NAME ______________________________________________________ DATE _________________ Half-life Practice 1. What is half-life? _THE AMOUNT OF TIME REQUIRED FOR HALF OF THE ORIGINAL SAMPLE TO DECAY_ 2. If we start with 400 atoms of a radioactive substance, how many would we have after: a. one half-life? _200__ c. three half-lives? _50_ b. two half-lives? __100_ d. four half-lives? _25_ 3. If we start with 48 atoms of a radioactive substance, how many would remain after: a. one half-life? _24_ c. after three half-lives? __6_ b. two half-lives? _12_ d. after four half-lives? _3_ Using the graph to the right, answer the following questions. 4.What is the half-life of each element? A.1.25 x 109 years B. 4.5 x 109 years C. 13 x 109 years 5.Which element has the shortest half-life? A Use the graph to answer the following questions. 6. How many atoms are in the original sample size of this radioisotope? 80 7. How long is the half-life? 2 DAYS This study source was downloaded by 100000855867892 from CourseHero.com on 11-07-2022 08:44:28 GMT -06:00 https://www.coursehero.com/file/82084099/Chem-Half-life-Practice-1-docx/ Use the table on the right to answer the following questions. 8. How long is a half-life for carbon-14? 5730 YEARS 9. If only 25% of the carbon-14 remains, how old is the material containing the carbon-14? 10,740 The table below shows the radioactive decay of a 600 g sample of Iodine-125. % of Parent Isotope Fraction of Parent Time HalfMass (g) of Parent Remaining Isotope Remaining Isotope (days) Lives 0 0 100% 1/1 600 60 1 50% 1/2 300 120 2 25% 1/4 150 180 3 12.5% 1/8 75 240 4 6.25% 1/16 37.5 300 5 3.125% 1/32 18.75 360 6 1.56% 1/64 9.4 10. What percent of iodine is left if 5 half-lives have passed? 0 300 450 325 562.5 581.25 590.6 ____3.25 %___ 11. What is the half-life time of Iodine-125? __ 60 DAYS _ 12. What fraction of the Iodine-125 remains after 300 days have passed? __ 1/32 _ 13. How many half-lives have occurred for there to be 75 grams remaining? __ 3 __ This study source was downloaded by 100000855867892 from CourseHero.com on 11-07-2022 08:44:28 GMT -06:00 https://www.coursehero.com/file/82084099/Chem-Half-life-Practice-1-docx/ Powered by TCPDF (www.tcpdf.org) Mass (g) of Daughter Isotope