to the right, thus reducing the concentration of F- ions, and increasing the solubility of PbF2.