The amount of uranium-235 contained within a sample is given by the exponential equation: equation where A represents the remaining amount of uranium-235, Ao represents the initial amount of uranium-235. What does the equation represent?
1) The rate of decay of uranium-235
2) The half-life of uranium-235
3) The amount of uranium-235 remaining after a certain time
4) The amount of uranium-235 decayed after a certain time