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问题 选择题

设NA代表阿伏加德罗常数，下列说法不正确的是（  ）。

A．14 g氮气所含原子数为NA

B．1 mol 水中所含电子数为10NA

C．32 g O2与32 g O3所含原子数分别为2NA和3NA

D．0.5 molNa2CO3与1.5 molH2O所含氧原子数目均为1.5NA

答案

答案：C

一个水分子是由两个氢原子和一个氧原子构成的，而一个氢原子含1个电子，一个氧原子含8个电子，所以一个水分子含10个电子，即1 mol水中所含电子数为10 mol，即10NA，所以B正确。

阅读理解

阅读短文，然后根据短文内容完成句子。

     Look at the picture on the blackboard. We can see a house in it. Behind the house there is a hill with

 many trees. Near the hill we can see a river. There are three boats in the river. One is blue, the other two

  are yellow. There are some Young Pioneers in those boats. Near the house we can see a big tree.

 Under the tree there is a small bus. It's a white bus. 

  

1. There is a _____ on the _____ .

2. _____ is the hill? It's _____ the house.

3. There are a lot of _____ on the hill.

4. Some _____ _____ are in the boats.

5. Is there a _____ _____ bus under the big tree? Yes, there is.

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单项选择题

某班50名学生右眼视力的检查结果如下表所示：

视力 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.2 1.5
人数 1 1 3 4 3 4 4 6 8 10 6
则全班学生右眼视力的众数是______。

A．0.1

B．1.2

C．1.0

D．0.4
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