The percentage of the original nuclei of the sample of a radioactive substance left after 5 half - lives is

Answer Details

The percentage of the original nuclei of a sample of a radioactive substance left after 5 half-lives can be calculated using the radioactive decay formula. For each half-life that passes, the amount of radioactive substance remaining is halved. After five half-lives, the amount of radioactive substance remaining is 1/2 x 1/2 x 1/2 x 1/2 x 1/2 = 1/32 of the original amount.
To convert this to a percentage, we multiply by 100, giving 3.125%, which is closest to 3%. Therefore, the correct option is (c) 3%.