题干

以下是某研究小组探究影响化学反应快慢的一些因素的相关数据(常温通常指20℃;“浓度”指溶质的质量分数)

 实验序号

 过氧化氢溶液浓度/%

 过氧化氢溶液质量/g

 温度/℃

 二氧化锰用量/g

 氧气体积/ml

 反应所需时间/s

5

12

20

0.2

125

11

30

12

20

0.2

125

2

30

12

40

/

125

148

30

12

90

/

125

82

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同类题4

阅读下面短文,从短文后各题所给的四个选项()A、B、C和D)中,选出可以填入空白处的最佳选项。

    I sat down at my desk and tried to focus on my studies. In just seven more days, finals would be over and all the students in my college 1 would be leaving to   go home-2 me. I would be moving 3 to another dormitory for the Christmas break.

    I had no 4. I was a student from Pennsylvania attending college in Utah and my family of ten couldn't 5 to pay for my ticket home. The only 6 I was even able to attend college was that I had received several scholarships.

    I started at the white snow dancing through the air. This would be my 7 Christmas away from home. I felt so 8 that I could weep. 9 I swallowed down the ache that was rising in my throat, my phone rang suddenly. I reached over and picked it 10.

    “Hello?”

    “Hi, Teddi. This is Elsie.” What was my boss from high school grocery job 11 me for? “All the workers here 12 that you weren't able to make it home this year.13 we bought you a ticket. You're coming home!”

    I screamed.

    Fifteen minutes later I was off the14and jumping up and down for 15. Neighbors came over to see what the 16 was all about.

    “I'm going home for Christmas! My17 at my high school job bought me a ticket!” I told them.

    Christmas 18, I was awoken by laughs and screams of joy. The smell of roasting turkey and the wrapping paper(包装纸)that grew higher and higher filled me with love and 19. The kindness of some special fiends 20 me to have the best Christmas ever.