问题 选择题

最早使用的化学电源是锌锰电池,即大家所熟悉的干电池(dry cell),其结构如图所示:尽管这种电池的历史悠久,但对它的电化学过程尚未完全了解.一般认为,放电时,电池中的反应如图:

E极:2MnO2+2H2O+2e-═2MnO(OH)+2OH-

F极:Zn+2NH4Cl-2e-═Zn(NH32Cl2+2H+

总反应式:2MnO2+Zn+2NH4Cl═2MnO(OH)+Zn(NH32Cl2

下列说法正确的是(  )

A.E极是电池的正极,发生的是氧化反应

B.F极是电池的负极,发生的是氧化反应

C.从结构上分析,锌锰电池应属于可充电电池

D.锌锰电池内部发生的氧化还原反应是可逆的

答案

A、原电池的E极发生的是得电子的还原反应,是正极反应,故A错误;

B、原电池的F极发生失去电子的氧化反应,F电极应该是负极,故B正确;

C、从结构上分析,锌锰电池应属于一次电池,故C错误;

D、锌锰电池应属于一次电池,一次电池内部发生的氧化还原反应是不可逆的,故D错误.

故选B.

选择题
阅读理解

阅读理解。

     Robert was born in a small town in England. His father has a farm and can supply him enough money to

finish university where he is studying law. The young man studies hard and hopes to be a famous lawyer.

     Last Monday their term was over. Robert said to his father on the telephone that he was going to travel in

a small country during his summer holiday. His father agreed to his plan and posted some money to him. So

he started four days ago. Their plane landed at the only airport of the country safely. He took a taxi and got to

a hotel in the center of the capital. He felt hungry and tired. So he had a dinner and then a good sleep. This

morning he was all right and was going to visit some places of interest. He met an English visitor while he was

having breakfast and the man told him to be careful of thieves.

     Robert thanked the man and left. But he thought he was smart and strong and he decided to have a try. He

brought a piece of paper and wrote on it, "A pig has stolen my wallet!" Then he put the note into his empty

wallet. After that he put the wallet into a pocket and set off. He did all carefully and hoped to find out who

would steal it.

     "Everything went well, "Robert thought to himself after he had returned to the hotel. He brought out his

wallet and put his money into it again. He had a look at the note. To his surprise, it was rewritten. It said,

"Your uncle has touched your wallet!"

1. Robert can study in the university because            . [ ]

A. he wants to be a lawyer

B. his father is a rich farmer

C. he's smart and strong

D. he keeps his wallet well

2. Robert went to the small country to            . [ ]

A. make fun of the thieves

B. catch some thieves

C. visit the places of interest

D. have a nice meal and a good sleep

3. The English visitor thought            . [ ]

A. there were a lot of thieves in the city

B. Robert could deal with the thieves

C. it was dangerous to travel in the city

D. Robert had to take good care of himself