Question

The half-life of tritium, or hydrogen-3, is 12.32 years. After about 24.6 years, how much of a sample of tritium will remain unchanged?
a.

1/8
c.

1/3
b.

1/4
d.

1/2

Answer 1

half life equation

An = A0 * (1/2)^(t/h)

where A0 is the initial amount, An is the final amount, t is the total time elapsed, h is the half-life

you can divide both sides by A0 to get

An/A0 = (1/2)^(t/h)

in this case, plug in your total time (24.6 years) and your half life (12.32)

on the left side, you have the fraction An/A0 which is (amount left) / (initial amount) which is equal to the portion of the sample remaining, which will be your solution