Water gatherers. The solar system didn't wrap up its formation process after the planets formed. Earth stands out from the planets because of its high water content, which many scientists suspect contributed to the evolution of life.
Density = mass /volume of the body. mass = 10.88 g, volume of the liquid displaced= 49.4-43.5=5.9 ml.
density = 10.88/5.9=1.844 g/ml~1.84 g/ml
The volume displaced is exactly the same as that of the body (The Eureka fro Archimedes!)
(1) 36 days is 8 half-life periods,
so 24mg becomes 24mg times (1/2)^8 = 24 mg/256 = 0.094 mg
(2) 9.6/1.2 = 8, which means three half-life periods went by.
At the end of 4.5 days, there were 4.8 mg
At the end of 9.0 days, there were 2.4 mg
At the end of 13.5 days, there were 1.2 mg
(3) The activity is proportional to the amount of radioactive material remaining,
so after two half-life periods, the activity should be 1/4 of what it originally was.
So the initial activity was probably 12.0 Ci
