Aqueous solution having highest pH is

Options

A. `0.1 M NH_4CL`
B. `0.1 M NaCL`
C. `0.1 M (NH_4)_2 SO_4`
D. `0.1 M CH_3COONa`

Answer

To determine which aqueous solution has the highest pH, we need to understand the relationship between pH and the nature of the solution. Here’s a step-by-step solution:

### Step 1: Understand pH
pH is a measure of the acidity or basicity of a solution. A pH of 7 is considered neutral, values below 7 indicate acidity, and values above 7 indicate basicity. Therefore, a higher pH corresponds to a more basic solution.

**Hint:** Remember that pH is inversely related to the concentration of hydrogen ions (H⁺) in the solution.

### Step 2: Identify the Nature of Solutions
To achieve a high pH, we need a solution that is basic. Basic solutions are typically formed from strong bases or salts derived from strong bases and weak acids.

**Hint:** Strong bases increase the concentration of hydroxide ions (OH⁻), which raises the pH.

### Step 3: Analyze the Given Options
We need to consider the salts provided in the options. A salt formed from a strong base and a weak acid will yield a basic solution.

1. **NH₄Cl**: NH₄⁺ comes from NH₃ (a weak base) and Cl⁻ comes from HCl (a strong acid). This will not yield a basic solution.
2. **NaCl**: Na⁺ comes from NaOH (a strong base) and Cl⁻ comes from HCl (a strong acid). This is neutral.
3. **KNO₃**: K⁺ comes from KOH (a strong base) and NO₃⁻ comes from HNO₃ (a strong acid). This is also neutral.
4. **Na₂CO₃**: Na⁺ comes from NaOH (a strong base) and CO₃²⁻ comes from H₂CO₃ (a weak acid). This will yield a basic solution.

**Hint:** Look for the combination of a strong base with a weak acid to find a basic solution.

### Step 4: Conclusion
Among the options, Na₂CO₃ is the salt that will produce the highest pH when dissolved in water because it is derived from a strong base (NaOH) and a weak acid (H₂CO₃).

**Final Answer:** The aqueous solution having the highest pH is **Na₂CO₃**.