问题 问答题

如图是实验室制取气体的一些常见的装置.试回答:

(1)若用加热高锰酸钾制取氧气,可先用的装置(填序号,下同)______,反应的文字表达式为______,做该实验时,试管口要放一团棉花的作用是______,实验结束应______以防止水槽的水倒流入试管炸裂灼热的试管底,

(2)一氧化氮(NO)气体密度比空气大且难溶于水,在空气中容易发生下列反应:2NO+O2=2NO2,则收集一氧化氮气体时不能用的装置是(填序号)______.

(3)按图F所示做细铁丝在氧气中燃烧的实验,集气瓶中装少量水的目的是______该反应的文字表达式为______.

答案

(1)用加热高锰酸钾制取氧气,属于加热固体制取气体,可先用装置B作为发生装置;反应的文字表达式为高锰酸钾

加热
锰酸钾+二氧化锰+氧气;做该实验时,试管口要放一团棉花,以防止高锰酸钾粉末进入导管;实验结束应时,应先将导管从水槽中撤出,再熄灭酒精灯,以防止水槽的水倒流入试管炸裂灼热的试管底;

(2)一氧化氮气体难溶于水,在空气中容易发生下列反应2NO+O2=2NO2,则收集一氧化氮气体时只能选用排水法收集;

(3)做细铁丝在氧气中燃烧的实验时,集气瓶中需装少量水,目的是防止生成物溅落下来,使集气瓶炸裂;该反应的文字表达式为铁+氧气

点燃
四氧化三铁.

故答案为:(1)B;高锰酸钾

加热
锰酸钾+二氧化锰+氧气;防止高锰酸钾粉末进入导管;先将导管从水槽中撤出,再熄灭酒精灯;(2)DE(3)防止生成物溅落下来,使集气瓶炸裂;铁+氧气
点燃
四氧化三铁

单项选择题 A1型题
阅读理解

The Doll and the White Rose

I was walking around in a mall, when I saw a cashier hand this little boy some money back.The cashier said, "I'm sorry, but you don't have enough money to buy this doll.”The little boy seemed very disappointed.

I walked toward him and asked him who he wished to give this doll to. "It's the doll that my sister wanted so much for Christmas.She was sure that Santa Claus would bring it to her. But Santa Claus can't bring it to her where she is now. I have to give the doll to my mommy so that she can give it to my sister when she goes there."His eyes were so sad."My sister has gone to be with God.Daddy says that Mommy is going to see God very soon too, so I thought that she could take the doll with her to give it to my sister."

My heart nearly stopped.The little boy looked up at me and continued, "I told Daddy to tell Mommy not to go yet. I need her to wait until I come back from the mall."

I quickly reached for my wallet and said," Suppose we check again, just in case you do have enough money for the doll."

"OK, I hope I do have enough," he said.I put some of my money with his without him seeing and we started to count it. There was enough for the doll and even some spare money.

Surprisingly, the little boy cried, "Thank you God for giving me enough money!" Then he looked at me and added, "I asked last night before I went to sleep for God to make sure I had enough money to buy this doll, so that Mommy could give it to my sister. He heard me! I also wanted to have enough money to buy a white rose for my mommy, but I didn't dare to ask God for too much.But he gave me enough to buy the doll and a white rose ! "

Then I remembered two days before a local newspaper reported an accident in which a woman and a little girl were badly injured.The little girl died right away, and the mother was left in a critical state.Was this the family of the little boy?

Two days after I met the little boy, I read in the newspaper that the woman had passed away.I couldn't stop myself from going to the funeral. Teary-eyed, I felt that my life had been changed forever.

小题1:The boy wanted to buy the doll because____________.

A.he had always been eager for such a doll

B.Santa Claus didn't give him any Christmas gift

C.he would give it to his mother as a birthday surprise

D.he wanted to turn his sister's Christmas wish into reality小题2:We can learn from the story that__________.

A.the boy's sister died after staying in hospital for two weeks

B.the boy's family were all seriously injured in a car accident

C.the author gave the boy some extra money without his notice

D.the boy's mother always wished to receive a white rose on Christmas小题3:The story most probably conveys the message that .

A.a kind act can bring joy and hope to others

B.a gift is a perfect way to express love for others

C.losing a family member is a heavy blow to children

D.a religiou s belief can help one solve problems in his life