问题 问答题

通过计算回答:12克镁和12克氧气反应,最多可得到氧化镁多少克?

答案

根据镁与氧气反应的化学方程式可知,48份质量的镁与32份质量的氧气恰好完全反应,故12克镁和12克氧气反应镁质量不足,设12g镁与氧气反应生成氧化镁的质量为x

2Mg+O2

 点燃 
.
 
2MgO

48  32        80

12g           x

 

48
80
=
12g
x

解得x=20g

答:12克镁和12克氧气反应,最多可得到氧化镁20g.

阅读理解

This is news on the Hour. Ed Wilson is reporting. The President and First Lady will visit Africa on a goodwill tour in May. They plan to visit eight African countries.

Reports from China say the Chinese want closer ties between China and the U.S. and Western Europe. A group of top China scientists starts its ten-nation tour next month.

Here in Milmi, the mayor is still meeting with the leaders of the teachers’ union to try to find a way to end the strike. City schools are still closed after two weeks.

In news about health, scientists in California report findings of relationship between the drinking of coffee and the increase of heart disease among woman. According to the report in the American Medical Journal, the five-year study shows this: women who drink more than two cups of coffee a day have a greater chance of having heart disease than women who do not.

In sports, the Chargers lost again last night. The BBS beat them one to nothing. The Wingers had better results. They beat the Rifles 7 to 3.It was their first win in their five matches.

That the news of the Hour. And now back to more easy listening with Jan Singer.

小题1:The passage is about______

A.an official visit to Africa

B.the improvement of relationship between China and the U.S.

C.the news broadcast on the air

D.the strike led by the teachers’ union小题2:From the last news we do not know______

A.the results of the matches

B.the number of the team which played last night

C.how many wins the BBS has had altogether

D.the Wingers had one win and four defeats小题3:The news about health tells us that_______

A.no heart disease will be found if people don’t drink coffee

B.no one should drink more than two cups of coffee a day

C.the more coffee people drink, the more chances they will get to have disease

D.women’s heart disease has something to do with the drinking of coffee.小题4:What is the purpose for China scientists to visit ten nations next month?

A.China expect closer ties between China and the U.S. and Western Europe.

B.They want to travel abroad

C.They need a rest

D.They are seeking for an opportunity to work abroad.

单项选择题