Practice question

Given: The K_a of chloroacetic acid is 1.35 × 10⁻³. What is the pH of a 0.05 M solution? These values define the system as per NCERT data. Formula: K_a = x²/0.05, 1.35 × 10⁻³= x²/0.05, x² = 6.75 × 10⁻⁵. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: x = sqrt6.75 × 10⁻⁵ approx 8.22 × 10⁻³, pH = -log(8.22 × 10⁻³) approx 2.09 . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.