At 298 K, the enthalpy change (in kJ ) for the reaction given below is $\mathrm{CH}_4(g)+\mathrm{O}_2(g) \rightarrow \mathrm{C}(s)+2 \mathrm{H}_2 \mathrm{O}(l)$ (Given): $\mathrm{H}_2(g)+\frac{1}{2} \mathrm{O}_2(g) \rightarrow \mathrm{H}_2 \mathrm{O}(l) ; \Delta H^{\ominus}=-286 \mathrm{~kJ}$ $\mathrm{C}(s)+\mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g) ; \Delta H^{\ominus}=-394 \mathrm{~kJ}$ $\mathrm{CH}_4(g)+2 \mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g)+2 \mathrm{H}_2 \mathrm{O}(l) ; \Delta H^{\ominus}=-890 \mathrm{~kJ}$

• A

  $+496$
• Correct answer
  B

  $-496$
• C

  $-1284$
• D

  $+680$

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