8.50%
12.50%
25%
87.50%
Answer is Wrong!
Answer is Right!
The correct answer is (d).
The half-life of a radioactive substance is the time it takes for half of the atoms in a sample to decay. In this case, the half-life is 60 minutes. This means that after 60 minutes, half of the atoms in the sample will have decayed. After another 60 minutes, half of the remaining atoms will have decayed, and so on.
During 3 hours, there are 6 half-lives. After 1 half-life, 50% of the atoms will have decayed. After 2 half-lives, 75% of the atoms will have decayed. After 3 half-lives, 87.5% of the atoms will have decayed.
Therefore, the fraction of total number of atoms that would have decayed during 3 hours is 87.5%.