Half Life Practice

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

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 half life of iodine-131 is 8.040 days. What percentage of an iodine-131 sample will remain after 40.20 days?

• 312.5%
• 31.25%
• .3125%
• 3.125%

Tags

NGSS.HS-PS1-8

What is the half-life of iodine-131?

• 32 days
• 8 days
• 16 days
• 24 days

Tags

NGSS.HS-PS1-8

What is the Half life of this isotope?

• 5 seconds

• 10 seconds

• 15 seconds

• 20 seconds

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

NGSS.HS-PS1-8

What is the mass of an original 5.60 grams sample of iron-53 that remains unchanged after 25.53 minutes?

• 0.35 grams

• 0.70 grams

• 1.40 grams

• 2.80 grams

Tags

NGSS.HS-PS1-8

A radioactive isotope has a half life of 2.5 years. What fraction of the original mass remains unchanged after 10 years?

• 1/2

• 1/4

• 1/8

• 1/16

Tags

NGSS.HS-PS1-8

After decaying 48 hours, 1/16 of the original mass of a radioisotope sample remains unchanged. What is the half life of this radioisotope?

• 3 hour

• 9.6 hour

• 12 hour

• 24 hour

Tags

NGSS.HS-PS1-8

What is the total number of years that must pass before only 25 grams of an original 100 gram sample of C-14 remains unchanged?

• 2865 years

• 5730 years

• 11,460 years

• 17,190 years

Tags

NGSS.HS-PS1-8