The dissociation constant of weak acid `HA` is `4.9xx10^(-8)`. After making the necessary approximations, calculate `pH` in `0.1 M` acid.

Explanation

To solve the problem of calculating the pH of a 0.1 M solution of the weak acid HA with a dissociation constant (K_a) of 4.9 x 10^(-8), we can follow these steps:

### Step 1: Write the dissociation equation
The dissociation of the weak acid HA can be represented as:
\[ HA \rightleftharpoons H^+ + A^- \]

### Step 2: Write the expression for the dissociation constant (K_a)
The dissociation constant (K_a) for the weak acid is given by:
...