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NA代表阿伏加德罗常数，下列叙述错误的是

A．10mL质量分数为98%的H2SO4，用水稀释至100mL，H2SO4的质量分数小于9.8%

B．在H2O2+Cl22HCl+O2反应中，每生成32g氧气，则转移2NA个电子

C．标准状况下，分子数为NA的CO、C2H4混合气体体积约为22.4L，质量为28g

D．NA个一氧化碳分子和0.5mol甲烷的质量比为7:2

答案

答案：A

A、硫酸溶液浓度越大，密度越大

设原溶液的密度为，溶质的质量为m，则：，推出；

设原溶液的密度为，则其质量分数为：==9.8%×＞9.8%

B、在H2O2+Cl22HCl+O2反应中，两个—1价氧升为0价，两个0价氯降至—1价，故有两个电子的转移。由方程式可看出，每生成32g氧气，则转移2NA个电子转移

C、CO、C2H4的摩尔质量相同，所以标准状况下，分子数为NA的CO、C2H4混合气体体积约为22.4L（阿伏加德罗定律适用于纯净或混合气体），质量为28g

D、NA个一氧化碳分子和0.5mol甲烷的质量比为28：8即7:2

故答案为A

阅读理解
阅读理解。
      It was a Monday morning. As the teacher walked into the classroom, he heard a low voice (低声),
"Here's the teacher. I'm sure this boring fellow (家伙) is going to talk about how to use commas (逗号)."
It was a boy's voice and the teacher knew who he was.
     However, the teacher didn't get angry. He said nothing about it, but really began to talk about how to
use commas And then he wrote the following sentence on the blackboard, "Nick says the teacher is a
boring fellow."
     The class laughed and Nick's face turned red.
     "Now," said the teacher, "I'll tell you the importance of commas." He put two commas in the sentence,
and then read, "Nick, says the teacher, is a boring fellow." 
     The whole class laughed again. Nick felt very surprised first, then his face much redder. Finally he
couldn't help (情不自禁) laughing with the other students, too.
1. What subject did the teacher teach the students?
[ ]
A. Math
B. English
C. Music
2. What kind of boy was Nick like?
[ ]
A. A tall boy
B. A healthy boy
C. A funny boy
3. I think Nick liked to have ______ lessons.
[ ]
A. boring
B. interesting
C. no
4. "Nick says the teacher is a boring fellow." is ______ "Nick says the teacher, is a boring fellow."
     in the meaning.
[ ]
A. the same as
B. kind of different from
C. quite different from
5. What do you think of the teacher? He is very ______.
[ ]
A. boring
B. good
C. bad
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选择题

你认为治疗煤气中毒最好采取下列哪种方法（　　）

A．森林浴

B．手术治疗

C．有氧呼吸

D．高压氧治疗
查看答案