问题 选择题

室温下,下列各组离子能大量共存的是(  )

A.稀硫酸中:K+、Mg2+、AlO2-、S2O32-

B.NaHS溶液中:SO42-、K+、Cl-、Cu2+

C.

KW
c(H+)
=10-13mol•L-1溶液中:Fe3+、NH4+、Mg2+、SO42-

D.通入大量CO2的溶液中:Na+、ClO-、CH3COO-、HCO3-

答案

A、AlO2-、S2O32离子能够与稀硫酸中的氢离子反应,镁离子能够与偏铝酸离子发生双水解反应,在溶液中不能大量共存,故A错误;

B、Cu2+与NaHS发生反应生成氢氧化铜和硫化氢气体,在溶液中不能大量共存,故B错误;

C、溶液为酸性溶液,Fe3+、NH4+、Mg2+、SO42-离子之间不满足离子反应发生条件,也与溶液中的氢离子反应,在溶液中能够大量共存,故C正确;

D、ClO-离子能够与二氧化碳反应生成次氯酸,通入二氧化碳后次氯酸根离子不能共存,故D错误;

故选C.

阅读理解

Today almost everyone knows computers and the Internet. If I ask you “What is the most important thing in your life?” maybe you will say “Computers and the Internet”.

The first computer was made in 1946. It was very big but it worked slowly.. Today, computers are getting smaller and smaller, but they work faster and faster. What can computers do? A writer has said, “People can't live without computers today.”

The Internet came a little later than computers. It is about 25 years later than computers. But now it can be found almost everywhere. We can use it to read books, send e-mails, do some shopping, play games or make friends.             

Young men, especially the middle school students like the Internet very much. They often go into the Internet bars as soon as they are free. They make friends on the Internet and maybe they have never seen these friends. They don't know their names, ages and sex. They are so interested in making the “unreal friends” that they can't put their heart into study. Some of them play the games in the Internet bars all day and all night. Many of them can't catch up with others in many subjects because of that.

Now the government has done many things. Some gangster Internet bars(黑网吧)have been banned. But that's not enough. The teachers and parents are still worrying about their students and children.

We can use computers and the Internet to learn more about the world. But at the same time, we should remember that computers and the Internet could not do all the things.

小题1:How was the first computers?

A.It was not big.

B.It couldn't work fast.

C.It was very cheap.

D.It was no useful小题2:When did people begin to use the Internet?

A.In the 19th century.

B.In the 1980s.

C.In the 1970s.

D.In the 1960s小题3:Which of the following is true?

A.Computers can help people do everything.

B.Middle school students aren't allowed to use the Internet.

C.Some students have used the Internet bars to make the “unreal friends”.

D.computer isn’t good to students.小题4:Which is the best title of the passage?

A.Computers and the Internet.

B.The Greatest Invention of This Century.

C.Gangster Internet Bars.

D.How to use the Internet小题5:What's the meaning of the word “that” in the fourth paragraph ?

A.Students often go into the Internet bars as soon as they are free.

B.And they play the games in the Internet bars all day and all night.

C.Students are so interested in making the “unreal friends” that they can't put their heart into study.

D.All of above

单项选择题