Radioactive Decay and Half-Lives

The video tutorial explains the concept of half-life through examples of radium, tritium, and thallium decay. It covers calculations of remaining substance amounts over time, expressed in grams, percentages, and fractions. The tutorial also demonstrates how to determine the half-life of a substance using decay data and introduces more complex half-life problems involving exponents and logarithms.

If you start with a 120 gram sample of radium, how much will be left after 44 days?

• 7.5 grams

• 60 grams

• 15 grams

• 30 grams

How many half-lives does it take for radium to decay from 120 grams to 7.5 grams?

• 5 half-lives

• 3 half-lives

• 2 half-lives

• 4 half-lives

What percentage of radium is left after 44 days?

• 50%

• 25%

• 12.5%

• 6.25%

What fraction of radium is left after 44 days?

• 1/4

• 1/16

• 1/8

• 1/32

How long does it take for an 80 gram sample of tritium to decay to 2.5 grams?

• 61.5 years

• 49.2 years

• 36.9 years

• 24.6 years

How many half-lives are required for tritium to decay from 80 grams to 2.5 grams?

• 6 half-lives

• 4 half-lives

• 3 half-lives

• 5 half-lives

What percentage of tritium is left after 5 half-lives?

• 25%

• 3.125%

• 6.25%

• 12.5%

What fraction of tritium is left after 5 half-lives?

• 1/64

• 1/32

• 1/16

• 1/8

How long is the half-life of thallium if it decays from 200 grams to 12.5 grams in 20 minutes?

• 2.5 minutes

• 5 minutes

• 10 minutes

• 20 minutes

How many half-lives does it take for thallium to decay from 200 grams to 12.5 grams?

• 2 half-lives

• 3 half-lives

• 4 half-lives

• 5 half-lives