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问题 推断题

（6分）下列A～D为初中化学常见物质，其中A为含有金属钠离子的盐，C为大理石的主要成分。它们之间存在下列关系：

（1）A的化学式             ；C的化学式             。

（2）D中一定含有的溶质是           。用化学方程式表示你判断的理由：

①                                    ；

②                                    。

（3）D还可能含有的溶质是                 。

答案

（6分）（1）Na2CO3       CaCO3  

（2）NaOH  CaO + H2O =Ca(OH)2   Ca(OH)2 +Na2CO3 =CaCO3 ↓+2NaOH  

（3）Ca(OH)2或Na2CO3  （每空1分，共6分）

分析：根据D是大理石的主要成分，所以D就是碳酸钙，A为钠盐且和B在水中反应生成碳酸钙，所以A为碳酸钠；碳酸钙高温会生成氧化钙和二氧化碳，所以B为氧化钙．

解：（1）D是大理石的主要成分，所以D就是碳酸钙，A为钠盐且和B在水中反应生成碳酸钙，所以A为碳酸钠；

（2）碳酸钙高温会生成氧化钙和二氧化碳，所以B为氧化钙；

氧化钙和水反应生成氢氧化钙，氢氧化钙和碳酸钠反应生成碳酸钙和氢氧化钠，所以D中一定含有氢氧化钠，发生反应的化学方程式为：CaO+H2O=Ca（OH）2，Ca（OH）2+Na2CO3=CaCO3↓+2NaOH；

（3）若氢氧化钙过量，则无色溶液D中还含有氢氧化钙；若碳酸钠过量，则无色溶液D中还含有碳酸钠．

故答案为：（1）Na2CO3，CaCO3；

（2）NaOH；CaO+H2O=Ca（OH）2，Ca（OH）2+Na2CO3=CaCO3↓+2NaOH；

（3）Ca（OH）2或Na2CO3．

单项选择题

Americans are often contrasted with the rest of the world in terms of material possessions. We are accused of being materialistic, gadget crazy. And, as a matter of fact, we have developed material things for some very interesting reasons. Lacking a fixed class system and having all extremely mobile population, Americans have become highly sensitive to how others make use of material possessions. We use everything from clothes to houses as a highly evolved and complex means of ascertaining each other’s status. Ours is a rapidly shifting system in which both styles and people move up or down. For example:
The Cadillac (卡迪拉克) ad men feel that not only is it natural but quite insightful of them to show a picture of a Cadillac and a well-turned out gentleman in his early fifties opening the door. The caption (标题) underneath reads, "You already know a great deal about this man. "
Following this same pattern, the head of a big union spends an excess of $100, 000 furnishing his office so that the president of United States Steel cannot look down on him. Good materials, large space, and the proper surroundings signify that the people who occupy the premises (建筑物及其周围所属土地) are solid citizens, that they are dependable and successful.
The French, English, and the Germans have entirely different ways of using their material possessions. What stands for the height of dependability and respectability with the English would be old-fashioned and backward to us. The Japanese take pride in often inexpensive but tasteful arrangements that are used to produce the proper emotional setting.
Middle East businessmen look for something else-family, connections, friendship. They do not use the furnishings of their office as part of their status system; nor do they expect to impress a client by these means or to fool a banker into lending more money than he should. They like good things, too, but feel that they, as persons, should be known and not judged solely by what the public sees.
One of the most common criticisms of American relations abroad, both commercial and governmental, is that we usually think in terms of material things. "Money talks," says the American, who goes on talking the language of money abroad, in the belief that money talks the same language all over the world. A common practice in the United States is to try to buy loyalty with high salaries. In foreign countries, this maneuver almost never works, for money and material possessions stand for something different there from they do in America.

It is implied in the passage that ______.

A. English people prefer old-fashioned things
B. Japanese pay more attention to emotional rather than material value of their furnishings
C. Middle East businessmen value friendship and don’t like good material things
D. the French and Germans use material possession in the same way as the English
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名词解释

《伏尔加河上的纤夫》
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