问题 实验题

有一瓶澄清的溶液.其中可能含有NH4+, K+, Mg2+, Ba2+, Al3+, Cl-, I-, NO3-, CO32-, SO42-中的几种。取该溶液进行以下实验。

(1)用pH试纸检验,表明溶液呈现强酸性,排除_______的存在。

(2)取出部分溶液,加入少量CCl4及数滴新制氯水,经振荡CCl4呈紫红色,排除___的存在。

(3)另取部分溶液,逐渐向其中加入NaOH溶液,使溶液从酸性逐渐变为碱性,滴加过程中和滴加完毕后,均无沉淀产生,则可排除_______的存在。取部分碱性溶液加热,有气体放出,该气体能使湿润的红色石蕊试纸变蓝。

(4)另取部分上述碱性溶液,向其中加入Na2CO3溶液,有白色溶液生成,证明________存在,又排除________存在。

(5)综上所述,该溶液中上述离子尚不能确定是否存在的是_______。

(6)若要确认(5)中相关离子,确认的实验方法是______________________________。

答案

(1)CO32-

(2)NO3-

(3)Mg2+、Al3+

(4)“略”

(5)“略”

(6)“略”

单项选择题
单项选择题

There is a difference between science and technology. Science is a method of answering (1) questions; technology is a method of solving practical problems. Science has to do with discovering the facts and relationships between (2) phenomena in nature and with establishing theories that (3) to organize these facts and relationships; technology has to do with tools, techniques, and (3) for applying the findings of science. Another (5) between science and technology has to do with the progress in each.

Progress in science (6) the human factor. Scientists, who seek to understand the universe and know the truth within the highest degree of (7) and certainty, cannot (8) their own or other people’s likes or dislikes or to popular ideas about the fitness of things. What scientists discover may shock or (9) people-as did Darwin’s theory of evolution. But even an unpleasant truth is (10) than likely to be useful; besides, we have the choice of refusing to believe it! But (11) so with technology; we do not have the choice of refusing to hear the sound produced by a supersonic aircraft flying overhead; we cannot refuse to breathe polluted air. (12) science, progress in technology must be measured (13) the human factor. The purpose of technology is to serve people—people (14) , not merely some people; and future generations, not merely those who presently wish to (15) advantage for themselves.

We are all familiar with the (16) use of technology. Many people blame technology itself (17) widespread pollution, resource depletion (枯竭) and even social decay in general—so much (18) the promise of technology is " (19) " That promise is a cleaner and healthier world. If wise applications of science and technology do not (20) a better world, what else will

2()

A.discernible

B.negligible

C.sustainable

D.observable