Which of the following compounds would have an increase in solubility when placed into an acidic solution? 

• A. CaBr₂
• B. NaI
• C. KCN
• D. LiNO₃
• E. Hg₂Br₂

Answer: (C)

Verified step by step guidance

1. Identify the nature of each compound and whether its solubility is affected by changes in pH, particularly acidic conditions.
2. Recognize that compounds containing anions that can react with H+ ions (from acid) may have increased solubility due to the removal of the anion by protonation.
3. Analyze each compound: CaBr\_2 and NaI contain halide ions (Br\^- and I\^-), which are the conjugate bases of strong acids and do not react significantly with H+; thus, their solubility is not increased in acid.
4. KCN contains the cyanide ion (CN\^-), which is the conjugate base of a weak acid (HCN). In acidic solution, CN\^- reacts with H+ to form HCN, reducing CN\^- concentration and shifting the dissolution equilibrium to dissolve more KCN, increasing its solubility.
5. LiNO\_3 and Hg\_2Br\_2 do not have anions that react with H+ in a way that increases solubility; LiNO\_3 is highly soluble and unaffected by pH, and Hg\_2Br\_2 is a sparingly soluble salt without acid-base reactive ions.