Final answer:
After two half-lives, a 500-gram radioactive sample will be reduced to 125 grams, as each half-life results in the decay of half of the remaining material.
Step-by-step explanation:
The question pertains to the concept of radioactive decay and half-life, which is a key idea in nuclear physics and chemistry. The half-life of a radioactive isotope is the time it takes for half of the radioactive atoms in a sample to decay into their daughter elements. In this example, a 500-gram sample of a radioactive material will be examined over two half-lives. After the first half-life, half of the 500 grams will have decayed, leaving 250 grams. After the second half-life, half of the remaining material will decay, leaving 125 grams of the original material.