问题 选择题

在一定温度下可逆反应N2+3H22NH3已达到平衡,下列有关说法正确的   (    )

①1个N≡N键断裂的同时,有3个H—H键形成

②反应混合物中各组分的体积分数保持不变

③恒温恒容时,容器内的压强不再改变

④1个N≡N键断裂的同时,有3个N—H 键形成

⑤NH3生成的速率与NH3分解的速率相等

⑥单位时间生成n molN2,同时生成2n molNH3

⑦气体的平均相对分子质量不再改变

⑧NHNH3的分子数一定为1∶3∶2

⑨恒温恒容时,气体的总物质的量不再改变

⑩恒温恒压时,容器内的密度不再改变

A.①②③④⑤⑥⑦⑨

B.①②③⑤⑥⑩

C.③④⑤⑥⑦⑧

D.①②③⑤⑥⑦⑨⑩

答案

答案:D

题目分析:① 1个N≡N键断裂的同时,有3个H—H键断裂,若形成3个H—H键。单位时间内H—H键断裂的个数与形成的个数相等。证明达到平衡。②反应达到平衡时各物质的物质的量不变,反应混合物中各组分的物质的量也不变,所以体积分数保持不变。正确。③恒温恒容时,反应达到平衡时个种气体的物质的量不变,总物质的量也不变,所以容器内的压强不再改变。正确。④ 在任何时刻每有1个N≡N键断裂的同时,就有3个N—H 键形成,这是反应向正反应方向进行,不能说明反应达到平衡。错误。⑤ NH3生成的速率与NH3分解的速率相等,则氨气的浓度不变,反应达到平衡。正确。⑥单位时间生成n molN2,必然消耗2nmol NH3。同时生成2n molNH3。则NH3的浓度不变,达到平衡。正确。⑦反应符合质量守恒定律。如果气体气体的平均相对分子质量不再改变,说明气体的物质的量不变,即反应达到平衡。正确。⑧NHNH3的分子数一定为1∶3∶2 只是反应过程中的一个非常特殊的情况,可能达到平衡,一可能没达到平衡。错误。⑨该反应是个反应前后气体体积不等的反应,若恒温恒容时,气体的总物质的量不再改变,即各物质消耗的浓度与生成的浓度相等,反应达到平衡。正确。⑩恒温恒压时,容器内的密度不再改变 也就是气体的物质的量不变。该反应是反应前后气体体积不等的反应,若气体的物质的量不变,则反应达到平衡。正确。正确的说法是①②③⑤⑥⑦⑨⑩。选项为:D。

问答题 简答题
完形填空

第一节 完形填空 (共12小题;每小题1分,满分12分)

(1)阅读下面短文,掌握其大意,然后从第31至第40小题所给的A、B、C、D四个选项中,选出最佳选项,并在答题卡上将该项涂黑。

I know my brother better than anyone else in the world. Since the moment of his birth, I’ve been part of his life. I had spent seven  29    years in the world with the attention of those around me. But when Rohan was born, life   30    . Suddenly I had to share my toys and there were no more bedtime stories or my own choice of food.

Finally, I felt my    31     at my brother. The poor baby had no idea what    32     me so unhappy. Maybe he found me strange, the only person in this house    33     did not like him. Whatever the reason was, he loved following me around. However, I seldom talked to him and   34     asked him to leave me alone.

Then all that changed. I hardly remember everything of that day six years ago,   35   I do remember that I was feeling very angry. Somehow my feet led me to my brother’s bed. My hand, completely    36    from my mind, reached through the bars (护栏). At once, he reached out his small hand and softly touched   37     . And that was all I needed. Through all the unhappiness of the day, that one moment changed everything. How could I hate someone who made me     38    so important? For the   39     time, I saw my brother, not through the eyes of a child who was no longer favored (宠爱), but through the eyes of a   40   .

29. A. happy              B. hard          C. lonely              D. busy

30. A. began               B. continued C. changed            D. saved

31. A. fun                  B. anger               C. fear                  D. worry

32  A. makes        B. has made     C. is making          D. had made

33. A. which               B. where        C. who                 D. what

34. A. always             B. already       C. hardly              D. almost

35. A. but                  B. so             C. or                    D. for

36   A. far                   B. sick           C. different           D. free

37   A. one                  B. both          C. mine                D. them

38. A. feel                    B. feeling              C. feels                 D. felt    

39  A. first                 B. second       C. last                  D. next

40. A. student             B. parent       C. teacher             D. sister