Which of the following salts will give highest pH in water
(a)KCl
(b)NaCl
(c)`Na_2CO_3`
(d)All of these

Options

A. KCl
B. NaCl
C. `Na_2CO_3`
D. All of these

Answer

To determine which of the given salts will give the highest pH in water, we need to analyze each salt based on its acidic and basic properties.

### Step-by-Step Solution:

1. **Identify the Nature of Each Salt:**
- (a) **KCl**: This salt is formed from potassium hydroxide (KOH), a strong base, and hydrochloric acid (HCl), a strong acid. Therefore, KCl is a neutral salt.
- (b) **NaCl**: This salt is formed from sodium hydroxide (NaOH), a strong base, and hydrochloric acid (HCl), a strong acid. Thus, NaCl is also a neutral salt.
- (c) **Na₂CO₃**: This salt is formed from sodium hydroxide (NaOH), a strong base, and carbonic acid (H₂CO₃), which is a weak acid. Therefore, Na₂CO₃ is a basic salt.

2. **Determine the pH of Each Salt in Water:**
- Neutral salts (KCl and NaCl) do not undergo hydrolysis and will have a pH close to 7 when dissolved in water.
- Basic salts (Na₂CO₃) will undergo hydrolysis, leading to the formation of hydroxide ions (OH⁻), which will increase the pH above 7.

3. **Hydrolysis of Sodium Carbonate (Na₂CO₃):**
- When Na₂CO₃ dissolves in water, it dissociates into sodium ions (Na⁺) and carbonate ions (CO₃²⁻).
- The carbonate ion (CO₃²⁻) can react with water:
\[ \text{CO}_3^{2-} + \text{H}_2\text{O} \rightleftharpoons \text{HCO}_3^{-} + \text{OH}^- \]
- This reaction produces hydroxide ions (OH⁻), which increases the pH of the solution.

4. **Conclusion:**
- Among the options given, Na₂CO₃ will produce the highest pH in water due to its basic nature and the hydrolysis reaction that occurs.

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

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