Radiation #2 (Half-life & Contamination)

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

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

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

What is the half-life of iodine-131?

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

What is the Half life of this isotope?

• 5 seconds

• 10 seconds

• 15 seconds

• 20 seconds

What is the Half Life of this isotope?

• 3 days

• 5 days

• 8 days

• 10 days

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

When nuclei decay, massive amounts of __________ is released.

• energy
• jello
• protons
• neutrons

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