Half Life Calculations Practice

Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80 g was obtained. If it takes 10 minutes to set up an experiment using barium-122, how much barium-122 will be left when the experiment begins?

• 0.25g
• 2.5g
• 25g
• 80g

Tags

NGSS.HS-PS1-8

The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?

• 3.0g
• 0.25mg
• 0.3g
• 0.25g

Tags

NGSS.HS-PS1-8

After 4 half-lives,there is now a 1g sample of Krypton-85. What was the original mass of the sample?

• 16g

• 32g

• 0.0625g

• 4g

Tags

NGSS.HS-PS1-8

The half-life of Zinc-71 is 2.4 minutes. If you had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?

• 100.0g

• 50.0g

• 12.5g

• 8.5g

Tags

NGSS.HS-PS1-8

If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?

• 1 half-life
• 2 half-lives
• 3 half-lives
• 4 half-lives

Tags

NGSS.HS-PS1-8

If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.

• 1.25mg
• 1.25g
• 10g
• 10mg

Tags

NGSS.HS-PS1-8

¹⁴₆C has a half-life of 5730 years how many grams of a 4.0 g sample would be left after 3.5 half-lives?

• 1.0 g
• 0.5 g
• 0.38 g
• None would be left

Tags

NGSS.HS-PS1-8

¹⁴₆C has a half life of 5730 years, how many years would it take the 4.0 g sample to decay to 0.25 g?

• 4 years
• 5730 years
• 22,920 years
• 28,650 years

Tags

NGSS.HS-PS1-8

After the third half-life, how much of the sample is left?

• 1/2
• 1/3
• 1/16
• 1/8

Tags

NGSS.HS-PS1-8

Selenium-83 has a half life of 25 minutes. How many minutes would it take for a 20 milligram sample to decay and only have 1.25 milligrams of it remaining? 

• 25 minutes
• 50 minutes
• 75 minutes 
• 100 minutes

Tags

NGSS.HS-PS1-8