问题 实验题

实验室有一瓶保管不当的试剂(如图),其残缺的标签中只剩下“Na”和“10%”字样.已知它是无色液体,是初中化学常用的试剂.小强和小华同学很感兴趣,决定对其成分进行探究:

【提出问题】这瓶试剂可能是什么溶液呢?

(1)【交流讨论】根据受损标签的情况判断,这瓶试剂不可能是 _________

A.酸       B.碱      C.盐

【查阅资料】

①初中化学常见的含钠化合物有NaCl、NaOH、Na2CO3、NaHCO3

②Na2CO3和NaHCO3溶液都呈碱性.

③测定室温(20℃)时,四种物质的溶解度的数据如下: 

(2)【作出猜想】①可能是_________ 溶液;②可能是Na2CO3溶液;③可能是NaCl.

(3)【设计并实验】

①小强用洁净的玻璃棒蘸取该溶液滴在pH试纸上,测得PH>7,这瓶试剂不可能是 _________

②小强为了检验该溶液是NaOH溶液还是Na2CO3溶液,他又进行了如下实验:

答案

(1)【交流讨论】A

(2)【作出猜想】NaOH

(3)【设计并实验】

   ①NaCl;

  ② 

阅读理解

Technology has utterly transformed our ability to communicate with each other. Linking to each other both literally and figuratively, many of us connect through cell phones, email, instant messaging, blogs, and networking web sites, yet we may be less connected to each other than we think.

According to a study, Americans are becoming increasingly socially isolated. The study reveals, for example, that one quarter of Americans say that they have no one to discuss important personal issues with, and that the number of close friends that American have has dropped from three to two. Meanwhile, the Boston Globe reports that this spreading isolation is experienced more sharply among those with less education, people of color, and older Americans. Unsurprisingly, those who are young, white, and well educated tend to have stronger social networks.

From my own experience I have to say that I’ve never felt more connected, thanks to a web of friends, family, and colleagues. One of my closest friends is someone I met through an online discussion group who lives hundreds of miles away from me. We have met face-to-face only twice, yet our regular electronic correspondence and cell phone calls sustain our close friendship. And, speaking of blogging, my blog has introduced me to people I would never have met otherwise and has led to enduring and important friendships.

On the other hand, I recently saw a scene unfold that proved to me how deeply disconnected we as Americans have become. I had just wrapped up a presentation on mediation at a family therapy(治疗) center. As I was leaving, I noticed a mother and her teenage son who had just completed their session with their family therapist(临床医学家). After making their next appointment, they both took out their cell phones, placed calls, and began loud conversations with whoever was on the other end. I walked out behind them to the parking lot to my car. They both jumped into their SUV, and, as I saw them drive off, they were still talking on their cell phones.

But, alas, not to each other.

51. What does the passage lead you to believe?

A. Americans are more socially connected today.

B. Americans are more socially isolated today.

C. Technology plays a bigger role in American society.

D. Americans don’t make good use of technology.

52. Which of the following has nothing to do with the isolation among Americans?

A. Age.              B. Education.                C. Skin color.               D. Sex.

53. The author himself _______.

A. has a wider range of friends because of technology

B. has failed to take advantage of technology

C. can only find true friendship through the Internet

D. can’t make true friends in actual life

54. What is true about the mother and son in the passage?

A. They came for therapy in the same car.

B. They were quite close to each other.

C. There was not much communication between them.

D. They preferred talking to each other on cell phones.

55. The author probably feels ________ with the mother and son.

A. puzzled         B. disappointed       C. amused                 D. surprised

单项选择题