The correct order of acidity of the following compounds is

• A

  $\mathrm{HOCl} \lt \mathrm{HClO}_2 \lt \mathrm{HClO}_4 \approx \mathrm{HIO}_4$
• Correct answer
  B

  $\mathrm{HOCl} \lt \mathrm{HClO}_2 \lt \mathrm{HIO}_4 \lt \mathrm{HClO}_4$
• C

  $\mathrm{HIO}_4 \approx \mathrm{HClO}_4 \lt \mathrm{HClO}_2 \lt \mathrm{HOCl}$
• D

  $\mathrm{HOCl} \lt \mathrm{HClO}_2 \lt \mathrm{HClO}_4 \lt \mathrm{HIO}_4$

Hence, the correct answer is option: 'B'.