Final answer:
Among the given options, NH₄Br (ammonium bromide) is the salt that will form an acidic solution upon dissolving in water. It will form an acidic solution because ammonium is the conjugate acid of the weak base ammonia. The correct option is (B)
Step-by-step explanation:
To determine which of these salts will form an acidic solution upon dissolving in water, we need to assess the acid-base properties of the constituent ions of each salt. This assessment is based on whether the cation is derived from a weak base, and whether the anion is derived from a weak acid.
KOH (potassium hydroxide) is not a salt but a strong base, so it's out of the running. NH₄Br (ammonium bromide), however, will form an acidic solution because NH₄⁺ (ammonium) is the conjugate acid of NH₃ (ammonia), which is a weak base. When NH₄⁺ dissolves in water, it can release H⁺ ions, making the solution acidic.
NaCN (sodium cyanide) is derived from the reaction of a weak acid (hydrocyanic acid) and a strong base (sodium hydroxide), so its solution will be basic, not acidic. Similarly, LiBr (lithium bromide) is a salt that is derived from a strong acid (hydrobromic acid) and a strong base (lithium hydroxide), hence, it forms a neutral solution.
In conclusion, among the given options, NH₄Br is the salt that will form an acidic solution when dissolved in water.