问题 填空题

(4分)现有四种试剂:①新制Cu(OH)2悬浊液;②浓硝酸;③AgNO3溶液;④碘水。

为了鉴别下列四瓶无色溶液,请你选择合适的试剂,将其序号填入相应的括号中。

(1)葡萄糖溶液                              (2)食盐溶液              

(3)淀粉溶液                                (4)鸡蛋清溶液         

答案

(4分,每空1分)①;③;④;②

题目分析:葡萄糖中含有醛基,可以用新制Cu(OH)2悬浊液鉴别,答案选①;食盐能和硝酸银溶液反应生成白色沉淀,所以答案选③;淀粉和单质碘能发生显色反应,所以答案选④;浓硝酸可以使蛋白质发生显色反应,呈黄色,据此可以鉴别蛋白质,答案选②。

点评:进行物质的检验时,要依据物质的特殊性质和特征反应,选择适当的试剂和方法,准确观察反应中的明显现象,如颜色的变化、沉淀的生成和溶解、气体的产生和气味、火焰的颜色等,进行判断、推理、验证即可。

问答题
单项选择题

Passage Four

Adam Smith was the founder of economics as a distinct field of study. He wrote only one book on the subject — The Wealth of Nations, published in 1776. Smith was 53 years old at the time. His friend David Hume found the book such hard going that he doubted many people would read it. But Hume was wrong — people have been reading it for more than 200 years now.
The Wealth of Nations, in Smith’s view, was the result not of accumulating gold or silver, as many of that time believed, but of ordinary people working and trading in free markets. To Smith, the remarkable thing about the wealth produced by a market economy is that it does not result from any organized plan, rather, it is the unintended outcome of the actions of many people, each of whom is pursuing the incentives the market offers with his or her own interests in mind.
"It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest, every individual is continually exerting himself to find out the most advantageous employment for whatever capital he can command. By directing that industry in such a manner as its produce may be of the greatest value, he intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was a part of his intention".
Much of the discipline of economics as it has developed over two centuries consists of elaboration of ideas found in Smith’s work. The idea of the "invisible hand" of market incentives that channels people’s efforts in directions that are beneficial to their neighbors remains one of the most durable of Smith’s contributions.

Which of the following statements is true

A.Adam Smith was an economist.

B.Adam Smith wrote some books on economics.

C.David Hume was the co-author of the Wealth of Nations.

D.the Wealth of nations was published in 1976.