The half-life of carbon-14 is about 5700 years. If you left those 100 carbon-14 atoms to sit around for 5700 years, how many would you expect to decay during that time?

50 atoms have decayed during that time

Explanation:

The radioactive decay is represented as

Where N is the amount of radioactive element after a certain time period

N0 is the amount of radioactive element during the initial time period

X is the half life of the radioactive element

Substituting the given  values in above equation,  we get:

atoms

So, 50 atoms of carbon-14 remain are left after decaying for 5700 years.

Hence,  atoms of carbon-14 that decay during 5700 years are 100-50 - 50