Acidity of oxyacids of chlorine decreases in the following order.
\(H \stackrel {+7}{C l} O_{4} > H \stackrel {+5}{C l}O_{3} > H \stackrel {+3}{C l}O_{2} > H\stackrel {+1}{C l}O\)
So relative acidic character increases.
$ClF _{3}, IF _{7}, BrF _{5^{2}}, BrF _{3}, I _{2} Cl _{6^{\prime}} IF _{5}, ClF , ClF _{5}$