（2013天津）某研究性学习小组为了探究氢氧化钠溶液与稀硫酸是否_爱下问搜题

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问题选择题

（2013天津）某研究性学习小组为了探究氢氧化钠溶液与稀硫酸是否恰好完全反应，分别取少量反应后的溶液于试管中，用下表中的不同试剂进行实验。下列选项错误的是

选项	所用试剂	现象和结论
A	硫酸铜溶液	出现蓝色沉淀，则氢氧化钠过量
B	氯化钡溶液	出现白色沉淀，则硫酸过量
C	锌粒	有气泡产生，则硫酸过量
D	无色酚酞溶液	溶液不变色，则恰好完全反应

答案

BD

题目分析：硫酸和氢氧化钠溶液反应无明显现象，将一定量的硫酸和氢氧化钠混合后，存在着如下情况：恰好完全反应，溶液中的溶质只有硫酸钠，硫酸过量，溶液中的溶质有硫酸钠和硫酸，氢氧化钠过量，溶液的溶质有硫酸钠和氢氧化钠。硫酸钠也能与氢化钡反应生成硫酸钡沉淀，所以加入氯化钡溶液无论硫酸是否过量均有白色沆淀，酚酞在中性溶液和酸性溶液中都不变色，如果硫酸过量，滴加酚酞溶液也不变色，所以答案选BD.

问答题简答题

煤矿“一通三防”内容是指什么？

问答题

Children in any society are expected to learn to conform to a number of social rules and expectations if they are to become participants in the culture. (46)Among the rules that children in our society are expected to learn are that certain classes of adults (such as teachers and doctors) are addressed by titles, that males and females use separate restroom facilities, and that women but not men wear dresses. These are examples of social conventions. In the absence of such a shared norm, the acts are neither right nor wrong. For this reason, conventions may be said to be arbitrary. For example, (47)we could just as easily have students address teachers by first names as have them call teachers by their last names and formal titles of Mr. or Ms.
Conventions, however, serve an important function by providing predictability and order to social life. (48)Without social conventions it would be impossible to organize social institutions such as schools, and societies as organized systems could not exist. The arbitrariness of conventions makes their importance difficult for children to figure out. (49) It is not until some time in adolescence that children come to fully understand the function that these arbitrary conventions serve to provide predictability and order to our social interactions.
In contrast with issues of convention are matters of morality. Morality refers to issues of human welfare, justice, and rights that are a function of the inherent features of interpersonal relations. Because of this, the right and wrong of moral actions are not simply determined by social consensus or the views of authority. For example, it is not possible to hit another person with force and not hurt the other person. Similarly, it is not possible to steal something valuable from someone else and not cause the person to experience the sense of loss. A moral judgment about unprovoked harm ( "It is wrong to hit") would not be dependent on the existence of a socially agreed upon rule or standard but could be generated solely from the intrinsic effects of the act (i.e., hitting hurts). (50)Similar analyses could be done regarding a broader range of issues that would extend beyond direct harm to concerns for what it means to be just, compassionate, and considerate of the rights of others.