问题 问答题

2003 年春天,传染性非典型肺炎( SARS )在我国部分地区流行.“万众一心,众志成城,抗击非典”,是当前和今后一段时间内摆在全国人民面前的一项重大而艰巨的任务.进行合理的药物消毒是预防非典感染的重要手段之一.过氧乙酸是较为有效的一种消毒剂,其化学式为 CH3COOOH,根据过氧乙酸的化学式进行计算.

(1)过氧乙酸中碳、氢、氧三种元素的质量比(最简比).

(2)38g过氧乙酸中含碳元素的质量是多少g?

(3)152g 过氧乙酸与多少克硫酸( H2SO4)所含氧元素质量相等?

答案

(1)过氧乙酸中,碳、氢、氧元素的质量比为(12×2):4:(16×3)=6:1:12;

(2)38g过氧乙酸中含碳元素的质量为38g×

12×2
76
×100%=12g;

(3)152g 过氧乙酸所含氧元素质为152g×

16×3
76
×100%=96g;

由于过氧乙酸与硫酸中所含氧元素的质量相等,因此硫酸中所含氧元素的质量也是96g;

故含96g氧元素的硫酸的质量为96g÷(

16×4
98
×100%)=147g.

故答案为:(1)6:1:2; (2)12g;(3)147g.

阅读理解

根据短文内容,回答下列问题。

     John was a farmer. He liked to grow flowers in his garden when he was free. One Sunday morning

after breakfast he put on his old clothes and began digging in his garden at eight. He dug and dug. Half an

hour later he suddenly found a coin near his foot. He was very glad, "He put it in his right pocket. A few

minutes later, he found another one. He picked it up and put it in to the same pocket. The same thing

happened for the third,  the fourth and the fifth time."He was very glad and told his wife about it. She was

very glad, too. She said, "A thief took away a lot of coins from a shop a few days ago. The police caught

him but they didn't find any coins." Then John went on digging some more coins, but just when he began

to dig, he felt something cold in his trousers. It ran down one of his legs. He put his hand down quickly

and the coin came into his hand. Now he knew there was a hole in his pocket.

1. What was in John's garden?

                                                                  

2. When did John find a coin in his garden?

                                                                  

3. What did John tell his wife?

                                                                  

4. Where was a hole?

                                                                  

5. How many coins did John dig out in his garden?

                                                                  

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