Question

The radioisotope Cobalt-60, which is used in cancer therapy, has a half-life of 5.27 years. What percentage of the original radioactive parent is left after one year?

A) 90.2%
B) 80.8%
C) 75.0%
D) 85.1%

Answer 1

The percentage of the original radioactive parent that is left after one year is 90.2%.

Step-by-step explanation:

The percentage of the original radioactive parent that is left after one year can be determined by understanding the concept of half-life. For cobalt-60, which has a half-life of 5.27 years, 50% remains after one half-life, 25% remains after two half-lives, and so on. Since one year is less than the half-life of cobalt-60, it is less than one half-life, and therefore more than 50% of the original radioactive parent will be left. The correct answer is A) 90.2%.