University:
High School
Course:
High School Physics
Academic year:

2022
Views:

402

Pages:

2
Author:

Cloe Pope

Radioactivity and Half-Lives Review Worksheet 1. What is а half-life? 2. lf we start with 400 atoms of а radioactive substance, how many would remain after one halflife? .й, After 2 half-lives? -- After 3 half-lives? -- After 4 half-lives? -- 3. lf we start with 16 grams of а substance, how much will remain after 3 half-lives? 4. А sample of carbon-14 has been decaying for 22,920 years and is now 35.0 grams. What was the size of the original sample? (The half-life of carbon-14 is 5,730 years) 7. How old is а skeleton sample if the current amount of carbon in the bones is 3.125%? (Assume you started with 100%) 8. lf you started with 120 grams of а radioactive substance, and now you have 15 grams, how many half lives have passed? 9. The half-life of isotope Х is 2.0 years. How many years would it take for а 4.0 mg sample of isotope Х to decay and have only 0.50 mg of it remain? 10. The half-life of Ро-218 is three minutes. How much of а 200 atom sample will remain after 15 minutes? 11. The half-life of Au-198 is 2.69 days. How long does it take а 180g sample to decay to 1/8 its original mass? •.. 1г. What is the half-lite ot а radioactive sample if 100.0 grams of it decays to 12.5 grams in 24.3 hours? 1 h(Jv. (' 13. How long will it take а sample of 131 1 to decay to 12.5% assuming its half-life is 8.07 days? 14. Sodium-25 was to Ье used in an experiment, but it took 3.0 minutes to get the sodium from the reactor to the laboratory. lf 5.0 mg of sodium-25 was removed from the reactor, how many mg of sodium-25 were placed in the reaction v�ssel 3.0 minutes later if.the h�lf-I,ife of sodium-25 is 60 seconds? 15. Actinium-226 have а h�lf.:ljf� �f 29' QQlJrs: .lf 10.0 g of actinium-226 disintegrates over а period of 145 hours, how many mg of actinium-226 will remain 7 **Уои need to do dimensioпal ana!ysis to so/ve this опе! **