问题 选择题

下列实验的操作、现象和解释或结论都正确的是

 操作现象解释或结论
A向装有Fe(NO3)2溶液的试管中加入几滴稀H2SO4溶液颜色基本不变Fe(NO3)2与H2SO4不反应
B向饱和Na2CO3溶液中通入足量CO2溶液变浑浊析出了NaHCO3晶体
C将Al2(SO4)3溶液蒸干有白色固体生成Al3++3H2OAl(OH)3↓+3H+
D将Na放入CuSO4溶液中有红色固体析出2Na+Cu2+=Cu+2Na+
 

答案

答案:B

题目分析:A.向装有Fe(NO3)2溶液的试管中加入几滴稀H2SO4,就相当于在FeSO4中滴加HNO3。由于Fe2+有还原性,而HNO3有氧化性,二者会发生氧化还原反应:3Fe2++4H++NO3-=3Fe3++NO↑+2H2O。溶液会因含有Fe3+变为黄色。错误。B.向饱和Na2CO3溶液中通入足量CO2,发生反应:Na2CO3+CO2+H2O= 2NaHCO3↓。由于NaHCO3的溶解度比Na2CO3小。所以会结晶析出,而使溶液变浑浊。正确。C.将Al2(SO4)3溶液蒸干, Al2(SO4)3是强酸弱碱盐水解产生硫酸和氢氧化铝。由于硫酸没有挥发性,所以二者会重新反应得到Al2(SO4)3。当溶液蒸干后得到的白色固体就是Al2(SO4)3。错误。D.将Na放入CuSO4溶液中,由于Na非常活泼,很容易与溶液中的溶剂水发生反应:2Na+2H2O=2NaOH+H2↑,产生的NaOH再与CuSO4发生复分解反应2NaOH+ CuSO4=Cu(OH)2↓+Na2SO4.因此不会产生黄色固体。反应原理也错误。

阅读理解

I live on the twelfth floor of a building. One afternoon I was coming home from a friend’s house. It was just after four o’clock. I got quickly into the lift and pressed Button12.

The lift started to go up, but very slowly . And then, half way up, it suddenly stopped between two floors. I couldn’t understand it. I pressed all the buttons from 1to 14. I called for help very loudly. But nobody answered.

Then suddenly the light went out, and I was alone in the dark. I started to cry and beat the walls of the lift. I cried and cried until I had no voice left. Then, I felt hopeless, and pressed all the buttons with my open hands. And all at the same time, there was a bell far away . It rang and rang. It was the fire alarm(火灾警报). I thought the whole building was on fire. I said to god quietly, “Just get me out of here. I’ll never be bad again.”

Just then, I realized the lift was moving very slowly . On the ground floor it stopped, and the doors opened. A man was standing there. “How long have you been there? It is good that you pressed the alarm bell. But haven’t you learned to read at your school?” He pointed at a small piece of paper on the wall beside the lift. It said: “Attention: This lift will be stopped for repairs between 4pm and 5pm on Thursday March 13.”

小题1:What happened to the lift?

A.It had a fire accident.

B.It stopped half way.

C.It was turned off by the writer.

D.It moved fast up to the top floor.小题2:As the situation went on , the writer became________________.

A.more and more sacred.

B.calmer and calmer.

C.more and more bored.

D.clearer and clearer.小题3:Why did a bell ring from far away.

A.The lift was to start again.

B.The repair worker rang the lift alarm.

C.The building was on fire.

D.the writer pressed the lift alarm bell.小题4:Who most probably made the lift move again and go down to the ground to the ground floor?

A.The writer.

B.The writer’s friend.

C.The man.

D.The writer’s father.小题5:After reading the paper, the writer realized that he/she had _______.

A.escaped from a fire accident

B.made a silly mistake.

C.visited a dishonest friend

D.pressed a wrong button.

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