问题 实验题

某研究性学习小组设计了一组实验来验证元素周期律。

I.甲同学在a、b、c三只烧杯里分别加入50 mL水,再分别滴加几滴酚酞溶液,依次加入大小相近的块状锂、钠、钾,观察现象。

(1)甲同学设计实验的目的是____,反应最剧烈的烧杯是____(填字母)

Ⅱ.乙同学设计实验验证氮、碳、硅元素的非金属性强弱,实验装置如上图所示。乙同学设计的实验可直接证明三种酸的酸性 强弱,已知A是强酸,常温下可与铜反应,B是难溶性块状固体;打开分液漏斗的活塞后,C中可观察到白色沉淀生成(其中溶液足量)。

(2)写出所选物质或溶液中溶质的化学式: A___________,B____________,C___________。

(3)写出烧瓶中发生反应的离子方程式:_____________________。

(4)写出烧杯中发生反应的离子方程式(不考虑杂质的反应)________________________。  

答案

(1)验证锂、钠、钾的活泼性(或验证同一主族从 上到下元素的金属性逐渐增强);c   

(2)HNO3 ;CaCO3 ;Na2SiO3(或K2SiO3

(3)CaCO3+2H+=Ca2++H2+CO2↑ 

(4)CO2+SiO32- +H2O=H2SiO3↓ +CO32-

阅读理解

阅读理解。

     Spending just a few hours a week online may make people feel more socially isolated(孤立的),

lonely and downhearted(沮丧的), according to a two-year study of nearly 100 families with the

Internet.

     "We were surprised to find that social technology has such bad effects on social communications,"

the lead author, Dr. Robert Kraut of Carnegie Mellon University in Pittsburgh, Pennsylvania, said in a

statement to the news. The findings suggest that "Rather than encourage students to use the Internet

alone for research, teachers might give pupils online group homework to complete with classmates.

Local groups might build websites that allow neighbors to discuss local affairs(地方事务)."

     "Before the technology develops and can be really more beneficial, people should control(控制)

their wishes to use much of the Internet," Dr. Kraut and other experts advise. In order to control their

children and encourage family activities, parents might think of putting the computer in the living room

rather than in a child's room, they suggest.

     Dr. Kraut also suggests that when surfing on the net, especially when chatting with strangers on the

net, children should not use their real names, and that they should not tell the addresses, telephone

numbers to the strangers.

1. According to the research, surfing on the Internet can make people feel more            .

A. excited              

B. communicative

C. lonely                

D. happy

2. This study was made by            .

A. 100 families

B. Dr. Kraut and other experts

C. the newspaper

D. Dr. Kraut only

3. This research work took          .

A. a week          

B. a few hours

C. two years        

D. more than 100 days

4. According to the context(上下文), "beneficial" means "            " in Chinese.

A. 有害的        

B. 发展的

C. 有趣的        

D. 有益的

5. Which of the following do the experts suggest?

A. Teachers should ask the students to finish their homework alone on the Internet.

B. Schools should build websites for students to discuss problems on the Internet.

C. Instead of putting the computer in the sitting room, parents should put it in a child's room.

D. Children should not give their real names, addresses or telephone numbers to the strangers.

材料分析题