【单选题】In a given 1st order reaction A ---> products, the initial concentration of A is 0.40 M. What will be the concentration of A after 15 seconds if the half-life of the reaction is 3 seconds?
【简答题】Questions 51 to 55 are based on the following passage. You may have heard some of the fashion industry horror stories: models eating tissues or cotton balls to hold off hunger, and models collapsing f...