Question

Question #568a2

Answer 1

The amount that remains unchanged is 2.5 g.

Explanation:

The half-life of tritium is 12.32 years.

The formula for calculating the amount remaining after a number of half-lives, `n`, is

`color(blue)(bar(ul(|color(white)(a/a)A = A_0/2^ncolor(white)(a/a)|)))" "`

where `A_0` is the initial amount and `A` is the amount remaining.

`n = 36.93 cancel("y") × "1 half-life"/(12.32 cancel("y")) = "2.998 half-lives"`

`A = A_0/2^n = "20 g"/2^2.998 = "2.5 g"`