Half-Life and Decay Problems

The video tutorial explains the concept of half-life through various examples involving isotopes like cesium-137, actinium-226, sodium-25, isotope X, selenium-83, and polonium-218. It covers calculations to determine the remaining quantity of a substance after a certain period, based on its half-life. The tutorial also includes practical applications, such as determining the initial amount needed to achieve a desired quantity after decay.

If cesium-137 has a half-life of 30 years, how much of a 1 gram sample remains after 90 years?

• 0.0625 grams

• 0.125 grams

• 0.25 grams

• 0.5 grams

How many half-lives does actinium-226 go through in 58 hours if its half-life is 29 hours?

• 1

• 4

• 2

• 3

What is the remaining mass of actinium-226 after 58 hours if you start with 100 mg?

• 6.25 mg

• 12.5 mg

• 25 mg

• 50 mg

If sodium-25 has a half-life of 60 seconds, how many half-lives occur in 3 minutes?

• 1

• 2

• 3

• 4

How much sodium-25 remains after 3 minutes if you start with 5 mg?

• 0.625 mg

• 1.25 mg

• 2.5 mg

• 0.3125 mg

How many years does it take for 4 mg of isotope X to decay to 0.5 mg if its half-life is 2 years?

• 6 years

• 4 years

• 8 years

• 2 years

How long does it take for 10 mg of selenium-83 to decay to 1.25 mg if its half-life is 25 minutes?

• 25 minutes

• 75 minutes

• 50 minutes

• 100 minutes

If polonium-218 has a half-life of 3 minutes, how much remains after 15 minutes from a 2 g sample?

• 0.25 g

• 0.5 g

• 1 g

• 0.0625 g

How many half-lives does polonium-218 go through in 15 minutes?

• 5

• 6

• 3

• 4

To have 0.1 g of polonium-218 after 30 minutes, how much should you initially order?

• 51.2 g

• 25.6 g

• 102.4 g

• 12.8 g