Half Life Problems

You have 100 grams of radioactive C-14. How many grams are left after 2 half-lives? 

• 100 grams

• 25 grams

• 2 grams

• 50 grams

Tags

NGSS.HS-PS1-8

How much strontium-90 will remain after 4 half-lives, if the initial amount is 4.0 g?

• 3.0g

• 0.25mg

• 0.3g

• 0.25g

Tags

NGSS.HS-PS1-8

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

If we start with 64 g of radium-226, how much remains after 1 half-life?

• 16g

• 32g

• 128 g

• 4g

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

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

What is the count rate after 45 days for a radioactive isotope with a half-life of 15 days and an initial count rate of 200 counts per second?

• 50 counts per second

• 100 counts per second

• 12.5 counts per second

• 25 counts per second

Tags

NGSS.HS-PS1-8

What is the count rate after 60 days for a radioactive isotope with a half-life of 20 days and an initial count rate of 1000 counts per second?

• 500 counts per second

• 250 counts per second

• 125 counts per second

• 62.5 counts per second

How can half-life be applied to solve problems related to radioactive isotopes?

• By analyzing the count rate

• By calculating the decrease in count rate

• By determining the decay rate

• By calculating the number of nuclei

Tags

NGSS.HS-PS1-8

How can you determine the half-life of an isotope from a graph?

• By counting the number of decays per second

• By measuring the time it takes for the number of nuclei to halve

• By measuring the time it takes for the number of nuclei to double

• By measuring the time it takes for the count rate to fall to half its initial level

Tags

NGSS.HS-PS1-8