Calculate the pH of a 2.0 × 10^-5 M solution of HOC₆H₅. (K_a = 1.6 × 10^-10) A) 6.94 B) 6.75 C) 7.06 D) 7.25 E) none of these

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The correct answer is A because the pH of a 2.0 × 10^-5 M solution of HOC₆H₅ can be calculated using the following equation:pH = -log[H+], where [H+] is the molar concentration of hydrogen ions in the solution.The equilibrium constant for the dissociation of HOC₆H₅ is given by:K_a = [H+][OC₆H₅-] / [HOC₆H₅]Substituting the given values into this equation, we get:1.6 × 10^-10 = [H+][OC₆H₅-] / [2.0 × 10^-5]Solving for [H+], we get:[H+] = 1.6 × 10^-10 * [2.0 × 10^-5] / [OC₆H₅-]Since the concentration of OC₆H₅- is not given, we cannot calculate the exact value of [H+]. However, we can estimate the pH of the solution by assuming that the concentration of OC₆H₅- is negligible compared to the concentration of HOC₆H₅. In this case, we get:[H+] ≈ 1.6 × 10^-10 * [2.0 × 10^-5] = 3.2 × 10^-15 MSubstituting this value into the equation for pH, we get:pH = -log(3.2 × 10^-15) = 6.94Therefore, the pH of a 2.0 × 10^-5 M solution of HOC₆H₅ is approximately 6.94.

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