问题 选择题

联氨(N2H4)可作火箭的燃料,燃烧时反应为2N2H4+2NO2=3N2+4H2O.下列说法错误的是(  )

A.此反应是氧化还原反应

B.反应瞬间产生大量高温气体,推动火箭飞行

C.N2H4的摩尔质量为32g/mol

D.此反应中N2H4作氧化剂

答案

A、此反应中N元素有化合价的变化,所以是氧化还原反应,故A正确;

B、该反应是一个放热反应,反应瞬间产生大量高温气体,推动火箭进行,故B正确;

C、N2H4的分子量是32,所以其摩尔质量为32g/mol,故C正确;

D、该反应2N2H4+2NO2=3N2+4H2O中,N2H4→N2,N元素由-2价→0价,失电子,所以N2H4作还原剂,故D错误.

故选D.

阅读理解

阅读理解。

     He wishes the holiday season would end already. His back aches, his red suit feels like a spacesuit, his

cheeks have gone tight from smiling for 12 hours-and still the kids keep coming and coming, like ants at a

picnic. As Christmas becomes more commercialized (商业化) across the U. S. And Canada, so must Santas.

As the holiday begins earlier each year, so must its spokesmen.

     The questions from children these days are harder than ever. Now, with thousands of children expecting

a father or mother serving in Iraq or Afghanistan, the questions are as heart-breaking as they are unanswerable. For example, "Can you please bring Daddy home from the war in time for Christmas morning?"

     Santas also have a pretty good chance of getting sued (指控). A professional Santa Claus in Canada told a

story: A Santa had a girl on his knee, and he commented, "You have nice eyes and nice hair." The girl later

said it was sexual harassment (骚扰). When a Santa feels anxious, he often shows it in the same ways ordinary people do: The Santas were always seen to hang around at the dinner table when the show ended. Many of them just sleep in bed for several days and don't see other children again.

1. In the first paragraph, "spokesmen" refers to _____.

A. businessmen

B. political leaders

C. organisers of the activities

D. Santa Clauses

2. The passage implies that the job of Santa Claus is _____.

A. well-paid

B. very hard

C. worth doing

D. dangerous

3. According to the third paragraph, Santas may sometimes be blamed for _____.

A. doing something against the law

B. hanging around the dinner table

C. being lazy and sleeping in bed for days

D. not playing their roles as expected

4. What would be the best title for the passage? 

A. Christmas: Not a Good Festival for Santas

B. Is Santa Claus Really Alive?

C. A Christmas Story

D. What Does Santa Claus Do for Children?

单项选择题