Half-Life

Fermium-253 has a half-life of 0.334 seconds. A radioactive sample is considered to be completely decayed after 10 half-lives. How much time will elapse for this sample to be considered gone?

• 0.334 seconds

• 3.34 seconds

• 1.77 seconds

• 13.4 seconds

Tags

NGSS.HS-PS1-8

Geologist use the time it takes for a radioactive isotope to decay to half its original mass called a___________.

• radioactive decay

• isotope

• half-life

• carbon dating

Tags

NGSS.HS-PS1-8

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 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

The diagram shows 32 atoms.

16 of the Red are parent isotopes

16 of the Green 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

You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years. 
How many grams are left after 1 half life? 

• 100 grams

• 25 grams

• 2 grams

• 50 grams

Tags

NGSS.HS-PS1-8

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

• 
• 
• 
• 

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

A 50.0 g sample of a radioactive element has a half-life of 40 years. How much mass will be left after 80 years?

• 50

• 25

• 12.5

• 6.25

Tags

NGSS.HS-PS1-8