Mastering Half-Life Calculations in Radioactive Decay

The video tutorial covers five half-life problems to help students understand the concept of radioactive decay. It begins with an introduction to half-life and the equation used to calculate it. The instructor then solves five problems involving different radioisotopes, calculating either the half-life, remaining mass, or original mass of the samples. Each problem is explained step-by-step, demonstrating how to use the half-life equation and reference tables to find the solution.

What fraction of the original sample remains after three half-lives?

• 1/2

• 1/4

• 1/16

• 1/8

If a sample decays from 80 mg to 5 mg in 32 days, how many half-lives have passed?

• 2

• 3

• 4

• 5

What is the half-life of a radioisotope if it takes 32 days for an 80 mg sample to decay to 5 mg?

• 12 days

• 6 days

• 8 days

• 10 days

How many grams of K42 remain after three half-lives if the initial mass is 16 grams?

• 1 gram

• 2 grams

• 4 grams

• 3 grams

What is the half-life of K42 if 37.2 hours have passed and the half-life is 12.36 hours?

• 5 half-lives

• 3 half-lives

• 2 half-lives

• 4 half-lives

If a 40 gram sample decays to 10 grams in 30 days, how many half-lives have occurred?

• 3

• 2

• 4

• 1

What is the half-life of a radioisotope if 2 half-lives occur in 30 days?

• 10 days

• 12 days

• 15 days

• 18 days

What was the original mass of iodine-131 if 1 gram remains after 5 half-lives?

• 24 grams

• 32 grams

• 8 grams

• 16 grams

How much radon-222 remains after 5 half-lives if the initial mass is 160 mg?

• 5 mg

• 10 mg

• 15 mg

• 20 mg

What is the half-life of radon-222 if 5 half-lives occur in 19.1 days?

• 3.8 days

• 5 days

• 4.2 days

• 4.5 days