\( 20 \, \text{mL} \) of a solution of acetic acid required \( 28.4 \, \text{mL} \) of \( 0.1 \, \text{M} \) \( \mathrm{NaOH} \) for its neutralization. A solution \( (X) \) was prepared by mixing \( 20 \, \text{mL} \) of the above acetic acid and \( 14.2 \, \text{mL} \) of \( 0.1 \, \text{M} \) \( \mathrm{NaOH} \) solution. What is the \( \mathrm{pH} \) of the solution \( (X) \)? \( (\mathrm{p}K_a \) value of acetic acid is \( 4.75) \).
