Q3(a). Reading a weak-acid titration curve

The titration curve for a weak acid vs. strong base (NaOH) has the following shape [titration curve given in the paper]. (i) Identify the weak acid: I. CH₃COOH (Ka = 1.69 × 10⁻⁵) II. HCN (Ka = 5 × 10⁻¹⁰) III. Benzoic acid (Ka = 6.3 × 10⁻⁵) IV. Pyridinium ion (Ka = 5.9 × 10⁻⁶). (ii) Explain the process and species involved in the regions marked as (1), (2), (3) and (4) that contribute to the pH at near regions.