Practice Radioactivity in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

The spontaneous emission of radiation (alpha particles, beta particles, or gamma rays) from an unstable atomic nucleus as it transforms into a more stable configuration.

Some nuclei are unstable and shed particles to reach a more stable state โ€” like a unstable pile of blocks rearranging.

Showing a random 20 of 50 problems.

Example 1

easy
Order alpha, beta, and gamma by increasing penetrating power.

Example 2

medium
Complete the beta decay: 614Cโ†’ย ??N+ฮฒโˆ’^{14}_{6}C \rightarrow\ ^{?}_{?}N + \beta^-. Give N's mass and atomic number.

Example 3

medium
Identify the unknown XX: 84210Poโ†’X+ฮฑ^{210}_{84}Po \rightarrow X + \alpha.

Example 4

hard
After two consecutive alpha decays of 92238U^{238}_{92}U, what nucleus remains?

Example 5

easy
Can temperature or pressure change a radioactive isotope's decay rate?

Example 6

medium
A radioisotope has a half-life of 8 days. What fraction remains after 24 days?

Example 7

easy
How many protons are in an alpha particle?

Example 8

challenge
A sample's activity drops from 800 to 50 counts/min. How many half-lives elapsed, and if each is 3 min, what is the total time?

Example 9

hard
A patient is given a tracer with activity 8000 counts/min. The activity drops to 500 counts/min after 24 hours. Find the half-life.

Example 10

medium
Worked example: a sample drops from 1000 atoms to 125 atoms. How many half-lives have passed?

Example 11

easy
What particle is emitted in alpha decay?

Example 12

medium
A sample contains 4.0ร—10204.0 \times 10^{20} atoms with a half-life of 1 year. How many atoms remain after 4 years?

Example 13

easy
Does gamma radiation change the atomic number of a nucleus?

Example 14

easy
Fill in: In alpha decay, the mass number of the parent nucleus decreases by ____.

Example 15

challenge
In the U-238 to Pb-206 chain, after the 8 alpha decays, how many beta-minus decays are needed to reach Z = 82?

Example 16

medium
Fill in: An isotope's half-life is the time for ____ of its nuclei to decay.

Example 17

easy
Which type of radiation can be stopped by a sheet of paper?

Example 18

medium
A 64 g sample of iodine-131 (half-life 8 days) sits for 24 days. How much remains?

Example 19

medium
Worked example: classify each as alpha, beta-minus, or gamma. (a) emission of a 24He^{4}_{2}He nucleus, (b) emission of a high-energy photon, (c) a neutron becoming a proton + electron.

Example 20

challenge
Uranium-238 decays through a chain emitting a total alpha and beta particles to become lead-206. How many alpha decays occur?
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