Ascientist is measuring the amount of radioactive material in an unknown substance. when he begins measuring, there are 56.8 grams of radioactive substance. twelve days later, there are 55.45 grams. after 25 days, there are 54.03 grams. after 41 days, there are 52.32 grams. assuming that the decay is exponential, find the equation that determines the number of grams remaining after x days and use the equation to determine the amount of radioactive material remaining after 500 days.2.21 g12.65 g2.25 g20.88 g

Universal law of radioactive decay states that:

Where No is an initial number of atoms, N is a number of atoms after time t and lambda is the decay constant. We can use mas of an atom instead of a number of atoms because we know that every atom has the same mass.

In order to calculate how many atoms are left after 500 days, we need to find decay constant.
We can do this by using the information given in the problem. We know that after 12 days we are left with 55.45 grams and we know the initial amount. With this information we can calculate decay constant:

Now we simply plug in t=500 and calculate the

The final answer is D (20.88g).