Half Life Calculations Practice

The diagram shows 32 atoms

32 of the Red are the parent isotope

0 of the atoms are daughter isotopes

How many half-lives have occurred?

• 0

• 1

• 2

• 3

Tags

NGSS.HS-PS1-8

Imagine you have 50,000 atoms of uranium-238. If U-238 has a half-life of 4.5 billion years, how many U-238 atoms will be left after 4.5 billion years?

• 25,000

• 50,000

• 12,500

• 0

Tags

NGSS.HS-PS1-8

Why do some elements have half-lives?

• they radioactively decay

• half of their atom gets stolen

• They are Twizzlers that break in half

Tags

NGSS.HS-PS1-8

The mass of a parent isotope is 100 g. How many grams of the parent isotope will remain after 2 half-lives?

• 25

• 50

• 12.5

• 0

Tags

NGSS.HS-PS1-8

How long would it take for an element with a half-life of 100 years to reach 5 half-lives?

• 50

• 500

• 5000

• 5

Tags

NGSS.HS-PS1-8

After 22,800 years, approximately what percentage of the original carbon-14 remains?

• 15%

• 12.5%

• 6.25%

• 3.125%

Which diagram best represents the percentage of this radioactive isotope sample that will remain after 2 half-lives?

• 
• 
• 
• 

Tags

NGSS.HS-PS1-8

The Half Life of Californium 252 is 5 years.

• TRUE

• FALSE

Tags

NGSS.HS-PS1-8

If one-fourth of the carbon-14 is remaining then how many half-lives have passed?

• 1

• 2

• 3

• 4

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