问题 填空题

同学以“积木游戏”来建立物质之间的联系.A~F为初中常见的物质,其中至少有一种为无色气体.

(1)同学们用五块积木A~E做游戏.把E放在A、D之上,则A、B、C、D、E能够逆时针循环转化.已知:B、C、E为单质,A为红色固体,则C是______,E是______,A转化为B的化学方程式为______.

(2)同学们用另外六块积木A~F代表不同化合物继续做游戏.大家发现A、B、C、D能够逆时针循环转化,E和F能够相互转化,A、B、C、E、F、D也可逆时针循环转化.已知:A中两元素的质量比为3:8,且A、D、F含两种相同元素,则D的化学式为______,A转化为B的化学方程式为______,F转化为E的化学方程式为______.

答案

(1)由题中已知B、C、E为单质,A为红色固体,可推测A为氧化铁,由A、B、C、D、E能够逆时针循环转化,推断B为单质铁;铁与酸可得单质C为氢气;氢气在氧气中燃烧可得物质D为水;水通电分解可得单质E为氧气;E物质氧气再与铁生成氧化铁;因此,C是H2;E是O2;A转化为B的化学方程式为3CO+Fe2O3

 高温 
.
 
3CO2+2Fe;

(2)由题中已知:A中两元素的质量比为3:8,且A、D、F含两种相同元素,可推测A为二氧化碳,利用A、B、C、D能够逆时针循环转化,E和F能够相互转化,A、B、C、E、F、D也可逆时针循环转化规律,可推测D、F为碳酸盐,D可为碳酸钙;由较为熟悉的二氧化碳与氢氧化钙反应生成碳酸钙和水,可猜想B为水,根据ABCD的转化,可猜想C为氢氧化钙;由F为碳酸盐能与E相互转化,E可由C氢氧化钙转化生成,根据氢氧化钙与碳酸钠生成氢氧化钠可猜想E为氢氧化钠,则把F定为碳酸钠;因此建立出以下的物质转化关系:二氧化碳→水→氢氧化钙→氢氧化钠→碳酸钠→碳酸钙→二氧化碳,经大、小循环的验证此转化关系成立;

故D的化学式为CaCO3;A转化为B的化学方程式为Ca(OH)2+CO2=CaCO3↓+H2O;F转化为E的化学方程式为Na2CO3+Ca(OH)2=2NaOH+CaCO3↓;

故答案为:

(1)H2;O2;3CO+Fe2O3

 高温 
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3CO2+2Fe;

(2)CaCO3;Ca(OH)2+CO2=CaCO3↓+H2O;Na2CO3+Ca(OH)2=2NaOH+CaCO3↓.

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If there is one thing scientists have to hear, it is that the game is over. Raised on the belief of an endless voyage of discovery, they recoil from the suggestion that most of the best things have already been located. If they have, today’s scientists can hope to contribute no more than a few grace notes to the symphony of science.

A book to be published in Britain this week, The End of Science, argues persuasively that this is the case. Its author, John Horgan, is a senior writer for Scientific American magazine, who has interviewed many of today’s leading scientists and science philosophers. The shock of realizing that science might be over came to him, he says, when he was talking to Oxford mathematician and physicist Sir Roger Penrose.

The End of Science provoked a wave of denunciation in the United States last year. "The reaction has been one of complete shock and disbelief, "Mr. Horgan says.

The real question is whether any remaining unsolved problems, of which there are plenty, lend themselves to universal solutions. If they do not, then the focus of scientific discovery is already narrowing. Since the triumphs of the 1960s—the genetic code, plate tectonics, and the microwave background radiation that went a long way towards proving the Big Bang—genuine scientific revolutions have been scarce. More scientists are now alive, spending more money on research, that ever. Yet most of the great discoveries of the 19th and 20th centuries were made before the appearance of state sponsorship, when the scientific enterprise was a fraction of its present size.

Were the scientists who made these discoveries brighter than today’s That seems unlikely. A far more reasonable explanation is that fundamental science has already entered a period of diminished returns. "Look, don’t get me wrong," says Mr Horgan. "There are lots of important things still to study, and applied science and engineering can go on for ever. I hope we get a cure for cancer, and for mental disease, though there are few real signs of progress.

There have not been many genuine scientific revolutions in the past few decades because()

A. there have been decreased returns in the research of fundamental science

B. there are too many important things for scientists to study

C. applied science and engineering take up too much time and energy

D. today’s scientists are not as intelligent as those in the past