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①CH4(g)+2O2(g) =CO2(g)+2H2O(1) △H=+890.3 kJ/mol
②CH4(g)+2O2(g) =CO2(g)+2H2O(1) △H=-890.3 kJ/mol
③CH4(g)+2O2(g) =CO2(g)+2H2O(g) △H=-890. 3 kJ/mol
④2H2(g)+O2(g)= 2H2O(1) △H=- 571.6 kJ/mol
| A．仅有②④ | B．仅有② | C．仅有②③④ | D．全部 |
同类型试题
y = sin x， x∈R， y∈[–1，1]，周期为2π，函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x， x∈[–1，1]， y∈[–π/2，π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
y = sin x， x∈R， y∈[–1，1]，周期为2π，函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x， x∈[–1，1]， y∈[–π/2，π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
