问题 选择题

以NA代表阿伏伽德罗常数,则关于热化学方程式C2H2(g)+O2(g)===2CO2(g)+H2O(l) ΔH=-1300 kJ/mol的说法中,正确的是(  )

A.当12NA个电子转移时,该反应放出1300 kJ的能量

B.当1NA个水分子生成且为液体时,吸收1300 kJ的能量

C.当有2NA个碳氧共用电子对生成时,放出1300 kJ的能量

D.当有8NA个碳氧共用电子对生成时,放出1300 kJ的能量

答案

答案:D

题目分析:根据热化学方程式可知,该反应是放热反应,B不正确;每消耗1mol乙炔,反应中就转移2.5mol×4=10mol电子,同时生成2molCO2,即有8mol碳氧共用电子对,因此正确的答案选D。

点评:该题是高考中的常见题型,侧重对学生基础知识的训练和检验。该题的关键是明确反应热和热化学方程式的含义,然后结合题意和具体的化学方程式灵活运用即可,有利于调动学生的学习兴趣和学习积极性,提高学生的灵活应变能力。

多项选择题
阅读理解

For many years, I was convinced that my suffering was due to my size. I believed that when the weight disappeared, it would take old wounds, hurts, and rejections with it.

Many weight – conscious people also mistakenly believe that changing our bodies will fix everything. Perhaps our worst mistake is believing that being thin equals being loved, being special, and being cherished. We fantasize(梦想)about what it will be like when we reach the long – awaited goal. We work very hard to realize this dream. Then, at last, we find ourselves there.

But we often gain back what we have lost. Even so, we continue to believe that next time it will be different. Next time, we will keep it off. Next time, being thin will finally fulfill its promise of everlasting happiness, self–worth, and, of course, love.

It took me a long while to realize that there was something more for me to learn about beauty. Beauty standards vary with culture. In Samoa a woman is not considered attractive unless she weighs more than 200 pounds. More importantly, if it’s happiness that we want, why not put our energy there rather than on the size of our body? Why not look inside? Many of us work hard to change our body, but in vain. We have to find a way to live comfortable inside our body and make friends with and cherish ourselves. When we change our attitudes toward ourselves, the whole world changes.

小题1:The passage tries to tell us the importance of          .

A.body size

B.attitudes

C.culture difference

D.different beauty standards小题2: What does the word “everything” in paragraph 2 mean?

A.All the problems.

B.All the properties

C.The whole world

D.The absolute truth小题3: What can be inferred about the author?

A.The author is a Samoan

B.The author succeeded in losing weight

C.The author has been troubled by her/his weight.

D.The author probably got wounded in wars or accidents.小题4:. According to the author, what is the common view of those who have lost some weight first and gained it back later?

A.They feel angry about the regained weight

B.They are indifferent to the regained weight

C.They feel optimistic about future plans on weight control.

D.They think they should give up their future plans on weight control.