问题 选择题

设NA表示阿伏加德罗常数的值,下列说法正确的是

A.常温常压下,5.6L CH4含C—H键数目为NA

B.常温常压下,100g17%H2O2水溶液含氧原子总数为NA

C.标准状况下,5.6L O2与适量Na加热反应,转移电子数一定为NA

D.常温常压下,14g乙烯与丙烯的混合气体,含碳原子总数为NA

答案

答案:D

题目分析:A、条件不正确,常温常压下气体的摩尔体积不是22.4mol/L,错误;B、溶剂水中含有氧原子,错误;C、O2与适量Na加热反应生成Na2O2,标准状况下,5.6L O2与Na加热反应,转移电子数为0.5NA,错误;D、正确。

阅读理解
Reading comprehension.
      Everybody talks about the weather; it's the most common subject of conversation, for example, "Isn't
it a nice day?" "Do you think it will rain?" "I think it is going to snow," All this are the common ways of
starting a conversation.
      Many people think they can tell what the weather is going to be like. But they hardly ever agree with
each other. One man may say, "Do you see how cloudy it is in the east? It is going to rain tomorrow."
Another man will say, "Yes, it's cloudy in the east.We are going to have a fine day tomorrow."
      People often look for the weather they want. When a farmer needs water,he looks for something to
tell him it is going to rain; he won't believe anything else. When friends have a picnic, they are so sure the
weather is going to clear up very quickly that they won't sit eating their lunch while it rains.
     Almost everyone listens to what the weatherman says. But he does not always tell us what we want,
and once in a while he makes a mistake.Still, he probably comes closer to being correct than anyone else.
1. When we start a conversation with our friends, we usually ____.
[ ]
A: ask their names
B: talk about the weather
C: say hello to them
D: ask their address
2. "Isn't it a nice day?" The sentence means ____.
[ ]
A: he doesn't know if it is a fine day
B: he doesn't think it is a fine day
C: he thinks it is a fine day
D: he asks others' opinion
3. When we talk about the weather, we usually say ____.
[ ]
A: "Are you cold?"
B: "Are you well?"
C: "What day is today?"
D: "What a fine day."
4. When people want to have a pionic, they will ____.
[ ]
A: enjoy their pionic in the rain
B: look for something to tell them it is going to be fine
C: wait until it is fine
D: believe what the weatherman says
5. The weatherman ____.
[ ]
A: tells us the weather we hope for
B: never makes a mistake
C: comes closer to being correct than anyone else
D: should be blamed
6. The word "conversation" means        .
[ ]
A: 讲演
B: 报告
C: 谈话
D: 作文
选择题