问题 填空题

根据下表所列的物质,回答有关问题:

序号
物质过氧化氢纯碱食醋熟石灰
化学式________________________
(1)溶于水,所得溶液呈碱性的盐是______(填序号).

(2)可用于除去热水瓶中水垢的是______(填序号).

(3)用表中的物质作反应物,写出符合下列要求的化学方程式:①实验室制取氧气:______;②制取烧碱:______.

答案

过氧化氢的化学式是H2O2;纯碱是碳酸钠的俗称,其化学式是Na2CO3;食醋的化学式是CH3COOH;熟石灰是氢氧化钙的俗称,其化学式是Ca(OH)2

(1)由盐的定义可知,盐是由金属离子和酸根离子组成的化合物,纯碱属于盐,溶于水,其水溶液显碱性;

(2)碳酸钙可以与酸反应,生成对应的盐和水以及二氧化碳,故可使用酸性物质除去碳酸钙,分析选项所给的物质,食醋显酸性;

(3)①实验室中常用过氧化氢溶液和二氧化锰制取氧气,反应的方程式是:2H2O2

 MnO2 
.
 
2H2O+O2↑;

②工业上常用碳酸钠和氢氧化钙反应制取烧碱,反应的方程式是:Na2CO3+Ca(OH)2=CaCO3↓+2NaOH.

故答案为:H2O2;Na2CO3;CH3COOH;Ca(OH)2;(1)②;(2)③;(3)①2H2O2

 MnO2 
.
 
2H2O+O2↑;②Na2CO3+Ca(OH)2=CaCO3↓+2NaOH.

阅读理解

People at home keep asking me, "Is it hard Why have you learned it so well?" Well, there's one thing that makes Chinese easy to learn: there are so many people to talk to.to learn Chinese? You've probably heard that it's the most spoken language. Today it's also one of the most written languages online. And with so many Chinese people interested in learning English, it couldn't be easier to find a friend for language learning. You just have to know where to look for them.

The really good place to look for them is QQ. QQ has the same status(地位) in China as AIM (AOL Instant Messenger) does in the US. It is reported that at any moment, up to 9,000,000 people are using QQ. They're at work, or in a web café, or at home, and the information of the users can be found. If you sign on with your address set to "abroad", you'll soon find that many thousands of them are interested in speaking to you! This is a great way for you to learn Chinese, and for them to learn English. I think that it's a very interesting way of cultural contact(文化交流), too, for ordinary people from around the world to be able to have one-on-one contact.

小题1:In the first paragraph, the writer tells us ___________.

A. why his family members want to learn Chinese

B. Chinese isn’t so hard to learn as his friends think 

C. the easiest thing to do is learning Chinese

小题2:From the second paragraph we know that QQ and AIM are __________.

A. addresses for the Internet users    

B. documents(文件) you need to get online

C. tools(工具)for people to talk online      

小题3:Offices, web cafés and homes ____________.

A. have the most people online

B. provide both QQ and AIM in China

C. are the best places for English learners  

小题4:The writer wrote this passage mainly to __________.

A. tell a way of learning Chinese      

B. show what the Chinese people are doing

C. tell the importance of learning Chinese 

小题5:The writer of this passage is maybe ___________.

A. a Chinese who works abroad      

B. an expert(专家)who works at home

C. an American who works in China  

单项选择题