Mastering Half-Life Calculations in Isotopes and Carbon-14

This video tutorial explains how to perform half-life calculations using timelines. It covers two problems: one involving an isotope with a 6-hour half-life and another with Carbon-14's 6,000-year half-life. The instructor demonstrates how to calculate the remaining percentage of an isotope and the time it takes for Carbon-14's activity to fall below a certain level. The video concludes with links to additional resources for more challenging problems.

What is the half-life of an isotope if 100% of it is present at the start?

• 24 hours

• 12 hours

• 3 hours

• 6 hours

What is the first step in solving a half-life problem using the timeline method?

• Estimate the total time

• Draw a timeline with half-lives, time, and percentage

• Calculate the final percentage

• Guess the number of half-lives

What is the purpose of drawing a timeline in half-life calculations?

• To calculate the final amount directly

• To estimate the initial amount

• To visualize the decay process over time

• To guess the number of half-lives

After one half-life, what percentage of the isotope remains?

• 12.5%

• 75%

• 25%

• 50%

How many half-lives are needed for an isotope to reduce to 6.25% of its original amount?

• 4 half-lives

• 5 half-lives

• 2 half-lives

• 3 half-lives

What is the half-life of Carbon-14?

• 6,000 years

• 3,000 years

• 1,000 years

• 12,000 years

What is the initial activity rate of Carbon-14 in the second example?

• 50 counts per minute

• 150 counts per minute

• 100 counts per minute

• 200 counts per minute

How many half-lives does it take for the activity rate to fall below 10 counts per minute?

• 6 half-lives

• 3 half-lives

• 4 half-lives

• 5 half-lives

What is the total time required for the activity rate to fall below 10 counts per minute?

• 30,000 years

• 24,000 years

• 18,000 years

• 36,000 years

What is the activity rate after 3 half-lives?

• 12.5 counts per minute

• 6.25 counts per minute

• 25 counts per minute

• 50 counts per minute