Question

Potassium-40 has a half-life of approximately 1.25 billion years. Approximately how many years will pass before a sample of potassium-40 contains one-eighth the original amount of parent isotope?

Answer 1

3.75 billion years

Step-by-step explanation:

From the question given above, the following data were obtained:

Half-life (t½) = 1.25 billion years

Number of half-lives (n) = 3

Time (t) =?

The time taken for the sample of potassium-40 to contains one-eighth the original amount of parent isotope can be obtained as:

n = t / t½

3 = t / 1.25

Cross multiply

t = 3 × 1.25

t = 3.75 billion years.

Therefore, it will take 3.75 billion years for the sample of potassium-40 to contains one-eighth the original amount of parent isotope