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问题 选择题

对于反应3Br2+6NaOH＝5NaBr+NaBrO3+3H2O，以下叙述正确的是

A．Br2是氧化剂，NaOH是还原剂

B．氧化产物与还原产物的物质的量的比为5∶1

C．Br2既是氧化剂又是还原剂

D．每生成1mol的NaBrO3转移6mol的电子

答案

答案：C

题目分析：A、根据方程式可知，溴元素的化合价从0价部分升高到＋5价，失去5个电子，部分从0价降低到－1价，得到1个电子，因此单质溴既是氧化剂又是还原剂，A不正确；B、溴酸钠是氧化产物，溴化钠是还原产物，所以氧化产物与还原产物的物质的量的比为1∶5，B不正确；C、Br2既是氧化剂又是还原剂，C正确；D、每生成1mol的NaBrO3转移5mol的电子，D不正确，答案选C。

选择题
、对“十·一”黄金周7天假期去某景区旅游的人数进行统计，每天旅游的人数统计如下表：其中众数和中位数分别是（    ）
日期
10月1日
10月
2日
10月
3日
10月
4日
10月
5日
10月
6日
10月
7日
人数（单位：万）
1.2
2
2. 5
2
1.2
2
0.6
A、1.2， 2           B、2，2.5       C、2，2          D、1.2， 2.5
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单项选择题

Human beings can see the spatial relations among objects by processing information conveyed by light. Scientists trying to build computers that can detect spatial relations by the same kind of process have so far designed and built stationary machines. However, these scientists will not achieve their goal until they produce such a machine that can move around in its environment.
Which of the following, if true, would best support the prediction above

A．Human beings are dependent on visual cues from motion in order to detect spatial relations.

B．Human beings can often easily detect the spatial relations among objects, even when those objects are in motion.

C．Detecting spatial relations among objects requires drawing inferences from the information conveyed by light.

D．Although human beings can discern spatial relations through their sense of hearing, vision is usually the most important means of detecting spatial relations.

E．(E) Information about the spatial relations among objects can be obtained by noticing such things as shadows and the relative sizes of objects.
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