Final answer:
To calculate the remaining amount of a radioactive substance after a given time, we use its half-life. In this case, after 10 days, you would expect a 100-gram sample of Cobalt-57 to decay to 50 grams, assuming a 10-day half-life, similar to Ac-225.
Step-by-step explanation:
The task is to determine how much of a 100-gram sample of Cobalt-57 (Co-57) will remain after 10 days. The half-life is a crucial concept here, which indicates the time it takes for half of the radioactive isotopes in a sample to decay. As per the example provided, Actinium-225 (Ac-225) has a half-life of 10 days, meaning if we start with a 100 gram sample, after 10 days, we can expect that half of it would remain, so 50 grams would be left.
Without the specific half-life of Co-57 provided in the question, we can't give a precise answer. However, since the half-life of Ac-225 is also 10 days, we use it as an analogy to explain the concept. A 100-gram sample of a substance with a 10-day half-life would decay to 50 grams after one half-life period (10 days).
Therefore, following one half-life, we can expect a sample to decrease to half its initial mass.