2．0.5 mol CH4完全燃烧生成CO2和液态H2O时，放出445 kJ的热量，则下列热化学方程式中正确的是( )
A．CH4(g)＋2O2(g)===CO2(g)＋2H2O(g)
ΔH＝－890 kJ·mol－1
B．CH4(g)＋2O2(g)===CO2(g)＋2H2O(l)
ΔH＝＋890 kJ·mol－1
C．CH4(g)＋2O2(g)= ==CO2(g)＋2H2O(l)
ΔH＝－890 kJ·mol－1
D.CH4(g)＋O2(g)===CO2(g)＋H2O(l)
ΔH＝－890 kJ·mol－1
解析：A项，水的状态为液态，应标注“l”，错误；B项，该反应放热，焓变的符号应为“－”，错误；D项，焓变的数值与化学计量数不对应，错误。
答案：C
