Question

Which among the following salts forms basic solution when dissolved in water?

• A. $NaNO_3$
• B. $CH_3COONH_4$
• C. KCN
• D. $NH_4F$

Hint:

To quickly assess a salt, identify the cation (which comes from the base) and the anion (which comes from the acid). The "stronger" parent dictates the final pH. Strong base wins = basic. Strong acid wins = acidic.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The pH of a salt solution depends on salt hydrolysis. A salt formed from a Strong Base and a Weak Acid will produce a basic solution (pH > 7) because the anion undergoes hydrolysis to produce $OH^-$ ions.

Step 2: Formula Application:
Analyze the parent acid and base for each salt: - $NaNO_3$: NaOH (Strong) + $HNO_3$ (Strong) $\rightarrow$ Neutral. - $KCN$: KOH (Strong) + HCN (Weak) $\rightarrow$ Basic.

Step 3: Explanation:
When $KCN$ dissolves, the $CN^-$ ion reacts with water: $CN^- + H_2O \rightleftharpoons HCN + OH^-$. The generation of hydroxide ions makes the solution basic. $NH_4F$ is actually slightly acidic because $HF$ is a stronger acid than $NH_4OH$ is a base.

Step 4: Final Answer:
The salt that forms a basic solution is KCN.