Question: why hclo4 is stronger than hclo3?
Answer: HClO4 (perchloric acid) is a stronger acid than HClO3 (chloric acid). ... Both HClO4 and HClO3 are oxyacids of chlorine, and the oxidation number of chlorine in them are +7 and +5 respectively. Higher the oxidation number stronger will be the acid, for the oxyacids of a particular element.