`pH` of a mixture containing `0.10 M X^(-)` and `0.20 M HX` is: `[pK_(b)(X^(-))=4]`

Options

A. `4+log2`
B. `4-log2`
C. `10+log2`
D. `10-log2`

Explanation

To find the pH of the mixture containing 0.10 M \(X^-\) and 0.20 M \(HX\), we can use the Henderson-Hasselbalch equation, which is applicable for buffer solutions. Here are the steps to solve the problem:

### Step 1: Identify the components
We have:
- \(HX\) (weak acid) with a concentration of 0.20 M
- \(X^-\) (conjugate base) with a concentration of 0.10 M
- Given \(pK_b\) of \(X^-\) is 4.

...