If we start with 8000 atoms of radium-226 how much would remain after 3200 years?

2000 atoms

Explanation:

We are given the following;

Initial number of atoms of radium-226 as 8000 atoms

Time taken for the decay 3200 years

We are required to determine the number of atoms that will remain after 3200 years.

We need to know the half life of Radium

Half life is the time taken by a radio active material to decay by half of its initial amount. Half life of Radium-226 is 1600 years Therefore, using the formula;

Remaining amount = Original amount * 0.5^n

where n is the number of half lives

n = 3200 years : 1600 years

= 2

Therefore;

Remaining amount = 8000 atoms * 0.5^2

= 8000 * 0.25

= 2000 atoms

Thus, the number of radium-226 that will remain after 3200 years is 2000 atoms.