Question

An element has a half-life of 2.5 days. If it begins with 100 atoms, how many will be left after 5 days?

Answer 1

There’s 25 atoms left

Answer 2

25

Step-by-step explanation:

Half life equation is:

A = A₀ (½)^(t / T)

where A is the final amount, A₀ is the initial amount, t is time, and T is the half life.

Given that A₀ = 100, t = 5, and T = 2.5:

A = 100 (½)^(5 / 2.5)

A = 100 (½)^2

A = 100 (¼)

A = 25

There will be 25 atoms left.