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问题 选择题

已知Fe3O4可表示成（FeO·Fe2O3），水热法制备Fe3O4纳米颗粒的总反应为：3Fe2++2S2O+O2+4OH－=Fe3O4+S4O+2H2O，下列说法正确的是（   ）

A．O2和S2O是氧化剂，Fe2+是还原剂

B．每生成1mol Fe3O4，则转移电子数为2mol

C．参加反应的氧化剂与还原剂的物质的量之比为1:1

D．若有2mol Fe2+被氧化，则被Fe2+还原的O2为0.5mol

答案

答案：D

题目分析：根据反应可知，O2化合价降低，Fe2+、S2O化合价升高，所以氧化剂O2，还原剂Fe2+、S2O。1个Fe3O4生成转移1个电子，1mol Fe3O4转移1mol电子。参加反应的氧化剂的物质的量是1mol，参加反应的还原剂的物质的量是5mol。答案选D。

点评：氧化还原反应中电子的转移是高考的热点，经常跟阿佛加德罗常数一起，应该重视。

多项选择题

下列有关复合风管材料的叙述正确的有( )。

A．铝箔复合发泡保温板材料为阻燃或难燃材料

B．铝箔胶带的氧指数不小于30

C．铝箔复合发泡保温板材为64kg/m3

D．玻璃纤维布复合铝箔的氧指数不小于60

E．铝箔复合保温风管的板材为内外两层，分别由60μm、80μm或200μm的铝箔，中间的发泡聚氨酯黏合而成的
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单项选择题

According to the passage, Crosby has made which of the following assumptions concerning historical means of demography

(A) Migration is in most cases dictated by life course events as opposed to the economic factors that contribute to the development of cities.
(B) Population growth tends not to affect the availability of proxies for replacing emigrants from population centers.
(C) Sedimentary populations are more historically significant than nomadic or migratory ones.
(D) It is permissible to rely upon a single source of information in studying population movement patterns.
(E) Migration can be disregarded as a demographic pattern in historical contexts prior to the development of large cities.
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