Half Life Calculations Practice

An Isotope of Cesium-137 has a half life of 30 years. If 1.0 g of Cesium-137 disintegrates over a period of 90 years, how many grams of Cesium-137 would remain? 

• .125 grams

• .5 grams

• 15 grams

• 45 grams

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

Actinium-226 has a half life of 29 hours. If 100 milligrams of Actinium disintegrate over a period of 58 hours, how many milligrams of Actinium will remain? 

• 100 mg

• 50 mg

• 25 mg

• 58 mg

Tags

NGSS.HS-PS1-8

What is the half life of Polonium-218 if 0.0625 grams remains of a 2.00 gram original sample after 15 minutes?

• 5 minutes

• 3 minutes

• 15 minutes

• 7.5 min

Tags

NGSS.HS-PS1-8

What percent of carbon-14 would be left after 11,460 years?

• 100%

• 75%

• 50%

• 25%

Tags

NGSS.HS-PS1-8

When an isotope goes through 4 half-lives, _____ _________________ remains

• 1/4 or 25%

• 1/8 or 12.5%

• 1/16 or 6.25%

Tags

NGSS.HS-PS1-8

How many grams will remain after 100 g of cobalt-60 has gone through 3 half-lives?

• 50 g

• 25 g

• 12.5 g

• 6.25 g

Tags

NGSS.HS-PS1-8

Approximately how many grams of a 50-g sample of radium-226 will remain unchanged after 6400 years? The half-life for Radium - 226 is 1600 years according to Table N

You must use the chart to see if your answer is correct

• 25g

• 6.25g

• 128g

• 3.13g

If 20 g of copper-64 has a half-life of 13 hours, what mass of copper-64 will remain after 39 hours? ( Drag the answer to the space.)​ ​ (a)  

• 2.5 g

• 20 g

• 10 g

• 1.25 g

• 5 g

• 0.625

Tags

NGSS.HS-PS1-8

When an isotope goes through 2 half-lives, _____ _________________ remains

• 1/4 or 25%

• 1/2 or 50%

• 1/8 or 12.5%