问题 计算题

刘彬同学的姑父从三峡搬迁到我们家乡后,准备兴建一座碳酸钙精粉厂。为检测当地石灰石中碳酸钙的纯度,他在实验室用6g石灰石样品(杂质不参加反应)与19g稀盐酸恰好完全反应,测得残留物为22.8g。 求:

(1)依椐质量守恒定律,生成二氧化碳           g;

(2)样品中碳酸钙的质量分数;

(3)所用稀盐酸溶液中溶质的质量分数。

答案

解:

(1):2.2g

(2)、(3):设石灰石中碳酸钙的质量为x,氯化氢的质量为y

    CaCO3 + 2HCl === CaCl2 + H2O + CO2

     100         73                                   44

      x            y                                    2.2g 

  

石灰石中碳酸钙的质量分数: 

    

稀盐酸中溶质的质量分数:

单项选择题 A1型题
阅读理解

阅读理解

    The giant panda is known as the national treasure of China. The panda was a kind of common animal in China long ago. However, for some reasons, too many of them have been killed. So the number of them is falling quickly? The Chinese government has adopted an important measure to save pandas. People want   to f1nd a home for them, and recently, they have set up a nature park for them in Sichuan Province, which  is called“the Pandas' Home”. There pandas can. enjoy their lives happily. There is a bamboo forest near   "the Pandas' Home", so the pan-das can find bamboos easily which they like to eat very much.    

    Because pandas are well protected now , the number of them is increasing every year. We hope that    one day we will have enough pandas to set them free and let them live in the wild again.    

    Pandas are good friends of man. Man should try to protect them and let them live in the way they   like!

1. In the passage we can know that_________.  

A. the panda is a kind of common animal  

B. the panda is a rare animal    

C. there are many pandas in China    

D. the pandas like eating bamboo only

2. In the passage , the writer mentioned    

A. the number of pandas is getting more and more   

B. the number of pandas is getting less and less  

C. the number of pandas is getting close to zero    

D. he wanted to raise one as pet

3. The Chinese government ____ to save pandas.     

A. had nothing to do      

B. had something to do  

C. wanted to get a hand    

D. had found out a perfect way

4. In the passage ,a nature park means _____. 

A. a small house        

B. a warm home  

C. a nature reserve    

D. a big zoo in which people can watch the show of pandas

5. Which is NOT true of the following?  

A. We protect them in order to let them live in the way they like.    

B. We protect them in order to let them perform for Us.  

C. The writer loves pandas very much.  

D. Chinese government has set up a nature reserve for pandas in Sichuan.