问题 问答题

根据提供的药品及操作要点,选择合适的除杂方法填空(填序号):

药品:a.足量的氧气;b.足量的稀硫酸;c.过量的铁粉;d.足量的氢氧化钠溶液;e.足量的灼热的氧化铜

操作:A.过滤,B.蒸发.

物质(括号内为杂质)去杂质试剂去杂质操作
铜粉(铁粉) 
二氧化碳(氢气) ----------------------------
硫酸亚铁溶液(硫酸铜溶液)  
硫酸钠晶体(碳酸钠)  

答案

铜粉中混有的铁粉可与所提供试剂中的稀硫酸反应而被除去,加入足量稀硫酸充分反应后,过滤,可得到纯净的铜粉;

故选B,A;

把混有氢气的二氧化碳气体通过足量的灼热的氧化铜,氢气和氧化铜反应生成铜和水而除去混合气体中的氢气;

故答案为:e;

向硫酸亚铁和硫酸铜混合溶液中加入足量铁粉,铁粉与混合溶液中的硫酸铜反应生成硫酸亚铁和铜,待完全反应后,过滤,则可得到纯净硫酸亚铁溶液;

故选C,A;

利用碳酸钠可与硫酸反应生成硫酸钠、二氧化碳气体和水,向混合物中滴加足量的稀硫酸后,蒸发,可得到纯净的硫酸钠晶体;

故选B,B.

单项选择题
单项选择题

My Space and other Web sites have unleashed a potent new phenomenon of social networking in cyberspace, (1) at the same time, a growing body of evidence is suggesting that traditional social (2) play a surprisingly powerful and under-recognized role in influencing how people behave.

The latest research comes from Dr. Nicholas A. Christakis, at the Harvard Medical School, and Dr. James H. Fowler, at the University of California at San Diego. The (3) reported last summer that obesity appeared to (4) from one person to another (5) social networks, almost like a virus or a fad. In a follow-up to that provocative research, the team has produced (6) findings about another major health (7) : smoking. In a study published last week in the New England Journal of Medicine, the team found that a person’s decision to (8) the habit is ply affected by (9) other people in their social network quit—even people they do not know. And, surprisingly, entire networks of smokers appear to quit virtually (10)

For (11) of their studies, they (12) of detailed records kept between 1971 and 2003 about 5,124 people who participated in the landmark Framingham Heart Study. Because many of the subjects had ties to the Boston suburb of Framingham, Mass. , many of the participants were (13) somehow—through spouses, neighbors, friends, co-workers—enabling the researchers to study a network that (14) 12,067 people.

Taken together, these studies are (15) a growing recognition that many behaviors are (16) by social networks in (17) that have not been fully understood. And (18) may be possible, the researchers say, to harness the power of these networks for many (19) , such as encouraging safe sex, getting more people to exercise or even (20) crime.

2()

A.resource

B.database

C.communication

D.intranet