Question

Iridium‑192 is one radioisotope used in brachytherapy, in which a radioactive source is placed inside a patient's body to treat cancer. Brachytherapy allows the use of a higher than normal dose to be placed near the tumor while lowering the risk of damage to healthy tissue. Iridium‑192 is often used in the head or breast. Use the radioactive decay curve of iridium‑192 to answer the three questions. The percentage of the sample remaining is plotted on the y axis versus the time in days on the x axis. Some of the points included on the decay curve are 0 days 100 percent remaining, 5 days 95.41 percent remaining, 25 days 79.08 percent remaining, 35 days 71.99 percent remaining, 40 days 68.69 percent remaining, 45 days 65.54 percent remaining, 55 days 59.67 percent remaining, 65 days 54.32 precent remaining, 70 days 51.83 percent remaining, 75 days 49.45 percent remaining, 80 days 47.19 percent remaining, 85 days 45.02 percent remaining, 105 days 37.31 percent remaining, 115 days 33.97 percent remaining, 120 days 32.41 percent remaining, 130 days 29.51 percent remaining, 145 days 25.63 percent remaining, and 150 days 24.46 percent remaining. If the initial sample is 8.00 g, what mass of the original iridium‑192 remains after 85 days? mass remaining: g Estimate the half‑life of the radioisotope. half-life: days How many days would it take for three‑fourths of the sample to decay? time:

Answer 1