Which of the following oxo acid of sulphur has O-O bond?

• A

  $\mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_7$
• Correct answer
  B

  $\mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_8$
• C

  $\mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_6$
• D

  $\mathrm{H}_2 \overline{\mathrm{S}}_2 \mathrm{O}_5$

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