问题 填空题

A~D都是初中化学中的常见物质,纯净的A在常温下为无色、无味的液体,B、C分别为气态单质,它们有如图所示的转化关系(反应条件、其它反应物及产物均已略去).回答下列问题:

(1)写出下列物质的化学式:A______; B______;

(2)写出“A→B+C”的化学方程式______.

答案

    由于A为无色无味的液体,我们学过的内容中有H2O和H2O2,而对应的反应产物为两种气体单质,就应该是H2和O2,至于BC与H2和O2的对应现在还需要进一步分析.由于B可以转化为D,而D能够再次和C反应生成A.可以试想:假如B是氢气,那B对应的产物为什么,且该物质能够与B(O2)能够反应,肯定是可燃性的物质,我们学过H2转化成的物质具有可燃性的.所以B可能是O2,这样B就可以转化为金属氧化物,而金属氧化物可以和C(H2)发生置换反应从而得到A(H2O).

所以A H2O;B O2;C H2.至于D应该是金属氧化物(氧化铜、氧化铁的能够都可以).

故答案:(1)H2O;  O2

(2)2H2O

 通电 
.
 
2H2↑+O2↑.

阅读理解

What’s the most important thing for you to have in your life? Somebody mentions hard-work, others suggest knowledge, love and luck.

If you arrange the 26 English letters alphabetically(按字母表的顺序)and use numbers to represent each of them, for example, 1 for a, 2 for b, 3 for c…, you can change an English word into a number. So hard-work becomes 8+1+18+4+23+15+18+11="98," meaning 98 is its mark; knowledge: 11+14+15+23+12+5+4+7+5="96," while love :12+15+22+5="54," and luck : 12+21+3+11="47," a small mark. None of these words can give one a full mark. What about money or prayer(祈祷)? They can’t , either.

Then what else? Don’t be worried. You can always find an answer to a problem in your life, when you change your way of looking at things or doing things, or your attitude(态度).Yes, attitude is the word. See for yourself: attitude:1+20+20+9+20+21+4+5=100,a full mark.

Different attitudes lead to different courses of life. Most times people hope for a better life. It is possible that one will have a change for the better after one has changed one’s attitude.

When you change your manner and became friendly towards others, you’ll meet more smiling faces towards you. In the same way, if you take a positive(积极地)attitude towards failure(失败),you’ll find it’s also rewarding though it has caused you losses.

小题1:In the writer’s opinion , what is the most important things in a person’s life?

A.Hard-work.

B.Knowledge.

C.Money.

D.Attitude.小题2:According to the passage, if you meet with problems, the best way out is to _________.

A.ask for help from others

B.say your prayers to God

C.change your attitude

D.try maths-solving methods小题3:From the passage we can learn that ______________.

A.diffrent attitudes come from different courses of life.

B.mathematics can solve every problem easily in our daily life

C.failure sometimes can bring you good if you take a positive attitude

D.none of the English words except “attitude” equals to 100 or more

单项选择题