Half Life

The rate at which a radioactive element decays is its ____.

• quarter life
• whole life
• wonderful life 
• half life

Tags

NGSS.HS-PS1-8

what's the half life of this substance?

• 1 day
• 2 days
• 3 days
• 4 days

Tags

NGSS.HS-PS1-8

The half-life of Zn-71 is 2.4 minutes. If one 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

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

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

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

What is a half-life?

• The average time it takes for any element to disappear completely 
• The time it takes for a radioactive atom to lose half its neutrons
• The time it takes for half of any number of radioactive atoms to decay
• The time it takes for a radioactive atom to lose half its electrons 

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

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

CCSS.HSF.LE.A.4

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