（2013山东莱芜）一定质量的镁条在氧气中完全燃烧后生成氧化镁，固体质量随时间的变化关系如图所示。下列说法不正确的是
A．生成MgO的质量：m2g
B．参加反应的Mg的质量：m1g
C．参加反应的O2的质量：（m2﹣m1）g
D．参加反应的镁和氧气的质量比＝
答案：D
题目分析：A、由图象可知反应的最后固体质量最终为m2g，该值即是氧化镁的质量；B、该反应的起初固体的质量即为镁的质量，所以为m1 g，C、由于氧化镁的质量等于镁和参加反应的氧气的质量和，所以参加反应的02的质量：(m2 -m1 ) g ；D、由镁的燃烧的方程式为2 Mg +O2点燃 2MgO可知镁和氧气的质量比为2×24/16×2，利用BC的结论可知镁和氧气的质量比=
，故选D。
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| Jack: Was the concert good? Sadie: (1) ___________________ Jack: Why are you angry then? (2) ___________________ Sadie: Well, after the concert I waited outside the theatre-in the rain. I wanted their autographs. Jack: Did you see them? Sadie: (3) ___________________ Jack: Did they talk to you? Sadie: No, they didn't. They didn't wave. They didn't smile. They didn't say hello. (4) ___________________ They just jumped into a big, black car and then disappeared. Jack: (5) ___________________ Sadie: Yes. But that was yesterday.
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