Assertion : $E_{\mathrm{OP}\left(\mathrm{H}_2 \mathrm{O}_2\right)}^{\mathrm{o}}=-1.77 \mathrm{~V}$ (in acidic medium) and $E_{\mathrm{OP}\left(\mathrm{H}_2 \mathrm{O}_2\right)}^{\mathrm{o}}=-0.87 \mathrm{~V}$ (in alkaline medium). Reason : $\mathrm{H}_2 \mathrm{O}_2$ is more powerful oxidant in alkaline medium.

• A

  If both assertion and reason are true and reason is the correct explanation of assertion.
• B

  If both assertion and reason are true but reason is not the correct explanation of assertion.
• Correct answer
  C

  If assertion is true but reason is false.
• D

  If both assertion and reason are false.

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