The acidic strength of oxoacids of the same central element increases with its increasing oxidation — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

As the number of highly electronegative Oxygen atoms increases, the oxidation state of the central Chlorine atom increases (+1, +3, +5, +7). This greatly increases the effective electronegativity of Chlorine, pulling electron density away from the O-H bond, weakening it, and making the release of an $H^+$ ion much easier.