问题 选择题

20℃时,氯化钠的溶解度是36g,这表示(  )

A.20℃时,100g氯化钠饱和溶液中含氯化钠36g

B.20℃时,100g水中溶解36g氯化钠,溶液达到饱和状态

C.100g水中最多溶解36g氯化钠

D.20℃时,氯化钠在水中溶解36g,溶液达到饱和状态

答案

根据溶解度的定义,固体物质的溶解度有四个条件,一定温度,100g溶剂;饱和状态,单位是克,缺一不可.

A、100g氯化钠饱和溶液中含氯化钠36g,说法错误,应为20℃时,100g水溶解氯化钠36g,故A错误;

B、20℃时,100g水中溶解36g氯化钠,溶液达到饱和状态.说法正确,故B正确;

C、没有说明温度,故C错误;

D、没有水的质量,故D错误.

故选B.

阅读理解

阅读理解。

     Mr and Mrs Wilson lived in a big city, and one summer they went to the country for their vacation. They enjoyed

it very much , because it was a quiet , clean place.

     One day they went for a walk early in the morning and saw an old man.   He was sitting alone in the warm sun in

front of his house. Mr Wilson asked him , " Do you like living in a quiet place?"

     The old man said, "Yes,l do. "

     Mr Wilson said,"What are the good things about it?"

     The old man answered, " Well, everybody knows everybody. People often come and see me, and I often go and

see them. And there are lots of children here. "

     Mr Wilson said, "That's interesting. And what are the bad things?"

     The old man thought for a few minutes and said, " Well, the same things , really. "

1. Where did Mr and Mrs Wilson live? 

A. In a city.              

B. In a country.

C. In town.                

D. In Beijing.

2. Why did they like the country?

A. Because it was far.

B. Because they had a farm in the country.

C. Because it was quiet and clean.

D. Because it was near.

3. Was the old man their uncle?

A. Yes , he was.                

B. We don't know.

C. I think so.          

D. Certainly.

4. What did the old man think were the good things about the country?

A. Everybody knew each other.

B. Everybody didn't know each other.

C. It was clean and quiet.

D. It was nice.

5. Did the old man think the good things and the bad things in the country were the same?

A.No,he didn't.    

B.Yes,he did.

C.I don't know.    

D.I don't think so

判断题