将12g镁在一定量的氧气中燃烧，有如下数据：第一次第二次第三_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题问答题

将12g镁在一定量的氧气中燃烧，有如下数据：

	第一次	第二次	第三次
所给氧气的质量/g	4	8	16
生成氧化镁的质量/g	10	20	20

（1）一次实验中，所给物质恰好完全反应的是______．

（2）第三次实验剩余的物质是______．

（3）第一次生成10g氧化镁而不是16g氧化镁的原因是______．

答案

（1）根据化学方程式：2Mg+O₂

点燃

.

2MgO可知，每48份质量的镁和32份质量的氧气完全反应生成80份质量的氧化镁，所以第二次实验中12g镁在8g氧气恰好完全反应生成氧化镁的质量为20g；故填：第二次；

（2）根据（1）信息可知12g镁和8g氧气恰好完全反应，而第三次实验氧气的质量为16g，所以氧气会剩余；故填：氧气；

（3）根据（1）信息可知4g氧气能和6g镁恰好完全反应，所以当12g镁和4g氧气发生化学反应时，氧气完全反应，镁有剩余（12g-6g=6g），所以生成氧化镁的质量为4g+6g=10g．故填：12g镁和4g氧气发生化学反应时，氧气完全反应，镁剩余6g．

完形填空

The train shakes back and forth, its wheels making a loud noise against the tracks. Outside the window the freezing cold of winter rules. The carriage is filled with cold, ___1___ passengers.
Suddenly a little boy ___2___ his way through the grown-up legs and sits down by the window. He is all alone among the ___3___ grown-ups. What a brave child, I think. His father ___4___ very strange happens suddenly. The ___5___ little boy slides down from his seat and leans his hand on my knee. ___6___, I think that he wants to ___7___ me and return to his father, so I help him to stand up. But instead he leans forward and holds his ___8___ up towards mine. He wants to say something to me, I think. I lower my head to receive the ___9___. Wrong again! What I do receive is a ___10___ kiss on the cheek.
The boy calmly returns to his seat, leans back and continues looking out of the window. I am ___11___. What just happened? A child is kissing ___12___ grown-ups on the train. How can anybody want to kiss such a man that has so much beard? Soon enough, all of my neighbors are certainly ___13___. Nervous and a little surprised, we ___14___ at the father. When he sees our questioning ___15___ as he gets ready for his stop, he offers a clue(线索).
“He’s so happy to be alive,” the father says. “He has been very sick.”
Father and son ___16___ into the crowd moving toward the exit. The doors close and the train goes on. On my cheek I can still ___17___ the child’s kiss—a kiss that has triggered(触发) some soul-search inside me. How many ___18___ kissing each other from the joy of being alive? How many even give much thought to the privilege(特权)of ___19___?
The little kisser had taught us a sweet but serious lesson: Be careful you don’t let yourself ___20___ before your heart stops!

B．For a moment

D．Once in a while

单项选择题

患者朱某，女，53岁。素体气血不足，不慎感受风邪，症见口眼斜，言语不利，手足运动不灵活，舌苔白，脉浮数。治宜选用（）

A.地黄饮子

B.牵正散

C.大秦艽汤

D.小活络丹

E.补阳还五汤