Half Life Review

What is half-life?

• The amount of time it takes for some of the nuclei in a sample of the isotope to decay

• The amount of time it takes for half the electrons in a sample of the isotope to decay

• The amount of time it takes for half the nuclei in a sample of the isotope to decay

• the amount of time it takes to double the nuclei in a sample of the isotope to decay

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

CCSS.HSF.LE.A.4

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

If the half life of a radioactive element is 100yrs, how long would it take for the radioactivity to reduce by one half?

• 200yrs
• 100yrs
• 50yrs
• 300yrs

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

The % of the parent isotope remaining after 2 half lives.

• 50%

• 25%

• 12.5%

• 6.25%

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

CCSS.HSF.LE.A.4

The diagram shows 32 atoms. The red spheres are the parent isotopes. 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

What percentage of rubidium-87 atoms will be left after four half lives?

• 25.0%

• 12.5%

• 6.25%

• 3.125%

Tags

NGSS.HS-PS1-8