Which of the following salts will give highest pH in water ?

Options

A. `CuSO_(4)`
B. `KCl`
C. `Na_(2)CO_(3)`
D. `NaCl`

Answer

To determine which of the given salts will yield the highest pH in water, we need to analyze the nature of each salt and the acids and bases from which they are derived.

### Step-by-Step Solution:

1. **Identify the Salts and Their Components**:
- **CuSO4 (Copper Sulfate)**: Derived from copper hydroxide (Cu(OH)2, a weak base) and sulfuric acid (H2SO4, a strong acid).
- **KCl (Potassium Chloride)**: Derived from potassium hydroxide (KOH, a strong base) and hydrochloric acid (HCl, a strong acid).
- **Na2CO3 (Sodium Carbonate)**: Derived from sodium hydroxide (NaOH, a strong base) and carbonic acid (H2CO3, a weak acid).
- **NaCl (Sodium Chloride)**: Derived from sodium hydroxide (NaOH, a strong base) and hydrochloric acid (HCl, a strong acid).

2. **Determine the pH of Each Salt**:
- **CuSO4**: Since it comes from a strong acid (H2SO4) and a weak base (Cu(OH)2), it will produce an acidic solution with a pH < 7.
- **KCl**: This salt is formed from a strong acid (HCl) and a strong base (KOH), resulting in a neutral solution with a pH = 7.
- **Na2CO3**: This salt comes from a strong base (NaOH) and a weak acid (H2CO3). The strong base dominates, leading to a basic solution with a pH > 7.
- **NaCl**: Similar to KCl, it is formed from a strong acid (HCl) and a strong base (NaOH), resulting in a neutral solution with a pH = 7.

3. **Compare the pH Values**:
- CuSO4: pH < 7 (acidic)
- KCl: pH = 7 (neutral)
- Na2CO3: pH > 7 (basic)
- NaCl: pH = 7 (neutral)

4. **Conclusion**:
Among the salts analyzed, Na2CO3 will give the highest pH in water because it is derived from a strong base (NaOH) and a weak acid (H2CO3), resulting in a basic solution.

### Final Answer:
The salt that will give the highest pH in water is **Na2CO3** (Sodium Carbonate).

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