问题 填空题

某同学为了探究物质的性质,以氧气为例,做了如下实验:如图所示.先收集了两瓶氧气(注意:瓶口向上)后正放在桌上,盖好玻璃片,然后用带火星的木条插入A集气瓶中,在B瓶中放入一只昆虫.

请回答下列问题

(1)观察到的实验现象:A瓶______;B瓶______;

(2)探究得出氧气的部分性质:物理性质______;化学性质______;

(3)除了以上的探究内容外,该同学还可以从哪些方面探究氧气的性质?请你帮助该同学设计一实验探究氧气的其他性质.______.

答案

(1)因为氧气具有助燃性,故A瓶的现象为带火星的木条复燃;因为氧气还具有供给呼吸的作用,昆虫在B瓶中短时间生活正常.

(2)由瓶口向上后正放在桌上可知氧气的物理性质为密度比空气密度大,由AB两瓶的现象可知氧气的化学性质为支持燃烧,供给呼吸;

(3)可探究氧气的水溶性,通过排水取气法可探究氧气的水溶性为不易溶于水.

故答案为:(1)带火星的木条复燃;昆虫在B瓶中短时间生活正常;(2)密度比空气密度大;支持燃烧供给呼吸;(3)通过排水取气法可探究氧气的水溶性为不易溶于水

阅读理解
阅读理解。
        A new school term begins. Is anything new at your school? Sichuan students are getting an extra (额外的) hour to sleep in the morning.
        This year, Sichuan schools decided that students should start classes later. This should help them feel less
tired, For Junior high schools, the first classes will begin no earlier than 8:30 am.
        The changes have made students happy.
        Liu Xian, 15, said his class was excited by the news on the first day of school.
       "It's so good we can get up later!" said Liu.
        Liu studies in Chengdu No.4 Middle School. He used to get up at 6:40 am. Now he can get up at 7:40 am
because class doesn't start until 8:40 am.
        Wu Hongli, 15, said the new timetable is good for her health. "I used to drink coffee every night or I would
feel too sleepy to finish my homework, "said Wu. "Now I can finish it without coffee." She used to get up at 6:30
am. Now she can get up at 7:30 am.
        Wu Hongli's mother was happy, too. She thought more sleep would help her daughter grow taller.
        But some parents worried that more sleep would mean less learning. There used to be five classes in the
morning. Now there are only four.
        Many teachers, though, say the changes will help students learn better. 
       "Students used to doze (瞌睡) for the first two classes in the morning," said Wu Zongping, an English
teacher at Chengdu No.12 Middle School. "But now they look fine and they learn much better than before."
1. What made the Sichuan middle school students happy?
[ ]
A. The new school term began.
B. Their schools took on a new look.
C. They felt a little bit tired.
D. They could get up later.
2. In the new term, the first class in the morning in middle schools started at about             .
[ ]
A.7:00
B.7:30
C.8:00
D.8:40
3. Why was Liu Xian excited at the news on the first day of school?
[ ]
A. There were many changes in his school.
B. He could sleep one more hour in the morning.
C. He could study in Chengdu No.4 Middle School.
D. He would have only five classes in the morning.
4. What did the teachers think of the changes of the school timetable?
[ ]
A. They didn't like the changes.
B. They could use the timetable more easily.
C. They spoke highly of the changes.
D. They looked fine when they taught.
选择题