问题 填空题

有一包固体A,可能含有Cu(OH)2、CuO、Cu、NaOH、Na2CO3、CaCl2中的几种,取少量的A做如下实验,现象如图所示.根据实验过程中的现象判断:

(1)气体D是______(填化学式,下同);溶液F的溶质是______.

(2)混合物A的可能组成是 (填一种)______.

(3)写出过程③中可能发生的化学反应中的一个化学方程式______.

答案

(1)分析图中物质间的反应图示可知:在Cu(OH)2、CuO、Cu、NaOH、Na2CO3、CaCl2中能溶于水且与稀盐酸起反应放出气体的,只有Na2CO3,由此也可推断出气体D是CO2,固体A中一定有Na2CO3;因为有Na2CO3,Na2CO3和CaCl2反应生成碳酸钙沉淀,不可能同时存在CaCl2,固体A中一定没有CaCl2

    (2)Cu(OH)2、CuO都不溶于水,不论Cu(OH)2、CuO是同时存在还是只存其中一种,与稀硫酸起反应得到的蓝色溶液的溶质都是CuSO4,硫酸是过量的,还有剩余,可推出F的溶质是CuSO4、H2SO4;Cu(OH)2、CuO存在情况是:都存在或只存在其中一种;

   (3)不溶于水又不与稀硫酸发生反应的物质是Cu,由此也可推断出G是Cu.

    综上所述,固体A中一定存在的物质有Na2CO3、Cu,一定没有CaCl2,Cu(OH)2、CuO存在情况是:都存在或只存在其中一种;可能存在的物质是NaOH.

    故答为:(1)CO2,CuSO4、H2SO4

    (2)Na2CO3、CuO、Cu;

    (3)CuO+H2SO4═CuSO4+H2O.

阅读理解

The good things about computer games

They’re fun!

They can improve hand-eye coordination. That means you can think and do things more quickly.

You feel good when you can move up levels and see how well you’re doing.

Most games make you think about what you’re going to do, and they can help you improve the ability (能力) of solving problems.

You can play games on the Internet with people from all over the world.

Anyone can play computer games, even if they aren’t very good at sports, have a disability, or find it hard to talk to others.

The bad things about computer games

Kids may start hitting others in their lives just as they do in games because they may think it’s OK to hit others, or to talk to people, including their parents and teachers, impolitely.

If kids play games for a long time, they may not go out and exercise. They may start eating snacks while they play games and they will become too fat. Doctors are worried about kids that play too many computer games.

Playing games is a big problem for some people. They will play or think about games when they have time. This means they may stop talking with others and become really boring people.

小题1:How many good things about computer games does the writer mention?

A.Three.

B.Six.

C.Seven.

D.Nine.小题2:What does the underlined word “coordination” mean in Chinese?

A.协调

B.障碍

C.舒适

D.问题小题3:If you play computer games all the time, you may become a(n) ______ person.

A.healthy, impolite and boring

B.healthy, polite and boring

C.unhealthy, polite and boring

D.unhealthy, impolite and boring小题4:Which of the following is NOT true according to this passage?

A.Most games are good for your ability of solving problems.

B.You can’t play games with strangers on the Internet.

C.Playing too many computer games may make you fat.

D.Playing games can also cause many problems.小题5:The passage is mainly about       .

A.the two sides of computer games

B.how to improve your computer games skills

C.playing computer games with others

D.some interesting things about computer games

单项选择题