问题 选择题

锌锰电池以氢氧化钾溶液为电解液,电池总反应式为:Zn(s)+2MnO2(s)+H2O(l)=Zn(OH)2(s)+Mn2O3(s),下列说法错误的是(  )

A.电路中每通过0.2mol电子,锌的质量理论上减小6.5g

B.电池负极的电极反应式为Zn-2e-+2 OH-=Zn(OH)2

C.电池工作时,电流由正极通过外电路流向负极

D.碱性锌锰电池是二次电池

答案

A、由Zn(s)+2MnO2(s)+H2O(l)═Zn(OH)2(s)+Mn2O3(s)可知,65gZn反应转移电子为2mol,则6.5gZn反应转移0.2mol电子,故A正确;

B、负极失电子,发生氧化反应,所以负极的电极反应式为:Zn-2e-+2OH-=Zn(OH)2,故B正确;

C、电池工作时,电子由负极流向正极,电流由正极通过外电路流向负极,故C正确;

D、碱性锌锰电池是一次电池,不可以连续充放电,故D错误.

故选D.

阅读理解

阅读理解

     A friend of mine named Jim received an expensive car from his brother as a Christmas present. On Christmas Eve

when Jim came out of his office,a street urchin(顽童) was walking around the shining car. "Is this your car, Jim?" he

asked.

     Jim answered,"Yes,my brother gave it to me for Christmas." The boy was surprised." You mean your brother gave

it to you and it didn't cost you nothing? Boy, I wish..." He hesitated(犹豫).

     Of course Jim knew what he was going to wish for. He was going to wish he had a brother like that. But what the

boy said surprised Jim greatly.

     "I wish," the boy went on," that I could be a brother like that." Jim looked at the boy in surprise, then he said

again, "Would you like to take a ride in my car?"

     "Oh yes,I'd love that."

     After a short ride, the boy turned and with his eyes shining, said, "Jim, would you mind driving in front of my

house?"

     Jim smiled a little. He thought he knew what the boy wanted. He wanted to show his neighbours(邻居) that he

could ride home in a big car. But Jim was wrong again. "Will you stop where those two steps are?" the boy asked. 

     He ran up to the steps. Then in a short while Jim heard him coming back, but he was not coming fast. He was

carrying his little crippled(残疾) brother. He sat him down on the step and pointed to the car.

     "There she is, Buddy, just like I told you upstairs. His brother gave it to him for Christmas and it didn't cost him

a cent. And some day I'm going to give you one just like it...

1. The street urchin was very surprised when __________.

A. Jim received an expensive car

B. Jim told him about the car

C. he saw the shining car

D. he was walking around the car

2. From the story we can see the urchin __________.

A. wished to give his brother a car

B. wanted Jim's brother to give him a car

C. wished he could have a brother like Jim's

D. wished Jim could be a brother like that

3. The urchin asked Jim to stop his car in front of his house __________.

A. to show his neighbours the big car

B. to show he had a rich friend

C. to let his brother ride in the car

D. to tell his brother about his wish

4. We can infer(推断) from the story that __________.

A. Jim couldn't understand the urchin

B. the urchin had a deep love for his brother

C. the urchin wished to have a rich brother

D. the urchin's wish came true in the end

5. The best name of the name story is __________.

A. A Christmas Present

B. A Street Urchin

C. A Brother Like That

D. An Unforgettable Holiday Ride

单项选择题