问题 听力题

根据下列句子所给汉语意思,写出空缺处各单词的正确形式。

1. The next thing on our ___________(时间表) is to telephone our friends.

2. Almost all the jobs require ___________(受过教育的) workers.

3. My sister was lucky to be a________ to Beijing University.

4.. The house has an underground p_________(通道).

5. The antiques(古董) have been handed down to them from one _________ (代) to another.

6. After the conference, the secretary passed me a ten-page _______ (纪要,摘要).

7. He has kept a teaspoon as a ________ (纪念品) of his journey.

8. The scientist often ___________(向……投稿) to an academic journal.

9. I would be very________(感激的) if you could give me an early reply.

10. Having a        (均衡的) diet is quite good for our health.

答案

问答题 简答题
实验题

(12分)某同学为了探究锌与硫酸反应过程中的速率变化,他在100mL稀硫酸中加入足量的锌粉,标况下用排水集气法收集反应放出的氢气,实验记录如下(累计值):

时间(min)12345
氢气体积(mL)(标准状况)50120232290310
(1)哪一时间段(指0~1、1~2、2~3、3~4、4~5min)反应速率最大______________,原因是______________________________________________。

(2)哪一时间段的反应速率最小________________,原因是___________________。

(3)求2~3分钟时间段以硫酸的浓度变化来表示的该反应速率(设溶液体积不变,要写出计算过程)______________________________________________________。

(4)该同学在用稀硫酸与锌制取氢气的实验中,发现加入少量硫酸铜溶液可加快氢气的生成速率。请回答下列问题:

①上述实验中涉及到的离子反应方程式有                                            

                                      

②硫酸铜溶液可以加快氢气生成速率的原因是                               

③实验室中现有Na2SO4、MgSO4、Ag2SO4、K2SO4等4种溶液,可与实验中CuSO 溶液起相似作用的是                 

④该同学通过实验进一步研究了硫酸铜的量对氢气生成速率的影响。该同学最后得出的结论为:当加入少量CuSO4溶液时,生成氢气的速率会大大提高。但当加入的CuSO4溶液超过一定量时,生成氢气的速率反而会下降。请分析氢气生成速率下降的主要原因