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（10分）铅蓄电池是化学电源，其电极材料分别是Pb和PbO2，电解质溶液为稀硫酸。工作时，该电池的总反应为PbO2+Pb+2H2SO4=2PbSO4+2H2O，根据上述情况判断：

（1）蓄电池的负极是______，其电极反应式为______________________________。

（2）蓄电池的正极电极反应式为_________________________________。

（3）蓄电池工作时，其中电解质溶液的pH______（增大、减小、不变）。

答案

阅读理解

Most of you know this mathematical game, of course. You and your friend draw crosses and circles on a sheet of paper. You do it one after another. The first pupil who gets three marks in a row wins. But do you know that you can play this game another way and it will become more interesting? You must try to make your friend win. If you get your three marks in a row, you don’t win — you lose!

It is more difficult to play this game the other way. The second pupil can always win (if he plays the right way), but he may not win if the first pupil begins with his mark in the center. Then if the first pupil always takes a place on the other side of his friend’s mark, nobody will win.

If your friend does not know the secret which we have explained, you must play each time so as to leave him the greatest number of ways to win. You may try a few games and you will see how interesting it is to play the game this way.

小题1: The passage tells us that it is _____ to play this game.

A．interesting

B．difficult

C．impossible

D．unusual小题2:What s the new rule of the game if we play it another way?

A．The one who gets his three marks in a row wins.

B．The one who makes his friend win wins.

C．The one who plays the right way wins.

D．The one who makes his friend lose wins.小题3:According to the new rule of the game, the second player can always win if the first player __.

A．begins with his mark in the center

B．takes a place on the other side of his friend’s mark

C．tries to get his three marks in a row first

D．doesn’t begin with his mark in the center小题4: What result does the following picture show?

○ =" the" 1st player   × =" the" 2nd player

A．Both of the players win.

B．The first player wins.

C．Neither of the players wins.

D．The second player wins.小题5: What is the best title for this passage?

A．What an Interesting Game

B．A Game of Circles and Crosses

C．The Secret We Want to Explain

D．Marks on a Sheet of Paper
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问答题

元素周期律和元素周期表对深化物质性质的认识具有重要的作用，有利于将零乱的元素化合物知识整合起来形成知识网络．某同学整理了关于氯元素的相关知识，请你补充完整．

（1）氯元素的原子结构示意图为______，在周期表中的位置为______．

（2）氯、硫、磷三种元素对应的气态氢化物中，稳定性由强到弱的顺序为______，氯、溴两种元素的单质中，氧化性强的是______，设计简单的实验方案证明______．

（3）含有氯元素的常见物质转化关系如图：，A、B中氯元素化合价的代数和为0，且均是共价化合物，A为强电解质，B具有漂白性，写出A→Cl2的化学反应方程式______；C与B的组成元素相同，C中氯元素的化合价为最高价，C与H2SO4相比，酸性强的是______（填化学式）．
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