题干

化学反应N2 + 3H2 ="==" 2NH3的能量变化如图所示,以下叙述正确的是

A:1/2 mol N2和3/2 mol H2转变为原子是放出能量a KJ

B:1mol N 和3mol H结合成1mol NH3(g)时放出热量b KJ

C:1mol NH3(l)转变为1mol NH3(g)时放出热量 c KJ 

D:1/2 mol N2和3/2 mol H2反应生成1mol NH3(l)是吸热反应

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B

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