Question

Which of the following is the strongest acid?

• A. $HClO$
• B. $HCl{O}_3$
• C. $HCl{O}_4$
• D. $HCl{O}_2$

Answer 1

The correct option is C

$HCl{O}_4$

More the % oxygen content, more the acidic nature.
The charge stabilization of oxyacids of chlorine increases in the order:
${ClO}^{-}$<${Cl{O}_2}^{-}$ < ${Cl{O}_3}^{-}$ < $Cl{O}_4^{-}$

which signifies that ${ClO}^{-}$ will have minimum stability and therefore, will have maximum attraction for $H^{+}$. Thus, ${ClO}^{-}$ will be strongest base and so its conjugate acid HClO will be the weakest acid. Similarly, in this series ${Cl{O}_4}^{-}$ is the weakest base (maximum stabilized) and its conjugate acid $HCl{O}_4$ is the strongest acid.