the half-life of plutonium-239 is 24,110 years. How much of an original mass of 100.0 grams remains after 96,440 years?

6.25 g

Explanation:

Concept: Half life

What is half life?

Half life is the time taken by a radioactive substance to decay by half of its original mass.

In this case;

Half life of Plutonium-239 is 24,110 years

Original mass of plutonium-239 is 100 g

Time for the decay is 96,440 years

We are required to calculate the remaining mass;

Using the formula;

Remaining mass = Original mass * 0.5^n

where n is the number of half lives

n = Time : Half life

= 96,440 yrs : 24,110 years

= 4

Therefore;

Remaining mass = 100 g * 0.5^4

= 6.25 g

Thus, the mass of plutonium-239 that will remain after 96,440 years will be 6.25 g