问题 填空题

劣质奶粉通过添加三聚氰胺提高蛋白质的含氮量.三聚氰胺为白色晶体,低毒,常温稳定,高温可分解.牛奶呈中性或微酸性.目前,我国生产三聚氰胺多采用尿素为原料.

反应原理:6CO(NH2

硅胶
380℃
1个三聚氰胺分子+6NH3↑+3CO2

试回答:

(1)三聚氰胺的化学式为 ______,上述反应的反应类型是 ______.

(2)向三聚氰胺的水溶液中滴加酚酞试液呈红色,说明其水溶液呈 ______性.

答案

(1)根据质量守恒定律和化学方程式可得,三聚氰胺的化学式中应含有C的个数为:6-3=3,应含有O的个数为:6-2×3=0,应含有H的个数为:6×2×2-6×3=6,应含有N的个数为:6×2-6=6;故三聚氰胺的化学式为:C3H6N6

②上述反应是一种化合物在特定条件下(如加热、通直流电、催化剂等)分解成二种以上较简单的单质或化合物的反应,属于分解反应;

(2)因为酚酞试液遇碱变红色,所以向三聚氰胺的水溶液中滴加酚酞试液呈红色,说明其水溶液呈碱性.

故答案为:(1)C3H6N6;分解反应;

(2)碱.

多项选择题
阅读理解

阅读理解。

     In modern society there is a great deal of argument about competition. Some value it highly, believing

that it is responsible for social progress and prosperity. Others say that competition is bad; that it sets one

person against another; that it leads to unfriendly relationship between people.

     I have taught many children who held the belief that their self-worth relied (依赖) on how well they

performed at tennis and other skills. For them, playing well and winning are often life-and-death affairs.

In their single-minded pursuit (追求) of success, the development of many other human qualities is sadly

forgotten.

     However, while some seem to be lost in the desire to succeed, others take an opposite attitude. In a

culture which values only the winner and pays no attention to the ordinary players, they strongly blame

competition. Among the most vocal are youngsters who have suffered under competitive pressures from

their parents or society. Teaching these young people, I often observe in them a desire to fail. They seem

to seek failure by not trying to win or achieve success. By not trying, they always have an excuse: " I may

have lost, but it doesn't matter because I really didn't try." What is not usually admitted by themselves is the

belief that if they had really tried and lost, that would mean a lot. Such a loss would be a measure of their

worth. Clearly, this belief is the same as that of true competitors who try to prove themselves. Both are

based on the mistaken belief that one's self-respect relies on how well one performs in comparison with

others. Both are afraid of not being… Only as this basic and often troublesome fear begins to dissolve (缓解)

can we discover a …meaning in competition.

1. What does this passage mainly talk about?

A. Competition helps to set up self-respect.

B. Opinions about competition are different among people.

C. Competition is harmful to personal quality development.

D. Failures are necessary experience in competition.

2. Why do some people favor competition according to the passage?

A. It pushes society forward.

B. It builds up a sense of duty.

C. It improves personal abilities.

D. It encourages individual efforts.

3. The underlined phrase "the most vocal" in Paragraph 3 means ________.

A. those who try their best to win

B. those who value competitionj most highly

C. those who are against competition most strongly

D. those who rely on others most for success

4. What is the similar belief of the true competitors and those with a "desire to fail"?

 A. One's worth lies in his performance compared with others.

B. One's success in competition needs great efforts.

C. One's achievement is determined by his particular skills.

D. One's success is based on how hard he has tried.

5. Which point of view may the author agree to?

A. Every effort should be paid back.

B. Competition should be encouraged.

C. Winning should be a life-and-death matter.

D. Fear of failure should be removed in competition.