问题 选择题

下列说法不正确的是(   )

A.充电电池充电时,发生电解池反应;放电时,发生原电池反应

B.电镀时,应将镀层金属与电源正极相连

C.电解饱和NaCl溶液时,阳极上放出黄绿色气体的同时还产生大量的氢氧化钠

D.利用电化学原理保护金属主要有两种方法,分别是牺牲阳极的阴极保护法和外加电流的阴极保护法

答案

答案:C

题目分析:电解饱和NaCl溶液时,阳极产生氯气,阴极产生氢气和NaOH,所以C错误,其余选项均正确。

点评:电解中最关键的是准确判断出电极上离子的放电顺序。在判断电解产物时,首先判断阳极电极材料。如果是活性电极,则电极本身失去电子。如果是惰性电极,则溶液中的阴离子失去电子。而阴极是溶液中的阳离子得到电子,所以需要熟练记住常见离子的放电顺序。

阅读理解

                              A

George had stolen some money, but the police had caught him and he had been put in prison. Now his trial was about to begin, and he felt sure that he would be found guilty and sent to prison for a long time.

Then he discovered that an old friend of his was one of the members of the jury at his trial. Of course, he did not tell anybody, but he managed to see his friend secretly one day. He said to him, "Jim, I know that the jury will find me guilty of having stolen the money. I cannot hope to be found not guilty of taking it —— that would be too much to expect. But I should be grateful to you for the rest of my life if you could persuade the other members of the jury to add a strong recommendation for mercy to their statement that they consider me guilty."

“Well, George,”answered Jim. “I shall certainly try to do what I can for you as an old friend, but of course I cannot promise anything. The other eleven people on the jury look terribly strong-minded to me.”

George said that he would quite understand if Jim was not able to do anything for him, and thanked him warmly for agreeing to help.

The trial went on, and at last the time came for the jury to decide whether George was guilty or not. It took them five hours, but in the end they found George guilty, with a strong recommendation for mercy.

Of course, George was very pleased, but he did not have a chance to see Jim for some time after the trial. At last, however, Jim visited him in prison, and George thanked him warmly and asked him how he had managed to persuade the other members of the jury to recommend mercy.

"Well, George," Jim answered, "as I thought, those eleven men were very difficult to persuade, but I managed it in the end by tiring them out. Do you know, those fools had all wanted to find you not guilty!"

小题1:56. We are told that George expected Jim to help _____.

A.prove him innocent

B.him turn over a new leaf

C.lighten his punishment

D.him escape from prison小题2:57. Which of the following is true about Jim?

A.He covered up George's guilt.

B.He persuaded the jury to set George free.

C.He told the jury that George was indeed guilty.

D.He recommended severe punishment to give George a lesson.小题3:58. The passage suggests that _____.

A.it was due to Jim that George was found guilty

B.Jim did not do exactly what George asked him to do

C.Jim asked his colleagues to recommend mercy

D.Jim persuaded the jury to lighten George's punishment小题4:59. The title for this passage is ______.

A.Illegal or Not?

B.Guilty or Not?

C.Merciful or Not?

D.Answerable or Not?

单项选择题