Please hurry!! Iron-59 has a half-life of 44.5 days. How much of a 3.00 mg sample will be left after 222.5 days?

A: 0.03mg
B: 0.09mg
C: 0.90mg
D: 6.00mg

Which of the following natural processes is most likely to support the formation of an underwater sinkhole? a pollution buildup from deposited minerals b limestone cave collapsing due to changes in sea level c erosion of large amounts of sand moved by ocean waves d oxidation of rock formed by chemical weathering