Which of the following solutions have different `pH`?
`100mL" of "0.2m" "HCl +100mL" of "0.4 M" "NH_(3)`
`50mL" of "0.1 M" HCl +"50mL" of "0.2 M NH_(3)`
`100 mL "of "0.3" M "HCl +100mL "of" 0.6 M NH_(3)`

Explanation

To determine which of the given solutions have different pH values, we will analyze each solution step by step.

### Step 1: Analyze the first solution
**Solution 1:** 100 mL of 0.2 M HCl + 100 mL of 0.4 M NH₃

1. Calculate the millimoles of HCl:
\[
\text{Millimoles of HCl} = \text{Molarity} \times \text{Volume} = 0.2 \, \text{mol/L} \times 100 \, \text{mL} = 20 \, \text{mmol}
...