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's behavior when dissolved in water. Alkaline solutions have a pH greater than 7, indicating they are basic. Let's evaluate each salt one by one.

### Step-by-Step Solution:

1. **Identify the Salts**:
We have the following salts to analyze:
- Option 1: NaCN
- Option 2: K4[Fe(CN)6]
- Option 3: CH3COONa
- Option 4: FeCl3

2. **Analyze Option 1: NaCN**:
- When NaCN is dissolved in water, it dissociates into Na⁺ and CN⁻ ions.
- CN⁻ is the conjugate base of the weak acid HCN.
- The presence of CN⁻ will react with water to produce OH⁻ ions (hydroxide ions), making the solution basic.
- Therefore, the pH will be greater than 7, indicating that NaCN is alkaline.

3. **Analyze Option 2: K4[Fe(CN)6]**:
- When K4[Fe(CN)6] is dissolved in water, it dissociates into K⁺ and [Fe(CN)6]⁴⁻ ions.
- The [Fe(CN)6]⁴⁻ ion does not produce any acidic protons and can lead to the formation of hydroxide ions.
- Hence, the solution will also have a pH greater than 7, making K4[Fe(CN)6] alkaline.

4. **Analyze Option 3: CH3COONa**:
- When CH3COONa is dissolved in water, it dissociates into CH3COO⁻ and Na⁺ ions.
- CH3COO⁻ is the conjugate base of the weak acid acetic acid (CH3COOH).
- The CH3COO⁻ ion will react with water to produce OH⁻ ions, resulting in a basic solution.
- Therefore, the pH will be greater than 7, indicating that CH3COONa is alkaline.

5. **Analyze Option 4: FeCl3**:
- When FeCl3 is dissolved in water, it dissociates into Fe³⁺ and Cl⁻ ions.
- Fe³⁺ can hydrolyze to form Fe(OH)₃ (a weak base) and H⁺ ions, leading to an acidic solution.
- Since the solution has a pH less than 7, FeCl3 is not alkaline.

### Conclusion:
The salts that are alkaline in aqueous solution are:
- Option 1: NaCN
- Option 2: K4[Fe(CN)6]
- Option 3: CH3COONa

**Final Answer**: Option 1, Option 2, and Option 3 are alkaline in aqueous solutions.

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