Calculate pH of the following mixtures:
0.2 litre of 0.1 M NaOH and 0.4 litre of 0.1 M `C_2H_5COOH` `(k_a(C_2H_5COOH)=5.6` x `10^-6)`

Explanation

To calculate the pH of the mixture containing 0.2 liters of 0.1 M NaOH and 0.4 liters of 0.1 M propanoic acid (C2H5COOH), we will follow these steps:

### Step 1: Calculate moles of NaOH and propanoic acid
- **Moles of NaOH**:
\[ \text{Volume of NaOH} = 0.2 \, \text{L} \]
\[
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