Question

Which of the following will be more soluble in an acidic solution than in pure water?

RbClO4, Cul, PbSO4,CuCN,Ni(OH)2

Answer 1

the salts that will be more soluble in an acidic solution than in pure water will be those that contain basic anions

accordingly your answer will be

Ni(OH)2 , CuCN

CuI , PbSO4 , & RbClO4

have I- , (SO4)-2 , & (ClO4)-1 ions

which are weak conjugate bases of the stron acids: HI, H2SO4, & HClO4

those ions will not react with the addition of H+ ion

nor will H+ ion combine with them

however Ni(OH)2 , CuCN both release ions which will react with H+ OH- & CN- aere strong conjugate bases of the

weak acids H2O & HCN, H+ will combine with those ions thus by removing them from solution,