问题 选择题

如图所示a、b都是惰性电极,通电一段时间后,a极附近溶液显红色.下列说法中正确的是(  )

A.X是正极,Y是负极

B.X是负极,Y是正极

C.CuSO4溶液的浓度逐渐减小

D.CuSO4溶液的pH减小

答案

a、b都是惰性电极,通电一段时间后,a极附近溶液显红色,说明a电极有氢氧化钠生成,则a电极上氢离子放电,所以a电极是阴极,b是阳极,X是负极,Y是正极,铜是阳极,铂是阴极,左边装置中,阳极上铜失电子发生氧化反应,阴极上铜离子得电子发生还原反应,

A.X是负极,Y是正极,故A错误;

B.X是负极,Y是正极,故B正确;

C.铜电极上铜失电子生成铜离子进入溶液,铂电极上铜离子得电子生成铜,所以硫酸铜溶液中浓度不变,故C错误;

D.铜电极上铜失电子生成铜离子进入溶液,铂电极上铜离子得电子生成铜,所以硫酸铜溶液中浓度不变,溶液的pH不变,故D错误;

故选B.

单项选择题 A1型题
阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    小题1:     

If your complaint is immediate, suppose you got the wrong order at a restaurant, make a polite but firm request to see the manager.When the manager comes, ask his or her name.And then state your problem and what you expect to have done about it.

Be polite!    小题2:     

But also be firm in making your complaint.

   小题3:     This doesn’t mean to put on airs and say “do you know who I am?” What it means is that people are often treated the way they expect to be treated.If you act like someone who expects a fair request to be granted, chances are that it will be granted .

    小题4:     You are speaking to a voice coming from someone you cannot see.So you can’t tell how the person on the line is reacting.It is easy for that person to give you the run-around.

    小题5:     If your complaint doesn’t require an immediate response, it often helps to complain by letter.If you have an appliance that doesn’t work, send a letter to the store that sold it.Be business-like and stick to the point.Don’t spend a paragraph on how your uncle John tried to fix the problem and couldn’t.

A.Shouting or acting rude will get you nowhere.

B.Complaining in person or by letter is generally more effective.

C.The worst way to complain is over the telephone.

D.Telephone complaint is never efficient.E.The way to complain is to act business-like and important.

F.Besides, act important.

G.There are many ways to complain.