Final answer:
After 14,000 years, more than 25mg but less than 50mg of the original 100mg of Carbon-14 would remain, as it is slightly more than two half-lives (11,460 years) but less than three half-lives (17,190 years) of Carbon-14 (5730 years each).
Step-by-step explanation:
If we start with 100mg of Carbon-14, after 14,000 years, we can determine how much Carbon-14 will be left by using the concept of half-life, which is the time it takes for half of a radioactive substance to decay. The half-life of Carbon-14 is 5,730 years. After one half-life, 50mg would remain. After two half-lives (11,460 years), 25mg would remain.
Since 14,000 years is slightly more than two half-lives, we can calculate the remaining amount after 14,000 years by interpolating between the second and third half-life. At the end of the third half-life (17,190 years), 12.5mg would remain. Since 14,000 years is approximately 2.44 half-lives, we would expect slightly more than 25mg but less than 50mg to remain. Exact calculation would require more complex mathematics, such as exponential decay formulas.