The graphs shows the amount of a chemical in a water sample at different times after it was first measured. Select all statements that are true. Group of answer choices After 4 hours, there were 100 mg of the chemical in the water. The amount of the chemical in the water sample is decreasing exponentially. The amount of the chemical in the water sample is not decreasing exponentially. When it was first measured, there were 2,000 mg of the chemical in the water sample. It is not possible to tell for certain whether or not the amount of the chemical is decreasing exponentially