How much of a radioactive material with a half life of 12000 years is left after 36000 years of decay?

Answer 1

Since the material will lose one half the initial amount in the first 12,000 yrs. and then one half the remainder each additional 12,000 yrs, the amount remaining after 36,000 years will be 1/8'th the original amount.

1/2 remains after 12,000, then 1/2 of the half, or 1/4 remains after the second 12,000, and 1/2 the quarter, or 1/8'th after the third 12,000 years.

Answer 2

There is insufficient information in the question to provide a specific answer it.

The equation for radioactive decay is AT = A0 2(-T/H).

For the above equation, AT is the final amount, A0 is the initial amount, T is time elapsed (120 years), and H is the half-life. As you can see, there are three unknown variables. You must have two of them to be able to solve for the third. In this case, if the elapsed time is 120 years, you cannot know how much would be left unless you know the number of years in the half-life.

Answer 3

Let's see. 1g = 1,000 mg

2g = 2,000 mg

half life of tritium is 12 years.

How much will we have after 120 years?

We now have 2,000 mg

After 12 years 1,000 mg

After 24 years 500 mg

After 36 years 250 mg

After 48 years 125 mg

After 60 years 62.5 mg

After 72 years 31.25 mg

After 84 years 15.625 mg

After 96 years 7.8125 mg

After 108 years 3.90625 mg

After 120 years 1.953125 mg

Of course the above includes too many significant figures.

If we start out wit 2 g, we are probably measuring to 2 place accuracy.

The final result would probably look something like this.

We now have 2,000 mg

After 12 years 1,000 mg

After 24 years 500 mg

After 36 years 250 mg

After 48 years 130 mg

After 60 years 63 mg

After 72 years 31 mg

After 84 years 16 mg

After 96 years 7.8 mg

After 108 years 3.9 mg

After 120 years 2. mg