有下列五个化学方程式(X、Y、Z均为正值) ①C2H2(g)+H2(g)C2H4(g) ②CH4(g)H2(g)+1/2C2H4(g) ③C(s)+2H2(g)CH4(g);△H=-X kJ·mol-1 ④C(s)+1/2H2(g)1/2C2H2(g);△H=-Y kJ·mol-1 ⑤C(s)+H2(g)1/2C2H4(g);△H=-Z kJ·mol-1 当温度下降时①式平衡向右移动,②式平衡向左移动。据此判定③-⑤式中关于X、Y、Z的大小顺序排列正确的是 |
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A.X>Y>Z B.X>Z>Y C.Y>X>Z D.Z>X>Y |