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实验室有一瓶新配制的稀盐酸（HCl气体溶于水得到的混合物为稀盐酸），其标签的部分内容如图所示．

（1）计算该稀盐酸中氯元素的质量分数．

（2）某实验小组用这种稀盐酸测定某石灰石样品中碳酸钙的质量分数，实验过程是：称取10g石灰石样品研成粉末，向其中加入7.3%的稀盐酸，产生二氧化碳的质量与加入盐酸的质量关系如图所示．（假设样品中的杂质都不和盐酸反应）计算石灰石样品中碳酸钙的质量分数．

答案

（1）该稀盐酸中氯元素的质量分数为

500g×7.3%×
35.5
36.5
500g
×100%=7.1%

（2）由图象可知该样品完全反应后生成的二氧化碳质量是3.52g；

设石灰石样品中碳酸钙的质量为x  

CaCO3+2HCl═CaCl2+H2O+CO2↑

100                   44

x                   3.52g

100
x
=
44
3.52g

x=8g

石灰石样品中碳酸钙的质量分数为：

8g
10g
×100%=80%

答：（1）该稀盐酸中氯元素的质量分数为7.1%．（2）石灰石样品中碳酸钙的质量分数是80%；

单项选择题

有以下程序：
int a=2；
int f(int n)
static int a=3；
int t=0；
if(n%2)static int a=4;t+=a++;
elsestatic int a=5;t+=a++；
return t+a++;

main()
int s=a,i；
for(i=0;i＜3;i++)s+=f(i)；
printf("%d\n",s)；

程序运行后的输出结果是______。

A) 26
B) 28
C) 29
D) 24
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单项选择题

Who won the World Cup 1994 football game What happened at the United Nations How did the critics like the new play (1) an event takes place, newspapers are on the streets (2) the details. Wherever anything happens in the world, reporters are on the spot to (3) the news.

Newspapers have one basic (4) , to get the news as quickly as possible from its source, from those who make it to those who want to (5) it.

Radio, telegraph, television, and (6) inventions brought competition for newspaper. So did the development of magazines and other means of communication. (7) , this competition merely spurred the newspapers on. They quickly made use of the newer and faster means of communication to improve the (8) and thus the efficiency of their own operations. Today more newspapers are (9) and read than ever before. Competition also led newspapers to branch out into many other fields. Besides keeping readers (10) of the latest news, today’s newspapers (11) and influence readers about politics and other important and serious matters. Newspapers influence readers’ economic choices (12) advertising. Most newspapers depend on advertising for very (13) .

Newspapers are sold at a price that (14) even a small fraction of the cost of production. The main (15) of income for most newspapers is commercial advertising. The (16) in selling advertising depends on a newspaper’s value to advertisers. This (17) in terms of circulation. How many people read the newspaper

Circulation depends (18) on the work of the circulation department and on the services or entertainment (19) in a newspaper’s pages. But for the most part, circulation depends on a newspaper’s value to readers as a source of information (20) the community, city, county, state, nation, and world—and even outer space.

1（）

A.Just when

B.While

C.Soon after

D.Before
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