问题 填空题

如图,E为沾有Na2SO4溶液的滤纸,并加入几滴酚酞。A,B分别为Pt片,压在滤纸两端,R、S为电池的 电极。M、N是用多微孔的Ni制成的电极材料,它在碱性溶液中可以视为惰性电极。G为电流计,K为开关。C、D和电解池中都充满浓KOH溶液。若在滤纸中央点上一滴紫色的KMnO4溶液,打开K,接通电源一段时间后,C、D中有气体产生。

(1)R为_____(填“正”或“负”)极。

(2)A极附近溶液的现象是_____________,B极附近发生的电极反应式为__________________。

(3)滤纸上的紫色点向_____(填“A”或“B”)方移动。

(4)当C、D里的气体产生到一定量时,切断外电源并接通开关K,经过一段时间,C、D中气体逐渐减少,C 中的电极为___(填“正”或“负”)极,电极反应式为_____________________。

答案

(1)负

(2)溶液变红;4OH--4e-=2H2O+O2

(3)B

(4)负;2H2+4OH--4e-=4H2O

单项选择题

I remember my math teacher Mr. Young very well. He stood out because the kids made fun of him. He was missing one of his fingers, and always pointed at students with his middle finger.

I was not very good at English and math. No matter how hard I tried, I just could not figure out why I did not understand what all the other kids found so easy to learn.

One day, I was told that if I got one more E on my report card, I would be taken to the" big prison for kids".

I tried really hard for weeks. I just couldn’t understand how to make different parts of members into whole things.

The day before report cards were to come out, I knew that Mr. Young would give me an E ,just like he always did.

I went to Mr. Young and told him that the orphanage was going to send me to the big prison if I got another E on my report card. He told me there was nothing he could do;it would be unfair to the other kids if he gave me a better grade than I had actually earned.

I smiled at him and said, "Mr. Young, do you know how the kids make fun of you because you’re missing your finger" He looked at me, moved his mouth to one side and said nothing.

"They shouldn’t do that to you because you can’t help having a finger, Mr. Young. Just like I can’t help not being able to learn numbers and stuff like that. "I said.

The next day, when I got my report card, I tucked it into one of my books. While on the school bus, I opened it : Geography, B+ ; Mechanical Drawing, C- ; English, D- ; History, C- ; Gym, B+ ; Art, C ; Math, D-.

That math grade was the most favorite one I ever received. Because I knew that someone in the world finally understood what it was like for me to be missing a finger inside my head.

The underlined word"tucked" in the passage most probably means“()”.

A. stuck

B. listed

C. hid

D. copied

单项选择题