Multiple choice Which of the following compounds represents hypochlorous acid? HClO2 HClO HClO3 HClO4 Reveal answer Fill a bubble to check yourself B Correct answer Explanation Hypochlorous acid is HClO. The 'hypo-' prefix indicates one fewer oxygen than chlorous acid (HClO2). Chloric acid is HClO3 and perchloric acid is HClO4.