[求助]麻烦哪位好心人帮我借下这题呀~~~

yangchen47

The rate of a certain chemical reaction is directly proportional to the square of concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100 percent, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?

A. 100% decrease                                                                                                                                                                                                     

B. 50% decrease

C. 40% decrease

D. 40% increase

E. 50% increase

miaoyu2

答案是什么？

yangchen47

答案D

miaoyu2

我是这么做的 不知道理解的对不对：

设 The rate of a certain chemical reaction 为 R.

      concentration of chemical A为A, 则the square of concentration of chemical A 为A^2

      the concentration of chemical B

则 根据题意 BR/A^2 =t  t为常数。

    变化后，让2BR/[(1+M%)A]^2 还最接近t, 就是想让(1+M%)^2 最接近t, 选项中（1＋40％）^2=1.96 所以是答案。

不知道对不对 牛牛再看看。

miaoyu2

http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1712375&id=181110&skin=0

找到了以前的link

[此贴子已经被作者于2008-9-17 12:24:00编辑过]

miaoyu2

http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=149128

yangchen47

谢谢啦~~~