HALF-LIFE AND DECAY SERIES

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

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

Tags

NGSS.HS-PS1-8

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

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

What percent of carbon-14 would be left after 5730 years?

• 100%
• 75%
• 50%
• 25%

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 type of decay is shown here

²³⁸₉₂U ---> ²³⁴₉₀Th + ⁴₂He.

• alpha

• beta

• gamma

Tags

NGSS.HS-PS1-8

Identify the type of nuclear decay shown here

²¹⁴₈₃Bi → ⁰_-1e + ²¹⁴₈₄Po

• alpha

• beta

• gamma

Tags

NGSS.HS-PS1-8

After 32,000 years how much Plutonium-239 is left undecayed?

• 32%

• 40%

• 5%

Answer explanation

After 32,000 years, 40% of Plutonium-239 is left undecayed, which corresponds to the correct answer choice.

Tags

NGSS.HS-PS1-8

Which radioactive isotope decays quicker?

• Carbon-14

• Plutonium-239

• they have the same decays

Answer explanation

Carbon-14 decays quicker than Plutonium-239. This is because Carbon-14 has a shorter half-life compared to Plutonium-239.

Tags

NGSS.HS-PS1-8