Which of the following salts are alkaline in aqueous solutions?

Options

A. NaCN
B. `K_(4)[Fe(CN)_(6)]`
C. `CH_(3)CO_(2) Na`
D. `FeCl_(3)`

Answer

To determine which of the given salts are alkaline in aqueous solutions, we need to analyze each salt based on its dissociation in water and the nature of the resulting ions. Here’s a step-by-step solution:

### Step 1: Understand the Concept of Alkalinity
Alkaline solutions are produced when a salt dissociates in water to form a strong base. A strong base will typically dissociate completely in water to produce hydroxide ions (OH⁻).

### Step 2: Analyze Each Salt

1. **NaCN (Sodium Cyanide)**
- Dissociation: NaCN → Na⁺ + CN⁻
- Reaction with water: CN⁻ + H₂O ⇌ HCN + OH⁻
- Result: NaOH (strong base) is produced along with HCN (weak acid). Since NaOH is a strong base, NaCN produces an alkaline solution.

2. **K₄Fe(CN)₆ (Potassium Ferrocyanide)**
- Dissociation: K₄Fe(CN)₆ → 4K⁺ + Fe(CN)₆⁴⁻
- Reaction with water: Fe(CN)₆⁴⁻ + H₂O ⇌ HFe(CN)₆³⁻ + OH⁻
- Result: KOH (strong base) is produced along with HFe(CN)₆³⁻ (weak acid). Therefore, K₄Fe(CN)₆ also produces an alkaline solution.

3. **CH₃CO₂Na (Sodium Acetate)**
- Dissociation: CH₃CO₂Na → CH₃CO₂⁻ + Na⁺
- Reaction with water: CH₃CO₂⁻ + H₂O ⇌ CH₃COOH + OH⁻
- Result: NaOH (strong base) is produced along with CH₃COOH (weak acid). Thus, CH₃CO₂Na produces an alkaline solution.

4. **FeCl₃ (Iron(III) Chloride)**
- Dissociation: FeCl₃ → Fe³⁺ + 3Cl⁻
- Reaction with water: Fe³⁺ + H₂O ⇌ Fe(OH)₃ + H⁺
- Result: HCl (strong acid) is produced along with Fe(OH)₃ (weak base). Since a strong acid is produced, FeCl₃ does not produce an alkaline solution.

### Step 3: Conclusion
The salts that produce alkaline solutions in aqueous solutions are:
- NaCN
- K₄Fe(CN)₆
- CH₃CO₂Na

Thus, the correct options are 1 (NaCN), 2 (K₄Fe(CN)₆), and 3 (CH₃CO₂Na).

---