A.2CH 4 (g)+4O 2 (g)===2CO 2 (g)+4H 2 O(l) Δ H =+890 kJ·mol - 1 B.CH 4 (g)+2O 2 (g)===CO 2 (g)+2H 2 O(l) Δ H =+890 kJ·mol - 1 C.CH 4 (g)+2O 2 (g)===CO 2 (g)+2H 2 O(l) Δ H =-890 kJ·mol - 1 D.1/2CH 4 (g)+O 2 (g)===1/2CO 2 (g)+H 2 O(l) Δ H =-890 kJ·mol - 1