What fraction of a radioactive sample remains after one half-life?

Answer 1

Half of the original sample of a radio isotope remains after a half-life period. After two half-life periods, one-fourth of the radio isotope remains.

Answer 2

after 3 half lives you basically multiply a half by a half by a half. eg, .5 to the power of 3, gives 1/8. 1/2 first time, 1/4 second time, 1/8 third time

Answer 3

By definition, half the sample remains after one half-life.

Half of one half, or one quarter, remains after two half-lives, etc.

Answer 4

One quarter of the original. After one "half-life", half of the radioactive atoms will have broken up; after another half-life, half of the remainder will decay.

Answer 5

1/2 remains after 1 half life. So 1/2 x 1/2 = 1/4 remains after 2 half-lives.

Answer 6

Half of the former number of atoms