Barium - 122 has a half-life of 2 minutes. You just obtained a sample weighing 10.0 grams. It takes 10 minutes to set up the experiment in which barium - 122 will be used. How many grams of barium - 122 will be left when you begin the experiment?

Question

Quizplus · Accepted Answer

Using the formula for radioactive decay, we can calculate the amount of barium - 122 remaining after 10 minutes:

N = N0 * (1/2)^(t/h)

where:
N0 = initial amount of barium - 122 = 10.0 g
N = final amount of barium - 122 (what we're solving for)
t = time elapsed = 10 min
h = half-life = 2 min

Plugging in the values:

N = 10.0 g * (1/2)^(10/2) = 10.0 g * (1/2)^5 = 10.0 g * 0.03125 = 0.313 g

Therefore, the answer is B, 0.313 g of barium - 122 will be left when the experiment begins.

Barium - 122 Has a Half-Life of 2 Minutes