题干

向四支试管中分别加入少量不同的无色溶液进行如下操作,结论正确的是(   )

操作

现象

结论

A

滴加稀NaOH溶液,将红色石蕊试纸置于试管口

试纸不变蓝

原溶液中无NH4+

B

向溶液X 中先滴加稀硝酸,再滴加Ba(NO32溶液

出现白色沉淀

溶液X 中一定含有SO42

C

滴加氯水和CCl4,振荡、静置

下层溶液显紫色

原溶液中有I

D

用洁净铂丝蘸取溶液进行焰色反应

火焰呈黄色

原溶液中有Na+、无K+

A:A  

B:B  

C:C  

D:D

上一题 下一题 0.0难度 选择题 更新时间:2019-03-14 10:39:07

答案(点此获取答案解析)

C

同类题3

根据短文理解,选择正确答案。

    When other nine-year-old kids were playing games, she was working at a petrol station. When other teens were studying or going out, she struggled to find a place to sleep on the street. But she overcame these terrible setbacks to win a highly competitive scholarship and gain entry to Harvard University. And her amazing story has inspired a movie, "Homeless to Harvard: The Liz Murray Story" shown in late April.

    Liz Murray, a 22.year-old American girl, has been writing a real-life story of willpower and determination. Liz grew up in the shadow of two drug-addicted parents. There was never enough food or warm clothes in the house. Liz was the only member of the family who had a job. Her mother had AIDS and died when Liz was just l5 years old. The effect of that LOSS became a turning point in her life. Connecting the environment in which she had grown up with how her mother had died,she decided to do something about it.

    Liz went back to school. She threw herself into her studies, never telling her teachers that she was homeless. At night, she lived on the streets. ".What drove me to live on had something to do with understanding, by understanding that there was a whole other way of being. I had only experienced a small part of the society,'' she wrote in her book Breaking Night.

    She admitted that she used envy to drive herself on. She used the benefits that come easily to others, such as a safe living environment, to encourage herself that "next to nothing could hold me down".

    She finished high school in just two years and won a full scholarship to study at Harvard University. But Liz decided to leave her top university a couple of months earlier this year in order to take care of her father, who has also developed AIDS."I love my parents so much. They are drug addicts. But I never forget that they love me all the time."

    Liz wants moviegoers to come away with the idea that changing your life is "as simple as making a decision".