1. The rate of a certain chemical reaction is directly proportional to the square of the 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%, 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%increase b. 100%decrease c. 40%increase d.40%decrease e.50%increase 答案是c. 不懂呢... 2. A certain library assesses fines for overdue books as follow on the first day that a book is overdue, the total fine is $0.10, for each additional day that the book is overdue, the total fine is either increased by $0.30 or doubled, whichever results in the lesser amount, what is the total fine for a book on a fourth day it is due? a. $1.00 b. $0.90 c.0.70 d. 0.80 e. 1.50 答案是c. 算的是$0.80 |