问题 问答题

以下是实验室用高锰酸钾制取氧气并用排水法收集的实验.请按要求回答问题:

(1)描述氧气已经集满的现象:______.

(2)停止实验时,要先移开导管,再熄灭酒精灯.其原因是:______.

(3)请将下列实验步骤进行正确排序:

A、给试管加热

B、用排水法收集氧气

C、熄灭酒精灯

D、装高锰酸钾于试管

E、将导管移出水面

F、检查装置的气密性

G、把试管固定在铁架台上,且集气瓶注满水倒置在水槽中.

正确的实验顺序是(填序号)______.

(4)用收集的氧气做木炭在氧气中燃烧的实验:

请描述燃烧现象______.

方程式为______.

答案

(1)排水法收集气体集满的标志是集气瓶口有气泡向外冒出;

(2)用排水法收集氧气,停止实验时,要先移开导管,再熄灭酒精灯,防止水槽中的水倒流入试管,使试管炸裂.

(3)实验室用高锰酸钾制氧气的步骤可简记为:查装定点收离熄.所以顺序为FDGABEC.

(4)木炭在氧气中燃烧的现象为发出白光,放出热量,生成使澄清石灰水变浑浊的气体.化学方程式为

C+O2

 点燃 
.
 
CO2

故答案为:(1)集气瓶口有气泡向外冒出;(2)防止水槽中的水倒流入试管,使试管炸裂.(3)FDGABEC

(4)发出白光,放出热量,生成使澄清石灰水变浑浊的气体.C+O2

 点燃 
.
 
CO2

阅读理解

阅读理解。

     A history teacher was talking to his class about the ancient Romans (古罗马人). "They were very strong,

brave people, and they were good soldiers, too," he said."They always wanted to have strong bodies, so they

played a lot of games."

     "Did they like swimming?" one of the girls asked. "That makes people strong." She was very good at

swimming. "Oh, yes, some of them swam a lot," the teacher answered. Then he told them a story about a

famous Roman. "There was a big, wide river in the middle of Rome," he said, "and one man swam across it

three times every day before breakfast!"

     The girl laughed when she heard this. "Why are you laughing?" the teacher asked her angrily. "Did I say

something interesting?" "Well, sir," the girl answered, "Why didn't he swim across the river four times to get

back his clothes back?"

1. The ancient Romans played many games because ______.

A. they were not old enough

B. they were free

C. they wanted to be strong

D. they were not brave

2. The teacher taught ______.

A. swimming

B. English

C. history

D. P.E.

3. The girl asked the teacher if (是否) the Romans like swimming because ______.

A. she was a good swimmer

B. the teacher was good at swimming

C. she was going to learn swimming

D. she didn't like swimming 

4. The underlined (划线的) word "them" means here ______.

A. the teachers

B. the girls in the class

C. the Romans

D. Strong, brave people

5. Why did the girl laugh?

A. Because the teacher was interesting.

B. Because the man swam without (没有) breaast.

C. Because the man couldn't swim at all.

D. Because she didn't understand the teacher.

单项选择题 A型题