By adding 20 ml of 0.1 N HCl to 20 ml 0.1 N KOH, the pH of the obtained solution will be

Options

A. 0
B. 7
C. 2
D. 9

Explanation

To solve the problem of finding the pH of the solution obtained by mixing 20 ml of 0.1 N HCl with 20 ml of 0.1 N KOH, we can follow these steps:

### Step-by-step Solution:

1. **Calculate the number of moles of HCl and KOH:**
- The normality (N) of both HCl and KOH is given as 0.1 N.
- Volume of HCl = 20 ml = 0.020 L
- Volume of KOH = 20 ml = 0.020 L
- Moles of HCl = Normality × Volume = 0.1 N × 0.020 L = 0.002 moles (or 2 millimoles)
- Moles of KOH = Normality × Volume = 0.1 N × 0.020 L = 0.002 moles (or 2 millimoles)

2. **Determine the reaction between HCl and KOH:**
- HCl (strong acid) reacts with KOH (strong base) in a neutralization reaction:
\[ \text{HCl} + \text{KOH} \rightarrow \text{KCl} + \text{H}_2\text{O} \]
- Since both reactants are present in equal moles (2 millimoles), they will completely neutralize each other.

3. **Identify the products of the reaction:**
- The products of the reaction are KCl (a neutral salt) and water.
- Since both HCl and KOH are strong electrolytes, they will completely dissociate in solution.

4. **Analyze the resulting solution:**
- After the neutralization, there are no excess H⁺ ions (from HCl) or OH⁻ ions (from KOH) remaining in the solution.
- The resulting solution consists of KCl and water.

5. **Determine the pH of the resulting solution:**
- The pH of a neutral solution (like pure water) is 7.
- Since KCl is a neutral salt and does not affect the pH, the pH of the resulting solution will also be 7.

### Final Answer:
The pH of the obtained solution will be **7**.