问题 问答题

某烃的含氧衍生物可以作为无铅汽油的抗爆震剂,它的相对分子质量不超过100,含C的质量分数为68.2%,含H的质量分数为13.64%,其余为氧.请计算回答:

(1)该化合物的相对分子质量(分子量)是多少?

(2)该化合物的化学式(分子式)是______.

(3)若该化合物不能与钠反应产生氢气,红外光谱和核磁共振氢谱显示该分子中有4个甲基.请写出其结构简式:______.

答案

(1)氧元素的质量分数为1-68.2%-13.64%=18.16%,

N(C):N(H):N(O)=

68.2%
12
13.64%
1
18.16%
16
=5:12:1,即该有机化合物的最简式为C5H12O,

设其组成为(C5H12O)n,则(5×12+12×1+16)n<100,n为整数,解得n=1,

有机物的相对分子质量为5×12+12×1+16=88,

答:该化合物的相对分子质量为88;

(2)由(1)中的计算可知,该化合物的分子式为C5H12O,故答案为:C5H12O;

(3)该化合物不能与钠反应产生氢气,不含-OH,故有机物为醚,由于分子中有4个甲基,故其结构简式为

,故答案为:

阅读理解

阅读理解。

     Nearly everyone is shy in some ways. If shyness is making you uncomfortable, it may be time for a few

lessons in self-confidence. You can build your confidence by following some suggestions from doctors and

psychologists.

     Make a decision not to hold back in conversations. What you have to say is just as important as what other

people say. And don't turn down party invitations just because of your shyness.

     Prepare for yourself for being with others in groups. Make a list of the good qualities you have. Then make

a list of ideas, experiences, and skills you would like to share with other people. I think about what you would

like to say in advance. Then say it.

     If you start feeling self-conscious in a group, take a deep breath and focus your attention on other people,

Remember, you are not alone. Other people are concerned about the impression they are making, too.

     No one ever gets over being shy completely, but most people do learn to live with their shyness. Even

entertainers admit that they often feel shy. They work at fighting their shy feelings so that they can face the

cameras and the public. Just making the effort to control shyness can have many rewards. But perhaps the

best reason to fight shyness is to give other people a chance to know about you.

1. The main purpose of the article is to _____.

A. explain how shyness developed.

B. recommend ways of dealing with shyness

C. persuade readers that shyness is natural.

D. prove that shyness can be overcome

2. Which of these can you conclude from reading the article?

A. Shy people never have any fun.

B. Entertainers choose their work to fight shyness.

C. The attempt to overcome shyness is always successful.

D. The attempt to overcome shyness is always rewarding.

3. Who probably gives the suggestion for fighting shyness?

A. The author of the article

B. Shy men and women

C. Doctors and psychologists

D. Popular entertainers

填空题