问题 选择题

配制下列溶液的操作使溶液浓度偏高的是()

A.等体积18 mol·L-1浓H2SO4和蒸馏水混合配制9 mol·L-1 H2SO4

B.配制500 mL 6 mol·L-1盐酸,容量瓶未干燥就配制溶液

C.配制1 mol·L-1 NaOH溶液,已定容后,再正倒摇匀,竖直后发现液面稍低于刻度线

D.配制好的0.2 mol·L-1 NaCl溶液从容量瓶转移到刚用蒸馏水洗净的清洁玻璃塞细口瓶中

答案

答案:A

因浓硫酸与等体积水相混体积会缩小,故所配H2SO4大于9 mol·L-1;因需往容量瓶内加水定容,故容量瓶未干燥不影响所配溶液的浓度;定容后,发现液面稍低于刻度线是正常现象,这是由于液体分子间有间隔及液体因沾附在瓶塞处而滞留,结果正常;因细口瓶内有水会使所配NaCl溶液浓度降低。

阅读理解

As a volunteer(自愿者) teacher, I traveled a long way to a small village school in Longzhou, Guangxi. On my way there, I thought about the village, the school and the childrenn there. However, my heart sank when I arrived there. It wasn't what I expected. It didn't look like a school at all! The school had only three rooms, one for Grades 1, 2 and 3, and the other for Grades 4, 5 and 6. There was a third one for me.

  The children welcomed me warmly on my first day. They asked me a lot of questions, and I told them stories about myself and my life in Shanghai. The next day, I gave them a test to find out their level(水平). To my surprise, though the test was very easy, over half of the students failed it, yet they all wanted to learn new things. I knew they needed me.

I was busy preparing lessons and reading test papers every night. I enjoyed teaching these lovely and hard-working children, and I could see that they were making progress(进步) with my help. I have also learned a lot from them. I understand their level is becoming higher and higher, and we are good friends now.

I worked in Longzhou for a year. I'm very happy, and the experience(经历) is very useful to me. I love the small village and the children. In fact, I would like to continue working here.

小题1:How many grades are there in the school?

A.2

B.4

C.5

D.6小题2:The writer came from        .

A.Longzhou

B.Guangxi

C.Shanghai

D.Beijing小题3:What does the writer think of working in the school?      .

A.Boring

B.Useful

C.Careful

D.Surprising小题4:According to the passage. The writer        .

A.was sorry for the school

B.worked hard to teach the children

C.don’t want to work in the school

D.left the school in a short time

选择题