问题 填空题

某学生设计了如下实验:

(1)该同学的实验目的是______;

(2)上图③操作步骤为______,④加入试剂为______;

(3)按此实验方案得到的NaCl固体中肯定含有______(填化学式)杂质;为了解决这个问题可以向过滤得到的滤液中加入适量的______;

(4)写出生成C的化学方程式______.

答案

(1)混合物A溶于水得到BaCl2和NaCl溶液,经过实验操作后得到BaCl2和NaCl,则实验目的是分离BaCl2和NaCl两种固体混合物,

故答案为:分离BaCl2和NaCl两种固体混合物;

(2)由溶液得到固体应用蒸发的操作分离,一般操作为蒸发浓缩、冷却结晶,过滤得到BaCO3沉淀,加入盐酸,BaCO3与盐酸反应生成BaCl2溶液,经蒸发结晶可得到BaCl2固体,

故答案为:蒸发,结晶;过量(足量)稀盐酸;

(3)溶液加过量Na2CO3溶液,过滤与NaCl和Na2CO3的混合溶液,加入盐酸,蒸发可得到NaCl固体,

故答案为:Na2CO3;稀盐酸;

(4)溶液加过量Na2CO3溶液,生成BaCO3沉淀,发生反应的化学方程式为BaCl2+Na2CO3=BaCO3↓+2NaCl,故答案为:BaCl2+Na2CO3=BaCO3↓+2NaCl.

阅读理解

阅读理解。

     As a child, I was really afraid of the dark and of getting lost. These fears were very real and caused me

some uncomfortable moments.

     Maybe it was the strange way things looked and sounded in my own room at night that scared me so

much. There was never complete darkness, but always a streetlight or passing car lights, which made clothes

on the back of a chair take on the shape of a wild animal. Out of the corner of my eye, I saw the curtains (窗

帘) seem to move when there was no wind. A very low sound in the floor would seem a hundred times louder

 than in the day. My imagination (想象) would run wild, and my heart would beat fast. I would lie very still so

that the"enemy(敌人)" would not discover me.

     Another of my childhood fears was that I would get lost, especially on the way home from school. Every

morning I got on the school bus right near my home. That was no problem. After school, though, when all the

buses were lined up along the street, I was afraid that I would get in the wrong one and be taken to some other

strange places. On school or family trips to a park or a museum, I wouldn't let the leaders out of my sight.

     Perhaps one of the worst fears of all I had as a child was that of not being liked or accepted by others.

Being popular was so important to me then, and the fear of not being liked was a serious one.

     One of the processes (过程) growing up is being able to realize and overcome our fears. Understanding the

things that scared us as children helps us achieve greater success later in life.

1. The author had _____ kind(s) of fears when she was a child.

A. one

B. two

C. three

D. none

2. _____ would scare the author at night.

A. Streetlight and car lights

B. Wild animals and enemies

C. Moving curtains and wind

D. Strange sights and sounds

3. When she went to some other places, she would _____.

A. walk away without others

B. take a bus by herself

C. follow others closely

D. make sure not to take a wrong bus

4. Which of the following would be possibly true when she was a child?

A. She was usually popular among people.

B. She was always the leader of the others.

C. She always' got poor grades.

D. She was not at all liked by others.

5. The underlined word "overcome" means "_____" in Chinese.

A. 接受

B. 忍受

C. 信服

D. 克服

选择题