Question

If 16 radioactive parent atoms decayed to half of their original number after one year, how many radioactive parent atoms would be left after two years?

1. 4
2. 2
3. 1
4. 0
5. 8

Answer 1

After two half-life periods, starting with 16 radioactive parent atoms, 4 atoms would remain, as each half-life period reduces the number of undecayed atoms by half.

Step-by-step explanation:

When dealing with the concept of radioactive decay, it's important to understand the principle of a half-life, which is the time it takes for half of the radioactive parent atoms in a sample to decay into daughter elements. If you start with 16 radioactive atoms and they decay to half their number in one year, you would be left with 8 atoms after the first year. Upon the completion of the second year, which consists of another half-life period, half of those remaining would decay, leaving you with 4 radioactive parent atoms.

Answer 2

After two years, and thus two half-lives, 4 radioactive parent atoms would remain from the initial 16, as each half-life results in the number of radioactive nuclei being halved.

Step-by-step explanation:

If 16 radioactive parent atoms decayed to half their number after one year, 8 would remain after the first year. According to the concept of half-life, the number of radioactive nuclei decreases exponentially. After two years, another half-life would pass, and half of the remaining 8 atoms would decay, leaving us with 4 radioactive parent atoms. This process of radioactive decay shows that the radioactive atoms are replaced by their decay products, also known as daughter elements.