Relative Solubilities of Salts in Acidic Solution I stumbled across this problem which I don't understand the answer to:
Which solid is much more soluble in 1 M $\ce{HCl}$ than in $\ce{H2O}$?
(A) $\ce{CaHPO_4}$
(B) $\ce{CaCl_2}$
(C) $\ce{BaBr2}$
(D) $\ce{BaSO4}$
Chloride, Bromide, and Sulfate all correspond to strong acids, while phosphate corresponds to a weak acid.  

With 1M H+ available, phosphate will be essentially fully protonated, while the others will still be anions.