Using the half-life graph of cobalt-57, choose ALL the statements that are accurate. es )
A)
The half-life of Co-57 is 20 days.
B)
The half-Life of Co-57 is 10 days.
C)
After fifty days, there is 0% or no Co-57 remaining.
D)
After twenty days have elapsed, about 25% of the Co-57 remains.
E)
Scientists have an 8 gram sample of Co-57. After thirty days, 1 gram
remains.

15. which of the following is not human-caused groundwater pollution? a. water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock. b. water in an aquifer is contaminated by leachate that seeps into the ground from a landfill. c. water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking. d. water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.