Example: The half-life of carbon-14 is 5,730 years. If you started with 100.0 g of carbon-14, how much would remain after 4 half-lives? Please explain how you got the answer.

#1-6

mendez (mmm5697) – Half Life – cartas – (12621302) 1

This print-out should have 6 questions.

Multiple-choice questions may continue on

the next column or page – find all choices

before answering.

001 10.0 points

What does NOT describe a nuclear reaction?

1. Reaction rate is not influenced by external

factors.

2. All of these correctly describe a nuclear

reaction.

3. Relatively small amounts of energy are

released or absorbed.

4. Elements may be converted from one to

another.

5. Particles in the nucleus are involved.

002 10.0 points

The half-life of 137Ce is 30 years. How many

grams of 137Ce must be produced now to have

a sample containing 32 g of 137Ce 140 years

from now?

Answer in units of g

003 10.0 points

The half-life of 222Rn is 3.82 days. If we have

62 g of 222Rn how many grams will be left

after 10 half-lives?

Answer in units of grams

004 10.0 points

The half life of thallium-201 is 21.5 hours. We

have 88 g of thallium-201 how many grams

will be left after 10 half-lives?

Answer in units of grams

005 10.0 points

The half-life of carbon-14 is 5,730 years. If

you started with 100.0 g of carbon-14, how

much would remain after 4 half-lives?

1. 12.5 g

2. 6.25 g

3. 25.0 g

4. 57.3 g

006 10.0 points

239Pu has a half-life of 24000 years. If we have

10 g of 239Pu, how many grams will be left

after 38000 years?

Answer in units of g