问题 选择题

小张同学用下图所示的装置测定空气中氧气的含量,实验后发现所测定氧气的体积分数大于1/5。下列是小张同学对此实验误差的一些想法,你认为合理的是

A.将红磷点燃伸入集气瓶时速度较慢,瓶内气体受热膨胀逸出

B.弹簧夹未夹紧

C.实验中红磷的量可能不足,没有将瓶内的氧气消耗完全

D.反应后未能完全冷却至室温就打开止水夹

答案

AB

题目分析:根据实验操作过程和注意事项分析判断。

A、将红磷伸入集气瓶的速度过慢,会导致瓶内气体受热膨胀而逸出,瓶内气体减少,故等反应完毕冷却后会使进入的水的体积大于五分之一,正确;

B、弹簧夹未夹紧,也会在红磷燃烧时,导致瓶内气体受热膨胀而逸出,故等反应完毕冷却后会使进入的水的体积大于五分之一,正确;

C、如果红磷的量不足,燃烧时就无法将瓶内氧气全部消耗完,则水倒吸入装置内的量就占不到其容积的五分之一,错误;

D、装置未冷却至室温就打开弹簧夹,由于此时瓶内温度较高,气压还没完全降下来,故水倒吸入装置内的量就占不到其容积的五分之一,错误。故选AB

点评:熟练掌握用红磷测定空气里氧气含量的实验原理、操作步骤、实验现象、实验结论和注意事项等,是解题的关键。

阅读理解

It was a quiet village in which there was a military camp (军营). It was far from the towns and cities and there were some high mountains around. Of course it was a good place for training the new soldiers. But it was difficult for the young men to go outside. Mr. White, an officer of forty, was strict with them and he hardly let them leave the camp.

Once Mr. White was ill in bed. He couldn’t work and a young officer, Mr. Hunt, began to train the new soldiers instead of him. He knew the young men well and let nine soldiers go to the nearest town to have a holiday. But night fell and none came back to the camp. He was worried about it and stood at the gate. It was five to twelve when Mr. Hunt decided to go to the town and see what was happening to the young men. He started the car quickly and set off. At that moment the nine soldiers came back. It seemed they drank wine. Of course they found the officer was angry.

“I’m sorry, sir,” said the first soldier. “I left the town on time. But something was wrong with my bus on my way here. I had to buy a horse and made it run fast. Bad luck! It died and I had to run back.”

And the other seven soldiers said they were late for the same reasons. It was the last soldier’s turn. He said, “I’m sorry, sir. I got on a bus on time, but....”

Having heard this, the officer became even angrier and stopped him at once. He called out, “If you say something was wrong with your bus, I’ll punish you at once!”

“No, no, sir,” said the young man. “My bus was all right, but the dead horses were in its way!”

小题1:The military camp was built in the village to ________.

A.stop the soldiers from going to towns

B.stop the soldiers from meeting their friends

C.train the new soldiers

D.make the young men live quietly小题2:Mr. Hunt let the nine soldiers have a holiday because ________.

A.he was kind to them

B.they felt lonely

C.they had something important to do

D.they were the best of all小题3:The young officer was worried because ________.

A.a traffic accident had happened

B.he was afraid something happened to the nine soldiers

C.the nine soldiers would come back

D.the nine soldiers drank too much in the town小题4:Which of the statements do you think is true?

A. You’ll believe only the last soldier.

B. The officer believed the nine soldiers.

C. You’ll believe none of the nine soldiers.

D. The officer wouldn’t punish his soldiers.

单项选择题 A1/A2型题