Half Life Calculations

What is the half-life of iodine-131?

• 32 days

• 8 days

• 16 days

• 24 days

Tags

NGSS.HS-PS1-8

The % of the parent isotope remaining after 1 Half Life.

• 50%

• 25%

• 12.5%

• 6.25%

Tags

NGSS.HS-PS1-8

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

If 20 g of copper-64 has a half-life of 13 hours, what mass of copper-64 will remain after 26 hours?

• 20 g

• 10 g

• 5 g

• 2.5 g

Tags

NGSS.HS-PS1-8

How many seconds does it take a 100.0g sample of Arsenic-81, with a half-life of 33.0 seconds, to decay to 6.250g?

Mathematical Equivalence

ON

How much of an 80 g sample will remain after 21.2 years?

• 40 g

• 20 g

• 10 g

• 5 g

Tags

NGSS.HS-PS1-8

An isotope of cesium 138 has a half-life of 30 years. If 1.00 g of cesium-138 disintegrates over a period of 90 years, how many grams of cesium-138 would remain?

Mathematical Equivalence

ON

Tags

NGSS.HS-PS1-8

A radioactive isotope has a half-life of 2.5 years. Match the correct fraction of the original mass that remains unchanged after the given amount of years

• 1/8 radioactive

• 10 years

• 1/4 radioactive

• 7.5 years

• 1/16 radioactive

• 5 years

• 1/32 radioactive

• 2.5 years

• 1/2 radioactive

• 12.5 years

When an isotope goes through 2 half-lives, _____ _________________ remains

• 1/4 or 25%

• 1/2 or 50%

• 1/8 or 12.5%

Tags

NGSS.HS-PS1-8