问题 选择题

将铜丝烧热,迅速插入氢气中,发生反应:CuO+H2

  △  
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Cu+H2O.若用下列物质代替氢气进行上述实验:①氨气、②稀硝酸、③稀盐酸、④乙醇、⑤一氧化碳,铜丝所发生的变化情况与上述实验完全相同的是(  )

A.①②③⑤

B.①④⑤

C.①③⑤

D.①③④⑤

答案

CuO+H2

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Cu+H2O中,H元素的化合价升高,氢气为还原剂,

①氨气中N元素的化合价为最低价,则氨气具有还原性,能代替氢气来实验;

②稀硝酸中N元素的化合价为最高价,具有氧化性,则不能代替氢气;

③稀盐酸不具有强还原性,则不能代替氢气来实验;

④乙醇具有还原性,则能代替氢气来实验;

⑤一氧化碳是常用的还原剂,具有还原性,则能代替氢气来实验;

故选B.

单项选择题
阅读理解

阅读理解。

     According to the American Automobile Association, since 1964 all cars sold in the United States have

been equipped with seat belts. (These are also called safety belts.) Mary studies of automobile accidents

have shown that safety belts can save lives. One study showed that forty percent of those killed in auto

accidents could have been saved if they had been wearing seat belts.

     Unfortunately belts are worn only by a small percentage of drivers and passengers-about fifteen percent

in cities, and only nine percent in small towns. And safety belts cannot protect people who do not wear them.

     In order to find out what kinds of people do wear seat belts a study was made in several cities of the

United States. The following facts were learned about those who use their safety belts:

     1. They do not smoke while driving.

     2. They have had more education than non-users.

     3. They know someone who was injured(but not killed)in an automobile accident.

     Advertisements based on these facts have been printed in newspapers and magazines in order to teach

people the importance of using seat belts. But these advertisements have not helped much. Some people

believe there should be a law requiring drivers and passengers to use safety belts. In Australia, where there

is such a law, deaths in auto accidents have decreased twenty-four percent.

1. This selection is mainly about _____.

A. automobiles in the United States

B. accidents involving cars

C. safety belts for drivers and passengers

D. parking problems

2. The selection says that in Australia _____.

A. about 50% of the drivers wear seat belts

B. the importance of seat belts is advertised in newspapers

C. few people use seat belts and magazines

D. a law requires drivers and passengers to use seat belts

3. People who live in small towns _____.

A. have fewer accidents than those who live in cities

B. are less likely to wear seat belts than those who live in cities

C. ten to favor the passing of a law to require the use of seat belts

D. often wear seat belts

4. In Australia, where there is such a law, deaths in auto accidents have decreased _____.

A. fifty percent

B. ten percent

C. fifteen percent

D. twenty-four percent