After three half lifes, the fraction of a radioactive material that has decayed is
Answer Details
The fraction of a radioactive material that has decayed after three half-lives is represented by the second option:
1
3
Explanation: The half-life of a radioactive material is the amount of time it takes for half of the radioactive atoms to decay. After one half-life, half of the original radioactive material has decayed. After two half-lives, only one-fourth (1/2 x 1/2) of the original radioactive material remains. After three half-lives, only one-eighth (1/2 x 1/2 x 1/2) of the original radioactive material remains, meaning that seven-eighths (1 - 1/8 = 7/8) of the material has decayed. Therefore, the fraction of radioactive material that has decayed after three half-lives is 7/8.